Method for preparation of glazed donuts using rapid freezing and multi-stage thawing thereof

Abstract

The present invention relates to a method for manufacturing glazed donuts using rapid freezing and multi-stage thawing. Based on 100 parts by weight of a mixed powder containing flour, yeast, purified water, whipping cream, corn syrup, tangzhong, and butter are mixed in stages to prepare a dough with a final dough temperature of 25 to 28 degrees. The dough is divided and shaped into portions of 2,000 to 2,085 grams, sealed in a sanitary bag, and aged at a low temperature of 2 to 3 degrees for 20 to 24 hours to stabilize the gluten structure and form a deep fermented flavor. After recovering the low-temperature aged dough to room temperature, it is rolled out to a thickness of 3 to 10 millimeters and cut into rings. The dough is then fermented for 1 to 2 hours at a temperature of 25 to 30 degrees and a humidity of 70 to 80 percent. Finally, the fermented dough is heated in edible oil at 170 to 180 degrees for a total of 3 to 4 minutes The present invention provides an integrated method for manufacturing glazed donuts that can realize quality standardization, labor cost reduction, operational simplification, productivity improvement, and inventory management efficiency by achieving all of the following: maximizing flavor through low-temperature aging, preserving quality through rapid freezing, ensuring operational flexibility through multi-stage thawing, and increasing production efficiency through the separation of post-processing steps; by manufacturing a fried donut with an internal temperature of 95 to 98 degrees, cooling the fried donut at room temperature for 5 to 10 minutes, then rapidly freezing it at a freezing temperature of -35 to -40 degrees for 25 to 40 minutes to minimize the size of ice crystals, optionally applying a multi-stage thawing method in which the rapidly frozen fried donut is thawed at room temperature of 22 to 26 degrees for 12 hours or more, or thawing it in a convection oven at 180 degrees for 3 minutes; and performing a post-processing step of injecting cream into the thawed fried donut and coating it with glaze.

Description

Technology Field

[0001] The following examples relate to a method for manufacturing glazed donuts using rapid freezing and multi-stage thawing. Background Technology

[0002] Doughnuts are a representative bakery product made by shaping flour dough into a ring and frying it in cooking oil, and they are a convenience food widely consumed around the world. In particular, glazed doughnuts are products made by injecting cream into a fried doughnut and coating the surface with sugar, and they are highly preferred by consumers due to their soft texture and sweet taste.

[0003] The traditional donut manufacturing process is based on the principle of producing and selling on the same day. Since this method requires completing all processes—from preparing and fermenting the dough to frying, filling with cream, and glazing—within a single day, skilled personnel are essential, and it has limitations in that product quality may vary from store to store. Furthermore, operational efficiency is low due to long manufacturing times and complex processes, and there are issues with the difficulty of responding quickly to sudden fluctuations in demand.

[0004] Recently, low-temperature fermentation technology has been introduced in the bakery industry to improve the flavor and texture of dough. Low-temperature fermentation is a technique that involves fermenting dough at refrigerated temperatures for an extended period to slow down yeast activity, stabilize the gluten structure, and create a deep fermented flavor. However, conventional low-temperature fermentation technology has been primarily applied to the production of fresh bread, and integrated processes linked to its application to fried products—including freezing, thawing, and post-processing—have rarely been attempted.

[0005] Meanwhile, frozen bakery technology has been utilized to increase production efficiency and extend shelf life; however, conventional freezing methods suffer from issues such as damage to product texture due to ice crystal growth and quality degradation resulting from moisture loss after thawing. Particularly for fried products, the application of freezing technology has been limited because the crispy outer layer becomes tough and the interior dries out significantly during the freezing and thawing process.

[0006] In the existing glazed donut manufacturing process, cream had to be injected and glaze applied immediately after frying, so all processes had to proceed continuously, which significantly limited the flexibility of production planning. In addition, since production had to be based on the daily sales volume for each store, there was a recurring problem where waste losses occurred if sales were lower than expected, and sales opportunities were lost due to inventory shortages if sales were higher than expected.

[0007] Therefore, there is a need to develop an integrated manufacturing process that utilizes low-temperature fermentation technology to produce donut dough with excellent flavor and texture, applies rapid freezing technology after frying to enable long-term storage while minimizing quality degradation, and allows for cream injection and glazing operations by thawing in various ways as needed. If such technology is developed, it is expected to enhance the competitiveness of the bakery industry by achieving quality standardization, maximizing production efficiency, and ensuring flexibility in inventory management. Prior art literature

[0008] Korean Registered Patent 10-300547 Korean Published Patent 10-2012-0060551 Korean Registered Patent 10-1979993 Korean Published Patent 10-2010-0113998 The problem to be solved

[0009] The present invention was devised to solve the problems of the prior art described above, and its main purpose is to provide a manufacturing method capable of efficiently mass-producing high-quality glazed donuts by combining low-temperature aging technology and rapid freezing technology.

[0010] The specific objective of the present invention is, first, to provide a method for producing a dough in which gluten is sufficiently formed and the dough temperature is controlled within an appropriate range by mixing a mix powder containing flour, yeast, purified water, whipping cream, corn syrup, tangzhong, and butter in stages.

[0011] Second, the present invention provides a low-temperature aging method in which the dough is divided into portions of a certain weight, shaped, sealed, and aged at a low temperature for a long time at a refrigerator temperature to stabilize the gluten structure and form a deep fermented flavor, thereby maintaining a moist and chewy texture for a long time even after frying.

[0012] Third, the present invention provides a method for preparing a donut dough having a uniform porous structure by restoring the cold-aged dough to an appropriate temperature, rolling it out to a uniform thickness, cutting it into a ring shape, and shaping it, and then performing a second fermentation in an environment where temperature and humidity are controlled.

[0013] Fourth, the invention provides a frying method in which fermented dough is fried uniformly on both sides in edible oil at an appropriate temperature to ensure it is fully cooked to the inside and crispy on the surface, and then cooled appropriately after frying to a state suitable for rapid freezing.

[0014] Fifth, the invention provides a rapid freezing method that minimizes the size of ice crystals and prevents tissue damage by rapidly freezing fried donuts at a low temperature of minus 35 to minus 40 degrees for a short period of time, thereby allowing the quality to be maintained similar to that immediately after frying even after thawing.

[0015] Sixth, by providing a multi-stage thawing method that allows quick-frozen fried donuts to be naturally thawed at room temperature for a long time or thawed in a short time using a convection oven as needed, it enables flexible response to operational conditions.

[0016] Seventh, by performing the post-processing steps of injecting cream and coating glaze into the thawed fried donuts after the rapid freezing and thawing processes, the production process and the final product completion point are separated, thereby improving productivity and maximizing the efficiency of inventory management.

[0017] Ultimately, the present invention aims to significantly improve the competitiveness of the bakery industry by providing an integrated method for manufacturing glazed donuts that can achieve all of the following: improvement of flavor and texture through low-temperature aging, preservation of quality and extension of shelf life through rapid freezing, securing operational flexibility through multi-stage thawing, and increased productivity through the separation of post-processing steps. means of solving the problem

[0018] The present invention relates to a method for manufacturing a glazed donut using rapid freezing and multi-stage thawing, comprising: a) a dough preparation step of preparing a dough having a final dough temperature of 25°C to 28°C by stepwise mixing 100 parts by weight of a mixed powder containing flour, 1.0 to 1.5 parts by weight of yeast, 30 to 40 parts by weight of purified water, 8 to 12 parts by weight of whipping cream, 1.5 to 3 parts by weight of corn syrup, 8 to 13 parts by weight of tangzhong, and 8 to 12 parts by weight of butter; b) a low-temperature aging step of dividing the dough into portions weighing 2000g to 2085g, shaping them, sealing them in a sanitary bag, and aging them at a low temperature for 20 to 24 hours at a refrigeration temperature of 2°C to 3°C; c) a forming and fermentation step in which the above-mentioned low-temperature aged dough is left at room temperature, rolled out to a thickness of 3 mm to 10 mm, cut into a ring shape to form, and fermented for 1 to 2 hours at a temperature of 25°C to 30°C and a humidity of 70% to 80%; d) a frying step in which the above-mentioned fermented dough is fried on both sides in edible oil at 170°C to 180°C for a total of 3 to 4 minutes to produce a fried donut with an internal temperature of 95°C to 98°C; e) a rapid freezing step in which the above-mentioned fried donut is cooled at room temperature for 5 to 10 minutes, and then rapidly frozen at a freezing temperature of -35°C to -40°C for 25 to 40 minutes; f) a thawing step of thawing the above-mentioned rapid-frozen fried donut at room temperature of 22°C to 26°C for 12 hours or more, or thawing in a convection oven at 180°C for 3 minutes; and g) a post-processing step of injecting cream into the thawed fried donut and coating it with glaze; the present invention provides a method for manufacturing a glazed donut using rapid freezing and multi-stage thawing, characterized by comprising: a thawing step of thawing the above-mentioned rapid-frozen fried donut at room temperature of 22°C to 26°C for 12 hours or more, or thawing it in a convection oven at 180°C for 3 minutes; and a post-processing step of injecting cream into the above-mentioned thawed fried donut and coating it with glaze.

[0019] At this time, the dough preparation step comprises: a1) a first mixing step in which the mix powder and the yeast are added to a mixer and mixed at low speed for 1 minute to uniformly disperse the ingredients; a2) a second mixing step in which the purified water, the whipping cream, and the corn syrup are added to the ingredients mixed in the first step and mixed at low speed for 2 to 3 minutes to hydrate the dough; a3) a third mixing step in which the tangzhong is added to the hydrated dough and mixed at medium speed for 2 minutes to improve the viscoelasticity of the dough; a4) a fourth mixing step in which the butter is added to the dough and mixed at medium speed for 8 minutes to absorb the butter while forming gluten; and a5) a dough temperature checking step in which the temperature of the dough after mixing is completed is measured and confirmed to be within the range of 25°C to 28°C.

[0020] At this time, the low-temperature aging step comprises: b1) a dough dividing step in which the dough obtained from the dough preparation step is divided into portions weighing 2000g to 2085g; b2) a dough forming step in which the divided dough is rolled by hand to form a spherical shape with a smooth surface; b3) a sealing step in which the formed dough is individually sealed in a sanitary bag; and b4) a cold aging step in which the sealed dough is low-temperature aged at a refrigeration temperature of 2°C to 3°C for 20 to 24 hours to stabilize the gluten structure and form a fermented flavor.

[0021] At this time, the molding and fermentation steps are characterized by comprising: c1) a dough temperature recovery step in which the dough that has undergone the low-temperature aging step is removed from a refrigerator and left at room temperature for 10 to 30 minutes; c2) a dough spreading step in which the dough is rolled out to a thickness of 3 mm to 10 mm using a roller; c3) a donut molding step in which the rolled-out dough is cut into a ring shape using a donut cutter and molded; c4) a secondary fermentation step in which the molded donut dough is secondarily fermented for 1 to 2 hours in a fermentation chamber where a temperature of 25°C to 30°C and a humidity of 70% to 80% are maintained; and c5) a fermentation completion step in which fermentation is completed when the thickness of the donut dough increases to 1.5 to 2 times the initial thickness.

[0022] At this time, the frying step comprises: d1) an oil preheating step of preheating edible oil to a temperature of 170°C to 180°C; d2) a first side frying step of frying the fermented dough in the preheated edible oil for 1 minute 30 seconds to 2 minutes; d3) a second side frying step of flipping the dough over and frying the second side for 1 minute 30 seconds to 2 minutes; and d4) an oil removal and cooling step of removing the fried donut from the edible oil, placing it on a wire, and cooling it at room temperature for 5 minutes to 10 minutes while removing excess oil from the surface; and is characterized in that the internal temperature of the fried donut reaches 95°C to 98°C. Effects of the invention

[0023] The method for manufacturing a glazed donut using rapid freezing and multi-stage thawing according to the present invention provides the following significant effects.

[0024] First, the present invention applies a low-temperature aging technique to age the dough at a refrigerated temperature of 2 to 3 degrees for 20 to 24 hours, thereby allowing yeast activity to proceed slowly, which results in the stable formation of a gluten structure and the generation of a deep fermented flavor. Donuts produced through this low-temperature aging process maintain a moist and chewy texture for a long time even after frying, and are characterized by a nutty and subtle fermented aroma, demonstrating superior quality in terms of flavor and texture compared to donuts produced by a general aging method.

[0025] Second, the present invention has the effect of preventing tissue damage by minimizing the size of ice crystals formed inside and outside the cells through rapid freezing of fried donuts at a very low temperature of -35 to -40 degrees for 25 to 40 minutes. In the case of conventional slow freezing methods, large ice crystals are formed, destroying cell membranes and causing a large amount of moisture to leak out upon thawing, resulting in a significant deterioration in quality. In contrast, the rapid freezing method of the present invention forms fine ice crystals uniformly, allowing the texture and moisture content to be maintained similar to that immediately after frying even after thawing.

[0026] Third, the present invention provides a multi-stage thawing method for thawing rapidly frozen fried donuts at room temperature for more than 12 hours or in a convection oven at 180 degrees for 3 minutes, thereby providing the effect of securing flexibility to select the optimal thawing method according to operational conditions and time availability. Thawing at room temperature allows for the natural recovery of quality when sufficient time is available, while thawing in a convection oven allows for a rapid response when products need to be prepared urgently, thus enabling effective adaptation to various business environments.

[0027] Fourth, the present invention has the effect of establishing an efficient production system by separating the cream injection and glaze coating processes into post-processing steps following rapid freezing and thawing, thereby mass-producing semi-finished products with frying completed at a central production facility and storing them frozen, and allowing each store to thaw them and perform only post-processing when needed. Through this, complex processes requiring skilled personnel are intensively performed centrally, while stores perform only simple tasks, thereby reducing labor costs and simplifying operations.

[0028] Fifth, the present invention has an excellent effect in achieving quality standardization. Since mass production is carried out at a central production facility under precisely controlled process conditions, quality variations that may occur between stores or workers are minimized, and products of consistent quality can be stably supplied. This contributes significantly to enhancing brand image and improving customer satisfaction.

[0029] Sixth, the present invention has the effect of dramatically improving productivity. Since fried donuts can be flash-frozen and stored for up to a week, they can be produced in advance during periods of low demand and stored as inventory, and supplied quickly during periods of high demand, thereby maximizing the efficiency of production planning. In addition, since mass production is possible without the constraints of daily production volume, economies of scale can be realized.

[0030] Seventh, the present invention has the effect of providing flexibility in inventory and demand response. Having flash-frozen semi-finished products allows for a rapid response to sudden increases in orders or special events, and even if sales volume is lower than expected, waste losses can be minimized by storing them in a frozen state. This significantly reduces the risk of inventory management and contributes to increasing business stability.

[0031] Eighth, the present invention has the effect of improving distribution and logistics efficiency. Since semi-finished products in a frozen state can be transported stably, it facilitates business expansion to distant stores or new regions, and a nationwide supply chain can be effectively established by utilizing a frozen distribution network.

[0032] Ninth, by combining low-temperature aging and rapid freezing processes, this invention achieves the effect of realizing simultaneous improvements in quality and efficiency that could not be achieved with the existing same-day production and same-day sales method. This integrated approach, which maximizes flavor through low-temperature aging, preserves quality through rapid freezing, and increases productivity through separate post-processing, presents a new paradigm for the bakery industry.

[0033] Tenth, the present invention also has positive effects from an environmental perspective. By minimizing waste losses and enabling the establishment of energy-efficient production plans, it contributes to reducing food waste and building a sustainable production system.

[0034] As described above, the present invention has an excellent effect of dramatically improving the competitiveness of the bakery industry by providing an innovative glazed donut manufacturing method that achieves excellent quality, production efficiency, and operational flexibility by uniquely combining low-temperature aging technology and rapid freezing technology and introducing a multi-stage thawing method. Specific details for implementing the invention

[0035] Hereinafter, embodiments are described in detail with reference to the attached drawings. However, various modifications may be made to the embodiments, and thus the scope of the patent application is not limited or restricted by these embodiments. It should be understood that all modifications, equivalents, and substitutions to the embodiments are included within the scope of the rights.

[0036] Specific structural or functional descriptions of the embodiments are disclosed for illustrative purposes only and may be modified and implemented in various forms. Accordingly, the embodiments are not limited to the specific disclosed forms, and the scope of this specification includes modifications, equivalents, or substitutions that fall within the technical concept.

[0037] Terms such as "first" or "second" may be used to describe various components, but these terms should be interpreted solely for the purpose of distinguishing one component from another. For example, the first component may be named the second component, and similarly, the second component may be named the first component.

[0038] When it is stated that a component is "connected" to another component, it should be understood that it may be directly connected to or coupled with that other component, or that there may be other components in between.

[0039] The terms used in the embodiments are for illustrative purposes only and should not be interpreted as intended to be limiting. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0040] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the embodiments pertain. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0041] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0042] In the embodiments of the present invention, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in the embodiments of the present invention.

[0043] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are exemplary, and therefore the present invention is not limited to the depicted details. Furthermore, in describing the present invention, if it is determined that a detailed description of related known technology may unnecessarily obscure the essence of the present invention, such detailed description is omitted. Where terms such as "includes," "has," or "is made up" are used in this specification, other parts may be added unless "only" is used. Where a component is expressed in the singular, it includes cases where it includes the plural unless specifically stated otherwise.

[0044] In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement.

[0045] The size and thickness of each component shown in the drawings are illustrated for convenience of explanation, and the present invention is not necessarily limited to the size and thickness of the illustrated components.

[0046] The features of each of the various embodiments of the present invention may be combined or combined with one another, either partially or wholly, and as will be fully understood by those skilled in the art, various technical interlocking and operation are possible, and each embodiment may be implemented independently of one another or together in an interlocking relationship.

[0047] The present invention relates to a method for manufacturing a glazed donut using rapid freezing and multi-stage thawing, comprising: a) a dough preparation step of preparing a dough having a final dough temperature of 25°C to 28°C by stepwise mixing 100 parts by weight of a mixed powder containing flour, 1.0 to 1.5 parts by weight of yeast, 30 to 40 parts by weight of purified water, 8 to 12 parts by weight of whipping cream, 1.5 to 3 parts by weight of corn syrup, 8 to 13 parts by weight of tangzhong, and 8 to 12 parts by weight of butter; b) a low-temperature aging step of dividing the dough into portions weighing 2000g to 2085g, shaping them, sealing them in a sanitary bag, and aging them at a low temperature for 20 to 24 hours at a refrigeration temperature of 2°C to 3°C; c) a forming and fermentation step in which the above-mentioned low-temperature aged dough is left at room temperature, rolled out to a thickness of 3 mm to 10 mm, cut into a ring shape to form, and fermented for 1 to 2 hours at a temperature of 25°C to 30°C and a humidity of 70% to 80%; d) a frying step in which the above-mentioned fermented dough is fried on both sides in edible oil at 170°C to 180°C for a total of 3 to 4 minutes to produce a fried donut with an internal temperature of 95°C to 98°C; e) a rapid freezing step in which the above-mentioned fried donut is cooled at room temperature for 5 to 10 minutes, and then rapidly frozen at a freezing temperature of -35°C to -40°C for 25 to 40 minutes; f) a thawing step of thawing the above-mentioned rapid-frozen fried donut at room temperature of 22°C to 26°C for 12 hours or more, or thawing in a convection oven at 180°C for 3 minutes; and g) a post-processing step of injecting cream into the thawed fried donut and coating it with glaze; the present invention provides a method for manufacturing a glazed donut using rapid freezing and multi-stage thawing, characterized by comprising: a thawing step of thawing the above-mentioned rapid-frozen fried donut at room temperature of 22°C to 26°C for 12 hours or more, or thawing it in a convection oven at 180°C for 3 minutes; and a post-processing step of injecting cream into the above-mentioned thawed fried donut and coating it with glaze.

[0048] At this time, the dough preparation step comprises: a1) a first mixing step in which the mix powder and the yeast are added to a mixer and mixed at low speed for 1 minute to uniformly disperse the ingredients; a2) a second mixing step in which the purified water, the whipping cream, and the corn syrup are added to the ingredients mixed in the first step and mixed at low speed for 2 to 3 minutes to hydrate the dough; a3) a third mixing step in which the tangzhong is added to the hydrated dough and mixed at medium speed for 2 minutes to improve the viscoelasticity of the dough; a4) a fourth mixing step in which the butter is added to the dough and mixed at medium speed for 8 minutes to absorb the butter while forming gluten; and a5) a dough temperature checking step in which the temperature of the dough after mixing is completed is measured and confirmed to be within the range of 25°C to 28°C.

[0049] At this time, the low-temperature aging step comprises: b1) a dough dividing step in which the dough obtained from the dough preparation step is divided into portions weighing 2000g to 2085g; b2) a dough forming step in which the divided dough is rolled by hand to form a spherical shape with a smooth surface; b3) a sealing step in which the formed dough is individually sealed in a sanitary bag; and b4) a cold aging step in which the sealed dough is low-temperature aged at a refrigeration temperature of 2°C to 3°C for 20 to 24 hours to stabilize the gluten structure and form a fermented flavor.

[0050] At this time, the molding and fermentation steps are characterized by comprising: c1) a dough temperature recovery step in which the dough that has undergone the low-temperature aging step is removed from a refrigerator and left at room temperature for 10 to 30 minutes; c2) a dough spreading step in which the dough is rolled out to a thickness of 3 mm to 10 mm using a roller; c3) a donut molding step in which the rolled-out dough is cut into a ring shape using a donut cutter and molded; c4) a secondary fermentation step in which the molded donut dough is secondarily fermented for 1 to 2 hours in a fermentation chamber where a temperature of 25°C to 30°C and a humidity of 70% to 80% are maintained; and c5) a fermentation completion step in which fermentation is completed when the thickness of the donut dough increases to 1.5 to 2 times the initial thickness.

[0051] At this time, the frying step comprises: d1) an oil preheating step of preheating edible oil to a temperature of 170°C to 180°C; d2) a first side frying step of frying the fermented dough in the preheated edible oil for 1 minute 30 seconds to 2 minutes; d3) a second side frying step of flipping the dough over and frying the second side for 1 minute 30 seconds to 2 minutes; and d4) an oil removal and cooling step of removing the fried donut from the edible oil, placing it on a wire, and cooling it at room temperature for 5 minutes to 10 minutes while removing excess oil from the surface; and is characterized in that the internal temperature of the fried donut reaches 95°C to 98°C.

[0052] Reasons for selecting each material and technical significance

[0053] Each ingredient used in the manufacturing method of the present invention was carefully selected to optimize the quality of the donut and the efficiency of the manufacturing process, and the content range of each ingredient was determined by considering its effect on the physicochemical properties of the dough and the sensory quality of the final product.

[0054] The mixed powder containing flour serves as the main ingredient of the present invention and acts as the framework forming the structure of the donut. The gluten protein contained in the flour combines with water during the dough mixing process to form a viscoelastic gluten network; this gluten network is essential for capturing carbon dioxide produced by yeast during the fermentation process to expand the dough and maintain the shape of the donut after frying. The mixed powder was selected to have flour as the main component while pre-mixing various additives necessary for bread making, thereby simplifying the manufacturing process and ensuring uniformity of quality. In the present invention, the mixed powder is set to 100 parts by weight, and the ratios of all other ingredients are systematically defined based on this standard, thereby ensuring precision and reproducibility of the formulation.

[0055] Yeast is a microorganism responsible for the fermentation of dough; it plays a role in expanding the dough and forming a fermented flavor by metabolizing sugars to produce carbon dioxide and alcohol. In the present invention, yeast was selected to be used in a range of 1.0 to 1.5 parts by weight per 100 parts by weight of mixed powder, which is the optimal content for preventing over-fermentation while maintaining an appropriate fermentation rate under low-temperature aging conditions. If the yeast content is less than 1.0 part by weight, fermentation is insufficient during the low-temperature aging period, resulting in improper expansion of the dough and weak formation of the fermented flavor. If it exceeds 1.5 parts by weight, the fermentation rate becomes excessively fast even under low-temperature conditions, causing over-fermentation during the aging period of 20 to 24 hours, which may lead to the dough becoming rancid or its structure weakening. Therefore, the present invention simultaneously achieves stable fermentation and excellent flavor by selecting a yeast content optimized for the specific conditions of low-temperature aging.

[0056] Purified water is an essential component for the hydration of dough, playing a role in enabling the proteins and starches of the flour to absorb water to form gluten and express the viscoelasticity of the dough. In this invention, purified water was selected to be used in a range of 30 to 40 parts by weight per 100 parts by weight of the mixed powder; this is the optimal amount that ensures appropriate dough hardness while ensuring uniform moisture distribution during the low-temperature aging process to stabilize the gluten structure. If the content of purified water is less than 30 parts by weight, the dough becomes too hard, resulting in poor workability, and the gluten may develop excessively during the low-temperature aging process, making the dough tough; if it exceeds 40 parts by weight, the dough becomes excessively soft, making shaping difficult and potentially leading to excessive oil absorption during frying. The reason for selecting purified water is to prevent chlorine or other impurities that may be present in tap water from inhibiting yeast activity or adversely affecting the flavor of the dough, and using high-purity purified water ensures consistent quality.

[0057] Whipping cream provides a soft texture and rich flavor to the dough, while its milk fat appropriately regulates gluten formation, thereby maximizing the softness of the donut. In this invention, the whipping cream was selected to be used in a range of 8 to 12 parts by weight per 100 parts by weight of mixed powder; this is the optimal content that imparts a moist texture and creamy flavor to the donut without weakening the structure of the dough. The milk fat contained in the whipping cream coats gluten proteins to suppress excessive gluten formation, thereby ensuring the donut has a soft and tender texture, and through emulsification, ensures that moisture and fat within the dough are stably dispersed. If the whipping cream content is less than 8 parts by weight, the flavor of the donut may be monotonous and the texture may feel somewhat rough; if it exceeds 12 parts by weight, the dough becomes excessively flexible, making it prone to collapsing during shaping and resulting in an excessive oily sensation after frying. The reason for selecting whipping cream is to achieve the quality level of a premium donut by providing a rich milk fat content and a creamy texture that are difficult to achieve with ordinary milk or water alone.

[0058] Corn syrup plays a role in maintaining the moisture of the dough, increasing sweetness, and delaying the staling of the donut. In this invention, corn syrup was selected to be used in a range of 1.5 to 3 parts by weight per 100 parts by weight of the mixed powder. This is the optimal content to increase moisture retention and maintain a moist texture even after thawing, given the characteristics of this invention which involves rapid freezing and thawing processes. Corn syrup has high hygroscopicity and possesses the characteristic of binding and retaining moisture within the product, which contributes to minimizing moisture loss that may occur during the freezing and thawing process. Additionally, corn syrup delays the staling of starch, ensuring that the donut does not harden over time and maintains its softness, while imparting an appropriate sweetness to enhance the palatability of the product. If the corn syrup content is less than 1.5 parts by weight, the moisture retention effect is insufficient, and the donut may feel somewhat dry after thawing; if it exceeds 3 parts by weight, the dough becomes excessively sticky, reducing workability and causing the product to feel overly sweet. The reason for selecting corn syrup is that, unlike sugar, it does not crystallize, stably retains moisture, and provides a soft sweetness.

[0059] Tangzhong is produced by heating flour and water to gelatinize them. It plays a role in significantly increasing the moisture retention capacity of the dough, delaying staling, and maintaining the softness and moistness of the donut for a long time. In this invention, Tangzhong was selected to be used in a range of 8 to 13 parts by weight per 100 parts by weight of the mixed powder, as it was chosen as a key ingredient to preserve quality to the maximum extent during the rapid freezing and thawing processes of this invention. Tangzhong pre-gelatinizes the starch in the flour, causing the starch particles to strongly bind to water. Since the bound moisture does not easily escape during the freezing process, a moist texture is maintained even after thawing. Additionally, Tangzhong improves the viscoelasticity of the dough, facilitating the shaping process and stabilizing the structure of the donut after frying. If the Tangzhong content is less than 8 parts by weight, the moisture retention effect is insufficient, which may lead to quality degradation during the rapid freezing and thawing process; if it exceeds 13 parts by weight, the dough becomes excessively flexible, making it difficult to maintain its shape during shaping and potentially causing the texture to become soft after frying. The reason for selecting Tangzhong is to maintain quality to the maximum extent in the present invention, which undergoes the demanding processes of freezing and thawing, by providing a level of moisture retention and anti-staling effect that is difficult to achieve with general baking methods.

[0060] Butter plays a role in imparting a rich flavor to the dough and aiding gluten formation, while simultaneously creating the soft texture and savory taste of the donut. In this invention, butter is selected to be used in a range of 8 to 12 parts by weight per 100 parts by weight of the mixed powder; this is the optimal content that allows the butter's flavor to permeate evenly throughout the dough during the low-temperature aging process, thereby forming a deep and rich taste. By adding the butter at the final stage of dough mixing and mixing for a sufficient amount of time, it becomes evenly dispersed among the gluten networks, which contributes to making the crumb structure of the donut soft and moist during the frying process. Additionally, the milk fat contained in the butter appropriately controls oil absorption during frying, ensuring that the donut has a rich flavor without being excessively greasy. If the butter content is less than 8 parts by weight, the flavor of the donut may be insufficient and the texture may feel somewhat dry; if it exceeds 12 parts by weight, the dough becomes excessively flexible, which weakens the structure during the low-temperature aging process and may cause the shape to collapse after frying. The reason butter was chosen is that, unlike margarine or shortening, it provides the luxurious flavor characteristic of natural milk fat and is superior in terms of health due to the absence of trans fats; furthermore, the low-temperature aging process allows the butter's flavor components to fully develop, maximizing the quality of the final product.

[0061] As described above, each ingredient used in the present invention was selected to exhibit optimal performance under the specific process conditions of low-temperature aging and rapid freezing. The content range of each ingredient was determined through numerous tests by comprehensively considering the physical properties of the dough, workability, fermentation characteristics, frying characteristics, freezing stability, and the ability to recover quality after thawing. In particular, the combination of tangzhong and corn syrup plays a key role in minimizing quality degradation that may occur during the rapid freezing and thawing process, while the combination of whipped cream and butter is essential for realizing the rich flavor and soft texture of premium donuts. The rationality of such ingredient selection and the optimization of the content range are important technical features that differentiate the present invention from the prior art and serve as the basis for ensuring the excellent quality of the final product.

[0062] Technical reasons, critical significance, and specific implementation methods of the dough preparation step

[0063] The dough preparation step is the most fundamental process in the glazed donut manufacturing method of the present invention, and the quality characteristics that appear in all subsequent process steps are determined at this step. The dough mixing ratio, mixing order, mixing speed and time, and final dough temperature must be controlled very precisely as they have a direct effect on gluten formation, yeast activity, fermentation characteristics, frying quality, and freezing stability.

[0064] Critical significance of the content range of each component

[0065] The content range of each component based on 100 parts by weight of the mix powder is the optimal range derived through numerous tests, and the upper and lower limits of each component are significant as critical points where the physicochemical properties of the dough change rapidly.

[0066] The lower limit of 1.0 part by weight within the range of 1.0 to 1.5 parts by weight of yeast represents the minimum content required for sufficient fermentation to proceed for 20 to 24 hours at a low temperature of 2 to 3 degrees, which is the condition for low-temperature aging. If the yeast content is less than 1.0 part by weight, the metabolic activity of the yeast slows excessively at low temperatures, resulting in insufficient carbon dioxide production during the aging period. Furthermore, the production of byproducts that form fermented flavors, such as alcohol, organic acids, and esters, is insufficient, causing the flavor of the donut to become monotonous and poor. The upper limit of 1.5 parts by weight represents the maximum content required to prevent over-fermentation even under low-temperature conditions. If the yeast content exceeds 1.5 parts by weight, the yeast proliferation rate accelerates even at low temperatures, causing the dough to reach an over-fermented state before 20 hours. Over-fermented dough exhibits problems such as weakened gluten structure, making shaping difficult, collapse of the shape after frying, and an excessive sour taste.

[0067] In the range of 30 to 40 parts by weight of purified water, the lower limit of 30 parts by weight is the minimum amount of water required for the protein and starch in the flour to be sufficiently hydrated to form gluten and for the dough to have appropriate flexibility. If the purified water content is less than 30 parts by weight, the dough becomes excessively hard and stiff, preventing the gluten from forming evenly during the mixing process. Furthermore, the dough is prone to tearing when rolled out, and the quality deteriorates due to uneven moisture distribution during the low-temperature fermentation process. Additionally, if there is insufficient water, the moisture retention effect of the tangzhong is not properly exerted, leading to the problem of the dough drying out during the freezing and thawing process. The upper limit of 40 parts by weight is the maximum amount of water required for the dough to maintain appropriate hardness while allowing for shaping. If the purified water content exceeds 40 parts by weight, the dough becomes excessively soft and sticky, making dividing and shaping difficult. Additionally, the dough spreads during the low-temperature fermentation process, and during frying, excessive water causes oil to splatter, prolongs the frying time, and increases oil absorption, resulting in a greasy texture.

[0068] In the range of 8 to 12 parts by weight of whipping cream, the lower limit of 8 parts by weight is the minimum content that provides a soft and moist texture to the donut while allowing the flavor to be felt as a premium product. If the whipping cream content is less than 8 parts by weight, the gluten-relaxing effect of the milk fat is insufficient, so the texture of the donut feels somewhat rough and hard, and the creamy flavor is weak, making it less distinct from ordinary donuts. The upper limit of 12 parts by weight is the maximum content that allows the benefits of milk fat to be fully utilized while maintaining the structure of the dough. If the whipping cream content exceeds 12 parts by weight, the milk fat excessively inhibits gluten formation, weakening the elasticity of the dough and making it prone to collapsing during molding. Furthermore, after frying, the structure of the donut is weak, causing it to easily squash when picked up by hand, and the excessive greasiness actually lowers the palatability.

[0069] The lower limit of 1.5 parts by weight of corn syrup, within the range of 1.5 to 3 parts by weight, is the minimum amount required to maintain the moisture of the donut even during the rapid freezing and thawing process. If the corn syrup content is less than 1.5 parts by weight, the moisture retention effect is insufficient, causing free water to turn into ice crystals during the freezing process, damaging the cell structure, and after thawing, this moisture leaks out, resulting in a somewhat dry and crumbly texture of the donut. The upper limit of 3 parts by weight is the maximum amount required to provide an appropriate sweetness while maintaining the workability of the dough. If the corn syrup content exceeds 3 parts by weight, the dough becomes excessively sticky, making shaping difficult; during frying, the surface turns brown too quickly, causing the inside to be undercooked; and the sweetness of the product becomes excessive, overlapping with the sweetness of the glaze and cream, thereby disrupting the overall balance of flavor.

[0070] Within the range of 8 to 13 parts by weight of tangzhong, the lower limit of 8 parts by weight represents the minimum content required to maintain quality while undergoing the demanding processes of rapid freezing and thawing. If the tangzhong content is less than 8 parts by weight, the water binding effect of the gelatinized starch is insufficient, resulting in a large amount of free water remaining during the freezing process. This water forms large ice crystals that destroy the cell structure, and significant moisture loss after thawing causes the donut to become dry and hard. The upper limit of 13 parts by weight represents the maximum content that allows for the full utilization of the benefits of tangzhong while maintaining the gluten structure of the dough. If the tangzhong content exceeds 13 parts by weight, the excessive gelatinized starch makes the dough overly flexible and weakens its elasticity; consequently, it becomes difficult to maintain the shape during molding, and problems arise where the texture of the donut becomes soft and tears easily after frying.

[0071] Within the range of 8 to 12 parts by weight of butter, the lower limit of 8 parts by weight is the minimum amount required to ensure that the butter flavor is fully expressed during the cold fermentation process, thereby imparting a deep and rich taste to the donut. If the butter content is less than 8 parts by weight, the savory and smooth flavor characteristic of milk fat is weak, lowering the premium quality of the product; additionally, the gluten-melting effect is insufficient, causing the texture of the donut to feel somewhat rough. The upper limit of 12 parts by weight is the maximum amount that can maximize the butter flavor while maintaining the dough structure. If the butter content exceeds 12 parts by weight, the milk fat excessively inhibits gluten formation, weakening the elasticity of the dough and causing it to spread during the cold fermentation process; furthermore, due to the excessive milk fat, oil absorption increases during frying, making the product feel excessively greasy.

[0072] Technical Reasons and Critical Significance of the Step-by-Step Mixing Process

[0073] In the dough preparation stage, the order in which ingredients are added, as well as the mixing speed and time at each stage, are very important. If ingredients are mixed randomly or all ingredients are added at once, gluten is formed unevenly and each ingredient fails to perform its role, resulting in a significant decrease in the quality of the final product.

[0074] In the first step, add only the mix powder and yeast to the mixer and mix at a low speed for one minute. The purpose of this step is to evenly disperse the powdered ingredients so that hydration proceeds uniformly throughout when water is added later. The mixing speed is set to a low speed to prevent the powder from scattering into the air and to ensure even mixing within the mixer; one minute is the optimal time, sufficient to achieve a perfectly uniform mixture without consuming an unnecessarily long amount of time. If this step is omitted or the mixing time is shorter than 30 seconds, clumps of powder and concentrated yeast will form, resulting in uneven hydration; conversely, if the mixing time exceeds two minutes, it only increases unnecessary energy consumption without any improvement in quality.

[0075] In the second step, purified water, whipping cream, and corn syrup are added to the flour uniformly mixed in the first step, and the dough is hydrated by mixing at a low speed for 2 to 3 minutes. The purpose of this step is to allow the proteins in the flour to absorb water to form gluten precursors and for the starch to hydrate, thereby enabling the dough's viscoelasticity to begin to develop. Purified water and whipping cream are added simultaneously to ensure that the moisture and milk fat work together to properly regulate gluten formation, while corn syrup is added at this stage to ensure it disperses well in the presence of moisture and spreads evenly throughout the dough. The mixing speed is maintained at a low level because rapid mixing during the initial hydration stage can lead to uneven gluten formation and clumping of the dough. The mixing time of 2 to 3 minutes is the time required for all the flour to absorb moisture, eliminate lumps, and for the dough to coalesce into a single mass. If the mixing time is less than 2 minutes, dry flour remains, causing problems in subsequent stages, and if it exceeds 3 minutes, unnecessary mixing proceeds while hydration is already complete, which can cause the dough temperature to rise and lead to excessive gluten formation.

[0076] In the third step, add the tangzhong to the hydrated dough and mix at medium speed for 2 minutes. The purpose of this step is to evenly disperse the gelatinized starch contained in the tangzhong throughout the dough to maximize moisture retention and improve the dough's viscoelasticity. The reason for adding the tangzhong at this stage is that when added after the basic gluten structure has been formed, the gelatinized starch is effectively dispersed between the gluten networks, allowing it to bind moisture strongly without weakening the dough's structure. If the tangzhong is added too early, excessive moisture prevents proper gluten formation; conversely, if added too late, it fails to properly integrate into the already formed gluten structure, reducing its effectiveness. The mixing speed is increased to medium speed because the tangzhong has a sticky nature, making it difficult to infuse evenly into the dough at low speeds. The 2-minute mixing time is sufficient for the tangzhong to be completely dispersed and for the dough's viscoelasticity to improve. If the mixing time is less than 2 minutes, clumps of tangzhong remain, resulting in uneven quality; if it exceeds 2 minutes, excessive mixing may damage the gluten.

[0077] In the fourth step, butter is added to the dough and mixed at medium speed for 8 minutes. The purpose of this step is to fully absorb the butter into the dough while sufficiently developing the gluten to impart appropriate elasticity and extensibility. The reason butter is added last is that milk fat has properties that inhibit gluten formation; therefore, adding it early would result in insufficient gluten formation and a weak dough structure. By adding butter after the basic gluten structure has been formed, the gluten network is already established. This allows the butter to soften the gluten appropriately without completely destroying it, creating a soft yet elastic dough. The mixing speed is maintained at medium speed because appropriate shear force is required for the butter to be absorbed into the dough while in a solid state. The 8-minute mixing time is sufficient for the butter to be fully absorbed and for the gluten to develop to an optimal state. If the mixing time is less than 8 minutes, the butter is not fully absorbed, leaving lumps of butter in the dough, or the gluten development is insufficient, resulting in weak elasticity of the dough; if it exceeds 8 minutes, excessive mixing causes the gluten to break and the dough to become tough, and the dough temperature rises excessively, which has a negative effect on subsequent cold fermentation.

[0078] Critical significance of final dough temperature

[0079] After all mixing is complete, it is very important to measure the temperature of the dough and ensure it is within the range of 25 to 28 degrees. The dough temperature is a key factor in determining the rate of yeast activity and the rate of gluten stabilization during the subsequent cold fermentation stage.

[0080] The lower limit of 25 degrees Celsius is the minimum temperature designed to ensure stable fermentation by allowing yeast to adapt gradually without abruptly ceasing activity at the start of cold aging. If the dough temperature falls below 25 degrees, the dough becomes excessively cold, causing yeast activity to almost cease during the early stages of cold aging. Consequently, insufficient fermentation occurs during the 20 to 24-hour aging period, resulting in a weak flavor profile. The upper limit of 28 degrees Celsius is the maximum temperature set to prevent premature fermentation caused by excessive yeast activation prior to cold aging. If the dough temperature exceeds 28 degrees, the yeast becomes active rapidly at room temperature before being placed in the refrigerator, generating a significant amount of carbon dioxide. This disrupts the balance of the cold aging process, leading to over-fermentation or uneven fermentation. Furthermore, a high dough temperature causes gluten to develop excessively, resulting in tough dough and reduced effectiveness of cold aging.

[0081] There are various ways to control the dough temperature. If the dough temperature is below 25 degrees Celsius after mixing, you can let it sit at room temperature for a while or move it to a warmer place to naturally raise the temperature. If the dough temperature exceeds 28 degrees Celsius, you can place it in the refrigerator for a short time to cool it quickly or use ice water to cool the mixer bowl. Additionally, to ensure the dough temperature is within the appropriate range from the start, it is effective to control the temperature of the ingredients used. By using chilled purified water in the summer and lukewarm water in the winter, you can control the final dough temperature to within the target range.

[0082] Technical reasons, critical significance, and specific implementation methods of the low-temperature aging stage

[0083] The low-temperature aging step is one of the most critical processes of the present invention, and by aging the dough at a low temperature for a long time, it stabilizes the gluten structure, forms a deep fermented flavor, and maximizes the texture of the donut. This step is not merely about keeping the dough cold, but is a highly technical process that enables yeast and enzymes to act slowly at low temperatures, thereby achieving a quality that cannot be achieved through room-temperature fermentation.

[0084] Critical Significance of Dough Division Weight

[0085] Dividing the dough into portions weighing between 2,000 and 2,085 grams prior to cold fermentation represents the optimal weight range considering both the efficiency of cold fermentation and the convenience of subsequent operations. The lower limit of 2,000 grams is the minimum weight that allows for the production of a sufficient quantity of donuts from a single loaf while ensuring that cold air is evenly distributed throughout the dough within the refrigerator. If the dough weight is less than 2,000 grams, the dough loaves become excessively small; this leads to unstable quality due to the surface drying out excessively or reacting sensitively to temperature changes during the cold fermentation process, while also reducing work efficiency. The upper limit of 2,085 grams is the maximum weight that allows cold air to sufficiently reach the center of the dough within the refrigerator, ensuring uniform cold fermentation throughout. If the dough weight exceeds 2,085 grams, the loaves become excessively large, requiring a long time to cool to the center. Furthermore, the temperature difference between the center and the surface results in uneven fermentation speeds and a reduced cold fermentation effect. Additionally, heavy dough is inconvenient to handle and difficult to manage during shaping operations, leading to decreased work efficiency.

[0086] Technical reasons for the dough molding method

[0087] Hand-rolling the divided dough into a smooth sphere is a crucial step for maintaining the dough's structure and minimizing surface drying during the cold fermentation process. Rolling the dough evenly disperses internal air bubbles and aligns gluten fibers in a consistent direction, resulting in a uniform structure for the entire dough. Additionally, shaping it into a sphere minimizes the volume-to-surface ratio, effectively preventing the surface from drying out during cold fermentation. If the dough is left in an irregular shape or is not properly rolled, the surface will be uneven and the air bubble distribution will be irregular, leading to inconsistent quality after cold fermentation. Hand-rolling also creates appropriate tension on the dough surface, preventing it from spreading and helping it maintain its shape during cold fermentation.

[0088] The Importance and Method of Sealing

[0089] Individually sealing shaped dough in plastic bags is an essential measure to prevent surface drying during the cold fermentation process and to block the transfer of odors from other foods in the refrigerator. Due to the low humidity inside the refrigerator, unsealed dough dries out quickly on the surface, forming a hard film; this dry film hinders subsequent shaping and degrades the quality of the final product. Sealing with plastic bags retains the dough's own moisture, keeping the surface moist, while blocking contact with outside air prevents oxidation. When sealing, it is best to remove as much air as possible from the bag to ensure a tight seal between the dough surface and the bag, and the bag must be completely sealed to prevent any external air from entering.

[0090] Critical Significance of Low-Temperature Aging Temperature

[0091] Fermenting the dough at a refrigeration temperature of 2 to 3 degrees is the optimal temperature range for stabilizing the gluten structure while maintaining moderate yeast activity. The lower limit of 2 degrees is the minimum temperature at which yeast metabolic activity proceeds very slowly without completely ceasing. If the fermentation temperature drops below 2 degrees, yeast activity nearly stops, preventing proper fermentation; consequently, sufficient carbon dioxide production and the formation of flavor compounds do not occur during the 20 to 24-hour fermentation period. Furthermore, excessively low temperatures can make the dough overly hard, thereby reducing its workability. The upper limit of 3 degrees is the maximum temperature at which yeast activity is maintained at an appropriately moderate level while preventing over-fermentation. If the fermentation temperature exceeds 3 degrees, the yeast metabolic rate accelerates, potentially leading to an over-fermented state before 20 hours; this weakens the dough's gluten structure and causes an excessive expression of sourness, thereby degrading quality.

[0092] Precise temperature control is necessary because refrigerator temperatures can fluctuate depending on the season, location within the refrigerator, and the frequency of door opening and closing. Ideally, a temperature recorder should be installed inside the refrigerator to continuously monitor the temperature and allow for immediate adjustment if it deviates from the target range. Additionally, it is recommended to place the dough on the middle shelf of the refrigerator to ensure the cold air is maintained most stably.

[0093] The Critical Significance of Low-Temperature Aging Time

[0094] Cold aging the dough for 20 to 24 hours is the optimal time range required for stabilizing the gluten structure and forming fermented flavors. The lower limit of 20 hours represents the minimum time necessary for yeast and enzymes to act at low temperatures to produce a sufficient amount of flavor substances and for the gluten to fully relax and stabilize. If the aging time is less than 20 hours, fermentation is insufficient, resulting in a lack of sufficient flavor components such as alcohol, organic acids, and esters. Additionally, gluten relaxation is incomplete, making the dough somewhat stiff and difficult to shape. Furthermore, the moist and chewy texture, which is the greatest advantage of cold aging, is not properly expressed. The upper limit of 24 hours represents the maximum time to fully enjoy the benefits of cold aging while preventing over-fermentation. If the aging time exceeds 24 hours, yeast activity accumulates even under low-temperature conditions, leading to a state of over-fermentation. Consequently, the dough's pH drops, resulting in an excessive sour taste, and the weakened gluten structure makes shaping difficult. In addition, prolonged aging reduces production efficiency and leads to inefficient use of refrigerator space.

[0095] During the cold fermentation process, yeast slowly metabolizes sugars to produce carbon dioxide and alcohol, proteolytic enzymes properly break down gluten to soften the dough, and lipolytic enzymes break down lipids to enhance flavor. These biochemical changes accumulate over time, with 20 to 24 hours being the timeframe when these changes reach their optimal levels. Another significant effect of cold fermentation is the uniform redistribution of moisture within the dough, ensuring that all parts achieve the same hydration level. This forms the basis for guaranteeing consistent quality during the subsequent shaping, fermentation, and frying processes.

[0096] Technical reasons, critical significance, and specific implementation methods of the molding and fermentation stages

[0097] The shaping and fermentation stage is a process of shaping the cold-aged dough into the final form of a donut and fermenting it sufficiently to prepare it for frying. In this stage, the cold temperature of the cold-aged dough is properly restored, it is shaped to a uniform thickness, and a second fermentation is carried out in an optimal environment to lay the foundation for making soft and fluffy donuts.

[0098] Technical reasons for the dough temperature recovery step

[0099] Taking cold-fermented dough out of the refrigerator and letting it rest at room temperature for 10 to 30 minutes is an essential process for ensuring its workability. Dough stored at a refrigerator temperature of 2 to 3 degrees Celsius is very cold and hard, making it prone to tearing or uneven thickness if rolled out immediately. Leaving it at room temperature for an appropriate amount of time allows the dough's temperature to gradually rise, softening the gluten and restoring its proper extensibility, making it easier to work with.

[0100] The lower limit of 10 minutes is the minimum time required for the dough surface temperature to recover to some extent and ensure minimal workability. If the resting time is less than 10 minutes, the dough is still too cold and hard, resulting in high resistance and a tendency to tear when rolled out; even when using a roller, it is difficult to achieve a uniform thickness. The upper limit of 30 minutes is the maximum time to prevent the dough temperature from rising excessively and causing fermentation to start prematurely. If the resting time exceeds 30 minutes, the surface temperature of the dough becomes excessively high, causing the yeast to become active. This results in partial fermentation occurring before shaping, making it difficult to achieve uniform quality. Additionally, the dough may become excessively flexible, making it difficult to maintain its shape after shaping.

[0101] The dough's temperature recovery time can be adjusted depending on the temperature and humidity of the workroom and the size of the dough. In hot summer environments, about 10 to 15 minutes is appropriate, while in cold winter environments, about 20 to 30 minutes may be required. To check the proper temperature recovery of the dough, lightly press it with your hand and verify that it feels elastic and that the surface is not cold but slightly cool.

[0102] Critical Significance of Dough Rolling Thickness

[0103] Rolling out the dough using a roller to a thickness of 3 to 10 millimeters is a critical process that determines the texture, frying time, and shape stability of the donut. The lower limit of 3 millimeters is the minimum thickness to prevent the donut from becoming excessively thin, resulting in a texture that is merely crispy while losing its soft interior texture. If the dough thickness is less than 3 millimeters, moisture evaporates rapidly during frying, causing the donut to have a hard and crispy cracker-like texture, while the fluffy and moist interior texture disappears, failing to achieve the quality of the donut targeted by this invention. Additionally, very thin dough may easily deform or burst during frying. The upper limit of 10 millimeters is the maximum thickness to ensure that the inside is sufficiently cooked during frying without the surface burning. If the dough thickness exceeds 10 millimeters, the surface quickly turns brown during frying, but the inside remains undercooked; consequently, it becomes difficult for the internal temperature to reach 95 to 98 degrees, and the center may have a texture similar to raw dough. In addition, excessively thick donuts require a longer frying time, which increases oil absorption and can make them feel greasy.

[0104] Using a roller is effective for rolling out the dough to a uniform thickness. Using a roller allows the dough to be rolled with consistent pressure, ensuring that all parts have the same thickness. This guarantees uniform quality by ensuring that all donuts are cooked to the same degree in the same amount of time during frying. It is recommended to attach a thickness control guide to the roller to roll the dough to a precise thickness.

[0105] Precision of donut molding

[0106] Shaping rolled dough into rings using a donut cutter is an efficient method for manufacturing donuts of consistent size and shape. A donut cutter is a tool that cuts both the outer and inner circles simultaneously, allowing for the creation of a perfect ring shape in a single motion. Since the size of the cutter determines the size of the final product, it is important to use cutters of the same specifications to ensure consistent product dimensions. Generally, cutters with an outer diameter of 8 to 10 centimeters and an inner diameter of 2 to 3 centimeters are suitable for making standard-sized donuts.

[0107] When cutting, press the cutter perpendicularly into the dough to make a clean cut in one go. Twisting or pressing the cutter multiple times will result in an uneven cross-section, which may cause the dough to become irregular in shape during the fermentation and frying processes. Leftover dough pieces can be gathered, rolled out, and cut again, but it is recommended not to reuse them more than twice. This is because reusing the dough multiple times can cause the gluten to develop excessively, resulting in tough donuts.

[0108] Critical Significance of Temperature and Humidity in Secondary Fermentation

[0109] Secondary fermentation of the shaped donut dough for 1 to 2 hours in a proofing room maintained at a temperature of 25 to 30 degrees and a humidity of 70 to 80 percent is an essential process to ensure that the donut expands properly and has a soft texture.

[0110] The lower limit of the fermentation temperature, 25 degrees, is the lowest temperature at which yeast begins to become active. If the fermentation temperature is below 25 degrees, the yeast's metabolic rate slows down, preventing sufficient fermentation within two hours. Consequently, the dough's volume increase is insufficient, resulting in donuts that are dense and have a hard texture after frying. The upper limit, 30 degrees, is the maximum temperature at which efficient fermentation can be achieved while preventing over-fermentation. If the fermentation temperature exceeds 30 degrees, yeast activity accelerates excessively, potentially leading to an over-fermented state within one hour. Over-fermented dough has a weakened gluten structure, causing it to collapse during frying and exhibit an excessive sour taste.

[0111] The lower limit of fermentation humidity, 70 percent, is the minimum humidity required to prevent the dough surface from drying out. If the fermentation humidity is below 70 percent, moisture evaporates from the dough surface, forming a hard film; this inhibits the expansion of the dough during fermentation and creates an uneven texture on the surface after frying. The upper limit, 80 percent, is the maximum humidity required to prevent the dough surface from becoming excessively wet. If the fermentation humidity exceeds 80 percent, water droplets form on the dough surface, and the dough becomes excessively wet, making it difficult to maintain its shape; furthermore, during frying, the oil splatters excessively, and the surface does not cook evenly.

[0112] The lower limit of 1 hour for fermentation is the minimum time required for the dough to expand to about 1.5 times its initial thickness. If the fermentation time is less than 1 hour, the fermentation is insufficient, resulting in a donut with a small volume, a dense internal structure, and a hard texture. The upper limit of 2 hours is the maximum time required to achieve the optimal fermentation state while preventing over-fermentation. If the fermentation time exceeds 2 hours, the dough expands excessively, weakening the gluten structure, causing the shape to collapse during frying, and increasing oil absorption.

[0113] Critical Significance of the Criteria for Determining Fermentation Completion

[0114] Completing fermentation when the thickness of the donut dough increases to 1.5 to 2 times its initial thickness is a criterion for objectively judging the proper state of fermentation. The lower limit of 1.5 times represents the level at which the dough achieves minimal expansion to produce a soft texture. If the thickness increase is less than 1.5 times, fermentation is insufficient, resulting in small internal pores, high density, and a hard texture. The upper limit of 2 times represents the level at which maximum softness can be achieved while preventing over-fermentation. If the thickness increase exceeds 2 times, it is considered over-fermented; this weakens the gluten structure, causing the dough to collapse during frying and absorb excessive oil.

[0115] Another way to check if fermentation is complete is to gently press the dough with your finger. Properly fermented dough will slowly return to its original shape when pressed with a finger, leaving a slight indentation. If it springs back immediately when pressed, it is not yet fully fermented, and if the indentation does not recover at all, it is over-fermented.

[0116] Technical reasons, critical significance, and specific implementation methods of the frying step

[0117] The frying stage is the process of cooking the fermented dough in high-temperature cooking oil to complete the final donut. During this stage, the temperature and time must be precisely controlled to ensure the surface is cooked to a crispy golden brown, while the interior is fully cooked to maintain a moist and soft texture.

[0118] The critical significance of frying temperature

[0119] Preheating cooking oil to a temperature of 170 to 180 degrees is the optimal temperature range for cooking donuts evenly within a reasonable time while preventing excessive oil absorption. The lower limit of 170 degrees is the minimum temperature at which cooking begins immediately on the surface upon the dough being added, allowing heat to be transferred to the interior at an appropriate rate. If the frying temperature falls below 170 degrees, the surface of the dough does not solidify quickly upon entry, leading to excessive oil absorption and resulting in a greasy, heavy, and heavy texture. Additionally, lower temperatures prolong the cooking time, which can cause the donuts to become dry and hard. The upper limit of 180 degrees is the maximum temperature to prevent the surface from browning too quickly and leaving the interior undercooked. If the frying temperature exceeds 180 degrees, the surface of the dough turns brown rapidly and may even burn, while the interior remains raw, resulting in uneven cooking. Furthermore, at high temperatures, charred deposits that produce a bitter taste may form on the surface.

[0120] The frying temperature must be maintained constant throughout the cooking process. Since the oil temperature temporarily drops when batter is added, the amount of batter added at one time must be controlled to minimize this temperature drop. Generally, adding more than 10 percent of the oil volume at once causes the temperature to drop excessively, leading to a decline in quality. Additionally, a digital thermometer should be used to continuously monitor the oil temperature, and the heat level should be adjusted as necessary to maintain the target temperature range.

[0121] The critical significance of double-sided frying time

[0122] Putting the fermented dough into preheated cooking oil and frying the first side for 1 minute 30 seconds to 2 minutes, then flipping it over and frying the second side for 1 minute 30 seconds to 2 minutes is the optimal time range to ensure both sides are cooked evenly and to obtain the appropriate color and texture.

[0123] The lower limit of 1 minute 30 seconds for the first frying time is the minimum time required for one side of the batter to be sufficiently cooked to a golden brown and for heat to begin to transfer to the interior. If the first frying time is less than 1 minute 30 seconds, the surface may be flipped before it is properly cooked and the shape may collapse or excessive oil absorption may occur. The upper limit of 2 minutes is the maximum time to prevent the surface from turning excessively brown or burning. If the first frying time exceeds 2 minutes, the surface will turn excessively brown and become hard, and the interior will be overcooked, resulting in moisture loss and a dry texture.

[0124] The second frying is performed for 1 minute 30 seconds to 2 minutes using the same principle to ensure that both sides are cooked evenly. The total frying time is 3 to 4 minutes, during which time the internal temperature of the donut reaches 95 to 98 degrees and is fully cooked.

[0125] Critical significance of internal temperature

[0126] Reaching an internal temperature of 95 to 98 degrees is an important indicator that the dough is fully cooked, microbiologically safe, and not overcooked. The lower limit of 95 degrees is the lowest temperature at which the starch is completely gelatinized and the protein coagulates, resulting in the dough being cooked rather than raw. If the internal temperature is below 95 degrees, the center remains undercooked, resulting in a texture and taste similar to raw dough; furthermore, it is difficult to digest and microbiological safety is not guaranteed. The upper limit of 98 degrees is the maximum temperature at which the dough is fully cooked while preventing excessive moisture loss. If the internal temperature exceeds 98 degrees, excessive moisture evaporates, causing the dough to have a dry and hard texture, and failing to achieve the moist and soft quality targeted by the present invention.

[0127] The internal temperature can be measured by inserting a digital thermometer into the center of the donut. On the production floor, rather than measuring the temperature every time, consistent internal temperatures are achieved by precisely controlling frying time and temperature, and the proper progress of the process is verified by periodically extracting samples to check the internal temperature.

[0128] The Importance of Oil Removal and Cooling

[0129] Removing the fried donuts from the cooking oil, placing them on a wire rack, and cooling them at room temperature for 5 to 10 minutes while removing excess oil from the surface is an essential step to prepare them for quick freezing.

[0130] The lower limit of 5 minutes is the minimum time required for the surface temperature of the donut to drop sufficiently to minimize temperature shock during rapid freezing. If the cooling time is less than 5 minutes, the donut is placed into rapid freezing while its temperature is still too high, which may cause surface cracks or damage to the internal structure due to the sudden temperature change. The upper limit of 10 minutes is the maximum time to prevent the quality of the donut from deteriorating due to excessive cooling. If the cooling time exceeds 10 minutes, the donut may cool excessively, causing the surface crust to harden and moisture to redistribute, which can alter the texture; furthermore, prolonged exposure to the temperature range at risk of microbial growth may lead to hygienic issues.

[0131] The reason for cooling on a wire rack is to allow air to circulate to the bottom of the donut for even cooling and to enable the oil on the surface to drip naturally. If placed on a flat surface, the bottom will not cool properly, causing oil to pool and create a greasy texture.

[0132] Technical reasons, critical significance, and specific implementation methods of the rapid freezing stage

[0133] The rapid freezing step is one of the most core innovative processes of the present invention, which freezes the fried donut at a very low temperature for a short period of time to minimize the size of ice crystals and prevent tissue damage, thereby enabling the quality to be maintained similar to that immediately after frying even after thawing.

[0134] Necessity of cooling before rapid freezing

[0135] Cooling fried donuts at room temperature for 5 to 10 minutes before flash-freezing is an important preparatory step to prevent quality damage caused by rapid temperature changes. Immediately after frying, the internal temperature of the donut is very high, ranging from 95 to 98 degrees. If exposed directly to cryogenic temperatures of -35 to -40 degrees from this high-temperature state, the excessive temperature difference between the surface and the interior can cause rapid shrinkage and cracks on the surface. Furthermore, flash-freezing from a high-temperature state causes water vapor generated inside the donut to condense on the surface to form a layer of ice, which leads to the surface becoming soggy and mushy after thawing.

[0136] When cooled at room temperature for 5 to 10 minutes, the surface temperature of the donut drops to approximately 40 to 50 degrees. At this temperature, the temperature shock during rapid freezing is significantly reduced, and surface cracking is prevented. At the same time, excess oil on the surface is removed during this cooling process, which also improves rapid freezing efficiency.

[0137] Critical Significance of Rapid Freezing Temperature

[0138] Rapid freezing of fried donuts at temperatures between -35°C and -40°C is the optimal temperature range for preserving cell structure by uniformly forming fine ice crystals. The lower limit of -35°C is the minimum temperature at which the moisture inside the dough freezes rapidly, preventing time for large ice crystals to form. If the rapid freezing temperature is higher than -35°C, the freezing speed slows down, causing the free water inside and outside the cells to freeze slowly and grow into large ice crystals. These large ice crystals physically destroy cell membranes and damage the cell contents. Upon thawing, a large amount of moisture and nutrients leak from these damaged cells, causing the donuts to dry out and significantly degrading in quality. The upper limit of -40°C is the optimal temperature that maximizes the rapid freezing effect while considering energy efficiency and equipment load. Lowering the rapid freezing temperature below -40°C may slightly increase the freezing speed, but the effect is minimal; furthermore, it leads to a sharp increase in energy consumption and a greater burden on equipment, resulting in reduced economic feasibility.

[0139] At cryogenic temperatures of -35 to -40 degrees Celsius, the moisture inside the donut freezes very rapidly, causing fine ice crystals to be uniformly distributed inside and outside the cells. These fine ice crystals do not destroy the cell membrane, and the structural integrity of the cell is maintained, allowing the original texture to be restored even after thawing. This is the biggest difference between conventional slow freezing and rapid freezing.

[0140] The Critical Significance of Rapid Freezing Time

[0141] Rapid freezing fried donuts for 25 to 40 minutes is the optimal time range that ensures complete freezing to the center without consuming an unnecessarily long time. The lower limit of 25 minutes is the minimum time required for cold air to penetrate to the center and ensure complete freezing, considering the size of the donut and the initial temperature. If the rapid freezing time is less than 25 minutes, the surface and outer edges of the donut may be completely frozen while the center remains unfrozen; this results in an incomplete freezing state, which can lead to quality degradation during storage. The upper limit of 40 minutes is the maximum time required to maintain production efficiency while ensuring the entire donut, including the center, is completely frozen. If the rapid freezing time exceeds 40 minutes, it results in energy waste and reduced production throughput because the donut is unnecessarily exposed to cryogenic temperatures while being fully frozen.

[0142] The rapid freezing time may be adjusted slightly depending on the size of the donut, the initial temperature, and the performance of the rapid freezing equipment. Large donuts or donuts with a high initial temperature may require nearly 40 minutes, while small donuts or sufficiently cooled donuts may be sufficient in about 25 minutes. The completion of rapid freezing can be checked by inserting a temperature sensor into the center of the donut, and it can be determined that it is completely frozen when the temperature of the center drops to minus 18 degrees or lower.

[0143] Storage conditions after rapid freezing

[0144] Once the flash-frozen fried donuts are frozen, they must be immediately transferred to a freezer at -18 degrees Celsius or below for storage. If flash-frozen donuts are left at room temperature, thawing will begin from the surface, causing the effectiveness of the flash freezing to be lost; therefore, they must be transferred to frozen storage as soon as possible after the flash freezing is complete. The frozen storage temperature must be maintained at -18 degrees Celsius or below. At this temperature, microbial growth is completely inhibited and chemical changes are minimized, allowing the quality to be maintained stably for up to one week.

[0145] When freezing, donuts must be properly packaged to protect them from the dry air inside the freezer. Use airtight containers or packaging specifically designed for freezing to prevent moisture from sublimating on the surface of the donuts (freezing burns) and to block the absorption of odors from other foods inside the freezer.

[0146] Technical reasons, critical significance, and specific implementation methods of the thawing step

[0147] The thawing step is a process for restoring a rapidly frozen fried donut to a usable state, and the present invention provides two thawing methods that can be selected depending on the operating conditions.

[0148] Technical Reasons and Critical Significance of Room Temperature Thawing Methods

[0149] Thawing flash-frozen fried donuts at room temperature of 22 to 26 degrees for more than 12 hours is the most natural and stable thawing method for restoring quality.

[0150] The lower limit of 22 degrees Celsius represents the minimum temperature at which thawing is completed within a reasonable time while minimizing microbial growth. If the thawing temperature is below 22 degrees, the thawing speed becomes excessively slow, and the product may not be fully thawed even after more than 12 hours; conversely, an excessively long thawing process increases the risk of microbial proliferation. The upper limit of 26 degrees Celsius represents the maximum temperature at which thawing proceeds at an appropriate speed while preventing quality degradation caused by rapid temperature changes. If the thawing temperature exceeds 26 degrees, uneven thawing occurs, where the surface of the donut thaws rapidly while the interior remains frozen. Furthermore, excessive condensation on the surface can result in a soggy and mushy texture. Additionally, high temperatures can promote microbial growth, potentially compromising food safety.

[0151] The lower limit of 12 hours for thawing is the minimum time required for the donut to be completely thawed to the center, making it suitable for cream filling and glazing. If the thawing time is less than 12 hours, the surface of the donut may be thawed while the center remains cold or partially frozen; performing post-processing in this state makes cream filling difficult and results in an uneven glaze coating. Thawing at room temperature takes at least 12 hours, and generally, 14 to 16 hours is ideal. Since excessively long thawing times pose a risk of microbial growth, post-processing must be performed immediately or the donut must be refrigerated after thawing is complete.

[0152] The advantage of thawing at room temperature is that the entire donut thaws slowly and uniformly, minimizing temperature gradients, and the quality is preserved to the maximum extent as the fine ice crystals formed during rapid freezing melt and the original cellular structure is restored. Room temperature thawing is a method used when sufficient time is available; if removed from the freezer the evening before and left at room temperature, it will thaw properly by the next morning, allowing for immediate post-processing.

[0153] Technical Reasons and Critical Significance of the Convection Oven Defrosting Method

[0154] Thawing flash-frozen fried donuts in a 180-degree convection oven for 3 minutes is a method to quickly thaw products when you need to prepare them urgently.

[0155] A defrosting temperature of 180 degrees is the optimal temperature that utilizes the convection oven's hot air circulation function to distribute heat evenly across the entire donut without causing the surface to overheat, burn, or dry out. At temperatures lower than 180 degrees, the defrosting time increases, negating the advantage of rapid defrosting, while at temperatures higher than 180 degrees, the surface may overheat, turning brown or hard.

[0156] A thawing time of 3 minutes is the optimal time required for the convection oven's circulating hot air to reach the entire donut and thaw it to the inside. If the thawing time is less than 3 minutes, the surface may thaw but the inside may still be cold or partially frozen, and if it exceeds 3 minutes, the donut may be overheated, resulting in moisture loss and a change in texture.

[0157] The advantage of thawing in a convection oven is that the process is completed in a very short time, allowing for a rapid response to sudden increases in demand or urgent orders. Since a convection oven uses a fan to circulate hot air, heat is distributed evenly to all sides of the donut, resulting in more even thawing compared to a standard oven. However, oven thawing can produce a slightly drier texture than thawing at room temperature, so it is recommended to prioritize thawing at room temperature whenever possible and use oven thawing only in emergency situations.

[0158] Flexibility in selecting thawing methods

[0159] The reason this invention provides two thawing methods is to ensure the flexibility to select the optimal method depending on operational conditions and available time. Under planned production schedules, room temperature thawing is used to achieve the highest quality, while oven thawing allows for a rapid response in the event of unexpected increases in demand or urgent orders. This flexibility is a critical competitive advantage in the highly volatile business environment of the bakery industry.

[0160] After thawing, donuts must be immediately processed or stored in a refrigerator at 2 to 4 degrees to prevent microbial growth. If thawed donuts are left at room temperature for a long time, microorganisms may multiply rapidly, potentially causing food safety issues; therefore, it is recommended to complete processing or refrigerate them within 2 hours of thawing.

[0161] Technical reasons, critical significance, and specific implementation methods of the post-processing stage

[0162] The post-processing step is a process of injecting cream into the thawed fried donuts and coating them with glaze to complete the final product, the glazed donut. In this invention, separating the post-processing step after rapid freezing and thawing is a key strategy to maximize production efficiency and ensure flexibility in inventory management.

[0163] Technical method of cream injection

[0164] Cream filling is the process of inserting an injector into the side or bottom of a donut to fill the internal space with an appropriate amount of cream. The most common injection location is the center of the side of the donut, as injecting from this position allows the cream to spread evenly throughout the entire interior. The tip of the injector must be rounded rather than pointed to inject the cream without damaging the internal structure of the donut.

[0165] Various types of cream can be selected, such as custard cream, fresh cream, chocolate cream, and fruit cream, and the choice is determined by the product concept and consumer preferences. Since the viscosity of the cream significantly affects the filling process, it must be adjusted to an appropriate consistency; if it is too runny, it will flow out of the donut, and if it is too thick, filling will be difficult. Generally, maintaining the cream temperature between 4 and 10 degrees Celsius ensures the appropriate viscosity while facilitating the filling process.

[0166] The amount of cream injected varies depending on the size of the donut, but generally, about 15 to 25 grams per donut is appropriate. If the amount is too small, the cream lacks presence, leading to decreased consumer satisfaction; if it is too large, the donut becomes heavy and the cream spills out, ruining the appearance. The trick to injecting the appropriate amount is to inject the cream under constant pressure and stop when the donut feels like it is expanding slightly.

[0167] Technical method of glaze coating

[0168] Glaze coating is the process of applying a sugar coating to the top surface of a donut to give it a glossy appearance and a sweet taste. Glaze is primarily made with powdered sugar and water, and flavors can be enhanced by adding ingredients such as vanilla extract or lemon juice. The consistency of the glaze affects the thickness and appearance of the coating, so it must be controlled precisely. Generally, the ideal consistency is one that flows slowly when scooped with a spoon.

[0169] There are two main methods for glaze coating. The first method is the dipping method, where the top surface of the donut is briefly dipped into the glaze solution; this method allows for a fast and even coating. The second method involves pouring the glaze onto the surface of the donut using a spoon or ladle, which allows for precise control of the amount of glaze.

[0170] After coating with glaze, place the donuts on a wire rack and allow the excess glaze to naturally drip down. The glaze will harden at room temperature for about 10 to 15 minutes to form a glossy surface, at which point the product is finished. You can create various variations by sprinkling toppings such as chocolate chips, nuts, or coconut flakes before the glaze completely hardens.

[0171] Strategic Significance of Separating Post-Processing Stages

[0172] In this invention, separating the post-processing step after rapid freezing and thawing provides several significant advantages. First, since semi-finished products, including those completed up to frying, can be mass-produced and stored via rapid freezing at a central production facility, complex processes requiring skilled personnel can be efficiently concentrated. Second, since each store only needs to thaw the required quantity at the necessary time and perform simple post-processing, the workload on the store is significantly reduced, and even unskilled personnel can easily perform the work. Third, by adding cream and glaze during the post-processing stage, these ingredients do not undergo freezing and thawing processes, ensuring that their quality is maintained at its highest level. If cream and glaze were added and frozen immediately after frying, quality issues such as the cream separating or the glaze melting could occur after thawing. Fourth, since stores can select and use various types of cream and glaze, product diversity can be ensured by creating various variations from the same semi-finished product.

[0173] As described above, each step of the present invention applies optimized conditions and methods based on scientific principles and actual experience, and the condition range of each step has critical significance for simultaneously achieving quality and efficiency. Through such precise process control, the present invention achieves the flavor of low-temperature aging, quality preservation of rapid freezing, operational flexibility of multi-stage thawing, and production efficiency of post-processing separation, thereby providing an innovative manufacturing method for the bakery industry.

[0174] Examples

[0175] To verify the effects of the present invention, examples and comparative examples were performed as follows. The examples were manufactured under conditions that satisfied all constituent requirements of the present invention, while the comparative examples were manufactured by modifying or omitting some of the constituent requirements of the present invention, thereby clarifying the effects of the technical features of the present invention.

[0176] Examples 1 to 3: Preparation of Glazed Donuts According to Dough Mixing Ratios

[0177] Example 1 was prepared by using an intermediate value within the dough mixing ratio range of the present invention, Example 2 was prepared by using a lower limit value of each component, and Example 3 was prepared by using an upper limit value of each component.

[0178] Dough formulation ratios of Examples 1 to 3 ingredient Example 1 Example 2 Example 3 unit Mix powder 100 100 100 weight part East 1.25 1.0 1.5 weight part purified water 35 30 40 weight part whipped cream 10 8 12 weight part corn syrup 2.25 1.5 3 weight part Tangjong 10.5 8 13 weight part butter 10 8 12 weight part

[0179] In Example 1, 1.25 parts by weight of yeast, 35 parts by weight of purified water, 10 parts by weight of whipping cream, 2.25 parts by weight of corn syrup, 10.5 parts by weight of tangzhong, and 10 parts by weight of butter were used for every 100 parts by weight of mixed powder. First, the mixed powder and yeast were placed in a mixer and mixed at low speed for 1 minute to uniformly disperse the ingredients. Next, purified water, whipping cream, and corn syrup were added and mixed at low speed for 2 minutes and 30 seconds to hydrate the dough. Next, tangzhong was added and mixed at medium speed for 2 minutes to improve the viscoelasticity of the dough. Finally, butter was added and mixed at medium speed for 8 minutes to absorb the butter and form gluten. After mixing was completed, the temperature of the dough was measured and confirmed to be 26.5 degrees. The prepared dough was divided into 2040-gram portions, rolled by hand to form a sphere, sealed in a plastic bag, and aged at a low temperature of 2.5 degrees for 22 hours. The cold-aged dough was removed from the refrigerator and left at room temperature for 20 minutes. It was then rolled out to a thickness of 6 millimeters using a roller and shaped into rings using a donut cutter. The shaped donut dough was subjected to a second fermentation for 1 hour and 30 minutes in a fermentation chamber maintained at 27.5 degrees Celsius and 75 percent humidity. Fermentation was completed when the thickness increased to 1.8 times its initial thickness. The fermented dough was placed in cooking oil preheated to 175 degrees Celsius, fried on the first side for 1 minute and 45 seconds, flipped over, and fried on the second side for 1 minute and 45 seconds until the internal temperature reached 96.5 degrees Celsius. The fried donuts were placed on a wire rack and cooled at room temperature for 7 minutes and 30 seconds, after which they were flash-frozen at a freezing temperature of -37.5 degrees Celsius for 32 minutes and 30 seconds. The flash-frozen fried donuts were thawed at room temperature of 24 degrees for 13 hours, then cream was injected and a glaze was coated to complete the final product.

[0180] In Example 2, dough was prepared using 1.0 part by weight of yeast, 30 parts by weight of purified water, 8 parts by weight of whipping cream, 1.5 parts by weight of corn syrup, 8 parts by weight of tangzhong, and 8 parts by weight of butter, relative to 100 parts by weight of mixed powder, with each component having a lower limit value. The mixing process was performed in the same manner as in Example 1, and the final dough temperature was 25.5°C. The prepared dough was divided into 2,000-gram portions, shaped, and then aged at a low temperature of 2°C for 20 hours. After leaving the aged dough at room temperature for 25 minutes, it was rolled out to a thickness of 3 millimeters and shaped. It was subjected to a second fermentation for 2 hours at a temperature of 25°C and 70 percent humidity, and the fermentation was completed when the thickness increased 1.5 times. The first side was fried in edible oil at 170°C for 2 minutes and the second side for 2 minutes to reach an internal temperature of 95°C. After cooling at room temperature for 5 minutes, it was flash-frozen at minus 35 degrees for 40 minutes. Thawing was performed in a convection oven at 180 degrees for 3 minutes, and then post-processing was carried out to complete the final product.

[0181] In Example 3, dough was prepared using 1.5 parts by weight of yeast, 40 parts by weight of purified water, 12 parts by weight of whipping cream, 3 parts by weight of corn syrup, 13 parts by weight of tangzhong, and 12 parts by weight of butter, based on 100 parts by weight of mixed powder, with the upper limit of each component. The mixing process was performed in the same manner as in Example 1, and the final dough temperature was 27.5°C. The prepared dough was divided into 2085-gram portions, shaped, and then aged at a low temperature of 3°C for 24 hours. After leaving the aged dough at room temperature for 10 minutes, it was rolled out to a thickness of 10 millimeters and shaped. It was subjected to a second fermentation for 1 hour at a temperature of 30°C and 80 percent humidity, and the fermentation was completed when the thickness doubled. The first side was fried in 180-degree cooking oil for 1 minute 30 seconds and the second side for 1 minute 30 seconds until the internal temperature reached 98 degrees. After cooling at room temperature for 10 minutes, it was flash-frozen at minus 40 degrees for 25 minutes. Thawing was performed at room temperature of 22 degrees for 15 hours, followed by post-processing to complete the final product.

[0182] Comparative Examples 1 to 4: Preparation of glazed donuts outside the range of dough mixing ratios

[0183] Comparative Examples 1 to 4 confirmed the critical significance of the formulation ratio of the present invention by manufacturing glazed donuts under conditions outside the range of the formulation ratio of the present invention.

[0184] Dough mixing ratios of Comparative Examples 1 to 4 ingredient Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 unit Mix powder 100 100 100 100 weight part East 0.7 2.0 1.25 1.25 weight part purified water 35 35 25 45 weight part whipped cream 10 10 10 10 weight part corn syrup 2.25 2.25 2.25 2.25 weight part Tangjong 10.5 10.5 5 16 weight part butter 10 10 10 10 weight part

[0185] In Comparative Example 1, the yeast content was set to 0.7 parts by weight, which is lower than the lower limit of 1.0 parts by weight of the present invention, and the remaining ingredients were used in the same way as in Example 1. The dough preparation process was carried out in the same manner as in Example 1, and the dough was aged at a low temperature of 2.5 degrees for 22 hours. However, due to the insufficient yeast content, fermentation proceeded insufficiently during the low-temperature aging period, and sufficient expansion did not occur even during the subsequent secondary fermentation. The donuts produced after frying had a small volume, a dense internal structure, and a hard texture.

[0186] In Comparative Example 2, the yeast content was set to 2.0 parts by weight, which is higher than the upper limit of 1.5 parts by weight of the present invention, and the remaining ingredients were used in the same way as in Example 1. The dough preparation process was carried out in the same manner as in Example 1, but during low-temperature aging at 2.5 degrees for 22 hours, yeast activity proceeded excessively, reaching an over-fermented state. The over-fermented dough had a weakened gluten structure, making it difficult to maintain its shape during molding; after frying, the shape of the donut collapsed irregularly, and an excessive sour taste was expressed.

[0187] In Comparative Example 3, the purified water content was set to 25 parts by weight, which is lower than the lower limit of 30 parts by weight of the present invention, and the tangzhong content was set to 5 parts by weight, which is lower than the lower limit of 8 parts by weight of the present invention, while the remaining ingredients were used in the same way as in Example 1. Due to a lack of moisture during the dough preparation process, the dough was excessively hard and stiff, and gluten was not formed evenly during the mixing process. The dough was prone to tearing when rolled out after low-temperature aging, and the donuts exhibited a dry and hard texture after undergoing the rapid freezing and thawing process.

[0188] In Comparative Example 4, the purified water content was set to 45 parts by weight, which is higher than the upper limit of 40 parts by weight of the present invention, and the tangzhong content was set to 16 parts by weight, which is higher than the upper limit of 13 parts by weight of the present invention, while the remaining ingredients were used in the same way as in Example 1. During the dough preparation process, the excessive moisture and tangzhong resulted in the dough being excessively soft and sticky, making dividing and shaping operations very difficult. During the low-temperature aging process, the dough spread out, and during frying, the excessive moisture increased oil absorption, resulting in a greasy texture.

[0189] Examples 4 to 6: Preparation of Glazed Doughnuts According to Low-Temperature Aging Conditions

[0190] In Examples 4 to 6, different low-temperature aging conditions were applied to verify the effect of the low-temperature aging temperature and time conditions of the present invention on the quality of the final product. The dough formulation ratios were all used identically to those in Example 1, and the dough manufacturing process was also performed identically.

[0191] Low-temperature aging conditions of Examples 4 to 6 division Low temperature aging temperature Low-temperature aging time Example 4 2 degrees 20 hours Example 5 2.5 degrees 22 hours Example 6 3 degrees 24 hours

[0192] In Example 4, the dough was aged at a low temperature of 2 degrees for 20 hours. This is the lower limit condition for the low temperature and time of aging according to the present invention. Under these conditions, yeast activity proceeded very slowly, and after 20 hours, the dough had an appropriate fermented flavor and the gluten structure was stabilized. Subsequently, the molding, fermentation, frying, rapid freezing, and thawing processes were performed in the same manner as in Example 1, and the final product exhibited a moist and chewy texture and a subtle fermented aroma.

[0193] In Example 5, the dough was cold-aged at a refrigerated temperature of 2.5 degrees for 22 hours. This is the intermediate condition for the temperature and time of cold aging according to the present invention. Under these conditions, yeast activity proceeded stably, and after 22 hours, the dough had a rich fermented flavor and a highly stabilized gluten structure. The subsequent process was carried out in the same manner as in Example 1, and the final product exhibited a deeper flavor and superior texture compared to Example 4.

[0194] In Example 6, the dough was cold-aged at a refrigerated temperature of 3 degrees for 24 hours. This is the upper limit condition for the temperature and time of cold aging according to the present invention. Under these conditions, yeast activity proceeded somewhat faster than in Examples 4 and 5, but did not reach over-fermentation, and after 24 hours, the dough had a sufficient fermented flavor and the gluten structure was stabilized. The subsequent process was carried out in the same manner as in Example 1, and the final product exhibited a quality similar to that of Examples 4 and 5.

[0195] Comparative Examples 5 to 8: Preparation of glazed donuts outside the low-temperature aging condition range

[0196] In Comparative Examples 5 to 8, glazed donuts were prepared under conditions outside the low-temperature aging temperature and time range of the present invention to confirm the critical significance of the low-temperature aging conditions of the present invention. The dough mixing ratios were all used identically to those in Example 1.

[0197] Low-temperature aging conditions of Comparative Examples 5 to 8 division Low temperature aging temperature Low-temperature aging time Comparative Example 5 1 degree 22 hours Comparative Example 6 5 degrees 22 hours Comparative Example 7 2.5 degrees 15 hours Comparative Example 8 2.5 degrees 30 hours

[0198] In Comparative Example 5, the dough was aged at a low temperature of 1 degree for 22 hours. This is a temperature condition lower than 2 degrees, which is the lower limit of the present invention. Under these conditions, yeast activity was almost completely stopped, so sufficient fermentation did not occur for 22 hours, and a weak fermented flavor was formed. The donuts produced after frying had a monotonous flavor and a somewhat hard texture due to insufficient fermentation.

[0199] In Comparative Example 6, the dough was aged at a low temperature of 5 degrees for 22 hours. This is a temperature condition higher than 3 degrees, which is the upper limit of the present invention. Under these conditions, yeast activity became excessively rapid, reaching an over-fermented state after 22 hours. The over-fermented dough exhibited an excessive sour taste, and the gluten structure was weakened, making shaping difficult; furthermore, the shape of the donut collapsed irregularly after frying.

[0200] In Comparative Example 7, the dough was aged at a low temperature of 2.5 degrees for 15 hours. This is a shorter time condition than the lower limit of 20 hours of the present invention. The aging time of 15 hours was insufficient for fermentation to proceed sufficiently, the generation of fermented flavor components was insufficient, and the relaxation of gluten was incomplete. The donuts produced after frying had a weak flavor and the dough had a somewhat stiff texture.

[0201] In Comparative Example 8, the dough was aged at a low temperature of 2.5 degrees for 30 hours. This is a longer time condition than the upper limit of 24 hours of the present invention. Due to the long aging period of 30 hours, yeast activity accumulated even under low temperature conditions, reaching a state of over-fermentation; the acidity of the dough increased, resulting in an excessive sour taste, and the gluten structure was weakened, making it difficult to mold.

[0202] Examples 7 to 9: Preparation of Glazed Doughnuts According to Rapid Freezing Conditions

[0203] In Examples 7 to 9, different rapid freezing conditions were applied to verify the effect of the rapid freezing temperature and time conditions of the present invention on the quality of the donuts thawed after frozen storage. The dough mixing ratio and low-temperature aging conditions were all used identically to those in Example 1, and all processes up to frying were also performed identically.

[0204] Rapid freezing conditions of Examples 7 to 9 division Quick freezing temperature Quick freezing time Example 7 minus 35 degrees 40 minutes Example 8 minus 37.5 degrees 32 minutes Example 9 minus 40 degrees 25 minutes

[0205] In Example 7, the fried donut was cooled at room temperature for 7 minutes and then quenched at a freezing temperature of -35 degrees for 40 minutes. These are the lower limit temperature and upper limit time conditions for quenching according to the present invention. Under these conditions, the moisture inside the donut froze sufficiently quickly to form fine ice crystals, and after 40 minutes, the center of the donut was completely frozen. After storing the quenched donut at -18 degrees for 5 days and then thawing it at room temperature for 13 hours for post-processing, the donut maintained a moist and soft texture after thawing.

[0206] In Example 8, the fried donut was cooled at room temperature for 7 minutes and then quenched at a freezing temperature of -37.5°C for 32 minutes. This is an intermediate condition for the quenching temperature and time of the present invention. Under these conditions, the moisture inside the donut froze very quickly, forming finer ice crystals, and after 32 minutes, the center of the donut was completely frozen. After storing the quenched donut at -18°C for 5 days and then thawing and post-processing it, the donut maintained a superior texture and consistency after thawing compared to Example 7.

[0207] In Example 9, the fried donut was cooled at room temperature for 7 minutes and then quenched at a freezing temperature of minus 40 degrees for 25 minutes. These are the upper limit temperature and lower limit time conditions of the present invention. Under these conditions, the moisture inside the donut froze most rapidly, forming the finest ice crystals, and the center of the donut was completely frozen within 25 minutes. After storing the quenched donut at minus 18 degrees for 5 days and then thawing and post-processing it, the donut maintained a quality similar to or slightly better than that of Examples 7 and 8.

[0208] Comparative Examples 9 to 12: Preparation of glazed donuts outside the rapid freezing condition range

[0209] In Comparative Examples 9 to 12, glazed donuts were manufactured under conditions outside the rapid freezing temperature and time range of the present invention, or the rapid freezing process was omitted to confirm the critical significance of the rapid freezing conditions of the present invention. The dough mixing ratio, low-temperature aging conditions, and the process up to frying were all performed in the same manner as in Example 1.

[0210] Freezing conditions of Comparative Examples 9 to 12 division Freezing temperature Freezing time note Comparative Example 9 minus 30 degrees 50 minutes Low rapid freezing temperature Comparative Example 10 minus 45 degrees 25 minutes High rapid freezing temperature Comparative Example 11 minus 18 degrees 3 hours General Freezer Comparative Example 12 No freezing Not applicable Freezing omitted

[0211] In Comparative Example 9, the fried donut was cooled at room temperature for 7 minutes and then frozen at a freezing temperature of minus 30 degrees for 50 minutes. This is a temperature condition higher than minus 35 degrees, which is the lower limit of the present invention. Minus 30 degrees is a temperature that is not sufficient to obtain a rapid freezing effect, and because the freezing speed is slow, the moisture inside the donut froze slowly, forming relatively large ice crystals. As a result of storing the rapid-frozen donut at minus 18 degrees for 5 days and then thawing and post-processing it, a large amount of moisture leaked out of the donut after thawing, and the texture changed to be somewhat dry and rough.

[0212] In Comparative Example 10, the fried donut was cooled at room temperature for 7 minutes and then rapidly frozen at a freezing temperature of minus 45 degrees for 25 minutes. This is a temperature condition lower than minus 40 degrees, which is the upper limit of the present invention. Although rapid freezing at minus 45 degrees achieved quality similar to that of Example 9, energy consumption increased sharply and the burden on the equipment increased, resulting in significantly reduced economic feasibility. While the effect of quality improvement was minimal, the increase in cost was significant, leading to reduced practicality.

[0213] In Comparative Example 11, fried donuts were cooled at room temperature and then slow-frozen for 3 hours at -18 degrees Celsius, which is the temperature of a standard freezer. This is a standard freezing method, not rapid freezing. In slow freezing at -18 degrees Celsius, the freezing speed is very slow, so the moisture inside the donuts froze slowly and grew into large ice crystals, and these large ice crystals physically destroyed the cell membranes. As a result of storing the frozen donuts at -18 degrees Celsius for 5 days and then thawing and post-processing them, a large amount of moisture and nutrients leaked out from the damaged cells during thawing, causing the donuts to have a very dry and crumbly texture, and the quality was significantly degraded.

[0214] In Comparative Example 12, the fried donuts were not frozen but immediately filled with cream and coated with glaze to complete the final product. This is a traditional same-day production and same-day sales method. Although the product immediately after production exhibited excellent quality, it was impossible to store, so there was a constraint that it had to be sold immediately after production, and no flexibility in production planning was secured. Furthermore, it was not possible to achieve the efficiency of central production and distributed store production.

[0215] Examples 10 to 11: Preparation of glazed donuts according to thawing method

[0216] In Examples 10 and 11, different thawing methods were applied to verify the effect of the multi-stage thawing method of the present invention on the quality of the final product. The dough mixing ratio, low-temperature aging conditions, and rapid freezing conditions were all used in the same way as in Example 1, and the rapid-frozen donuts were thawed after being stored at minus 18 degrees for 5 days.

[0217] Thawing conditions of Examples 10 to 11 division Thawing method Thawing temperature Thawing time Example 10 Thaw at room temperature 24 degrees 13 hours Example 11 Oven defrosting 180 degrees 3 minutes

[0218] In Example 10, the flash-frozen fried donuts were naturally thawed at room temperature of 24 degrees for 13 hours. During the room temperature thawing process, the entire donut thawed slowly and uniformly, and as the fine ice crystals formed during flash freezing melted, the original cellular structure was restored. After the thawing was complete, cream was injected and a glaze was coated to complete the final product. As a result, the donut maintained a moist and soft texture and exhibited a quality similar to that immediately after frying.

[0219] In Example 11, a flash-frozen fried donut was rapidly thawed in a 180-degree convection oven for 3 minutes. By utilizing the hot air circulation function of the convection oven, heat was evenly distributed throughout the donut, and thawing was completed in just 3 minutes. After thawing, cream was injected and a glaze was coated to complete the final product. As a result, the donut exhibited a quality similar to that of Example 10, but the surface tended to be slightly drier. However, it was confirmed that it can be usefully utilized in emergency situations due to the advantage of being able to prepare the product quickly.

[0220] Comparative Examples 13 to 14: Preparation of glazed donuts outside the thawing condition range

[0221] In Comparative Examples 13 and 14, glazed donuts were prepared using a method outside the range of the thawing conditions of the present invention to confirm the critical significance of the thawing conditions of the present invention. The dough mixing ratio, low-temperature aging conditions, and rapid freezing conditions were all used in the same way as in Example 1, and the rapid-frozen donuts were thawed after being stored at minus 18 degrees for 5 days.

[0222] Thawing conditions of Comparative Examples 13 to 14 division Thawing method Thawing temperature Thawing time note Comparative Example 13 Thaw at room temperature 30 degrees 8 hours High thawing temperature Comparative Example 14 Microwave defrosting High power 2 minutes Improper thawing method

[0223] In Comparative Example 13, a flash-frozen fried donut was thawed at room temperature of 30 degrees for 8 hours. This is a temperature condition higher than the upper limit of 26 degrees of the present invention. Thawing at a high temperature of 30 degrees resulted in uneven thawing, where the surface of the donut thawed rapidly while the interior remained frozen, and excessive condensation formed on the surface, resulting in a soggy and mushy texture. In addition, the high temperature promoted microbial growth, which lowered food safety.

[0224] In Comparative Example 14, a thawed fried donut was defrosted for 2 minutes in the high-power mode of a microwave oven. Since microwave ovens operate by directly heating water molecules inside the food using microwaves, defrosting a thawed donut in a microwave oven resulted in uneven heating between the inside and outside. Some parts were overheated and became hard or dry, while others remained cold, resulting in very uneven defrosting. Furthermore, the strong heating of the microwave oven damaged the texture and structure of the donut, causing a significant deterioration in quality.

[0225] Examples 12 to 14: Preparation of Glazed Donuts According to Comprehensive Process Optimization

[0226] In Examples 12 to 14, glazed donuts suitable for different product concepts were manufactured by comprehensively optimizing each process step of the present invention. Through this, it was confirmed that the manufacturing method of the present invention can be flexibly applied to the development of various products.

[0227] Comprehensive process conditions of Examples 12 to 14 division Dough mixture Low temperature aging Molding thickness Quick freezing Thawing method Product characteristics Example 12 Example 1 2 degrees 20 hours 3 millimeters minus 37.5 degrees 32 minutes 13 hours at room temperature Crispy texture focus Example 13 Example 1 2.5 degrees 22 hours 6.5 millimeters minus 37.5 degrees 32 minutes 13 hours at room temperature Balanced texture Example 14 Example 1 3 degrees 24 hours 10 millimeters minus 37.5 degrees 32 minutes 3 minutes in the oven Soft texture

[0228] In Example 12, to develop a product emphasizing the contrast between a crispy outer crust and a moist interior, the dough was rolled out to a thin thickness of 3 millimeters and shaped. Low-temperature aging was performed at 2 degrees for 20 hours to form an appropriate fermented flavor, and rapid freezing and thawing were performed under the same conditions as in Example 1. Due to its thin thickness, the final product exhibited a contrasting texture with a crispy surface and a moist interior, making it suitable as a product targeting consumers who prefer a light texture.

[0229] In Example 13, to develop a standard product with a balanced texture between the crust and the interior, the dough was rolled out to a medium thickness of 6.5 millimeters and shaped. Low-temperature fermentation was performed at 2.5 degrees for 22 hours to form a rich fermented flavor, and rapid freezing and thawing were performed under the same conditions as in Example 1. The final product had a harmonious balance of crispness in the crust and softness in the interior due to its appropriate thickness, and was suitable as a standard donut preferred by the largest consumer base.

[0230] In Example 14, to develop a premium product emphasizing a soft and fluffy texture, the dough was rolled out to a thickness of 10 millimeters and shaped. Low-temperature fermentation was performed at 3 degrees for 24 hours to form a sufficient fermented flavor, and rapid freezing was performed under the same conditions as in Example 1, but thawing was performed quickly in a convection oven for 3 minutes. Due to the thick thickness, the final product emphasized the soft and fluffy texture inside and was suitable as a product targeting consumers who prefer a premium texture.

[0231] Experimental Example 1: Analysis of Fermented Flavor Components According to Low-Temperature Aging Temperature and Time

[0232] In Experimental Example 1, major flavor components were measured using gas chromatography-mass spectrometry to quantitatively analyze the effects of low-temperature aging temperature and time on the formation of fermented flavor components in the dough. After preparing dough with the formulation ratio of Example 1, different low-temperature aging conditions were applied, and after the aging was completed, dough samples were collected and the content of major fermented flavor components, such as ethanol, acetic acid, and esters, was analyzed.

[0233] Low-temperature aging conditions and sample classification of Experimental Example 1 Sample classification Low temperature aging temperature Low-temperature aging time Experimental Sample 1 2 degrees 20 hours Experimental Sample 2 2.5 degrees 22 hours Experimental Sample 3 3 degrees 24 hours Comparative Sample 1 1 degree 22 hours Comparative Sample 2 5 degrees 22 hours Comparative Sample 3 25 degrees 2 hours

[0234] Experimental sample 1 is dough aged at 2 degrees for 20 hours, corresponding to the lower limit condition of the low-temperature aging temperature and time of the present invention. Experimental sample 2 is dough aged at 2.5 degrees for 22 hours, corresponding to the intermediate condition of the low-temperature aging temperature and time of the present invention. Experimental sample 3 is dough aged at 3 degrees for 24 hours, corresponding to the upper limit condition of the low-temperature aging temperature and time of the present invention.

[0235] Comparative sample 1 is dough aged at a low temperature of 1 degree for 22 hours, corresponding to a condition lower than the lower temperature limit of the present invention. Comparative sample 2 is dough aged at a low temperature of 5 degrees for 22 hours, corresponding to a condition higher than the upper temperature limit of the present invention. Comparative sample 3 is dough aged at 25 degrees for 2 hours using a general room temperature fermentation method, corresponding to a control group to which low temperature aging was not applied.

[0236] For each sample, the content of major fermented flavor components, such as ethanol, acetic acid, ethyl acetate, ethyl butyrate, and isoamyl acetate, was quantitatively analyzed using gas chromatography-mass spectrometry. The analysis results showed that experimental samples 1, 2, and 3 all contained sufficient amounts of fermented flavor components, with experimental sample 2 exhibiting the most balanced flavor profile. Comparative sample 1 had significantly lower flavor component content compared to the experimental samples due to insufficient fermentation caused by the low temperature. Comparative sample 2 underwent over-fermentation due to the high temperature, resulting in an excessively high acetic acid content, which was identified as the cause of an unpleasant sour taste. Comparative sample 3 exhibited a monotonous variety of flavor components formed in a short period due to room-temperature fermentation; although the ethanol content was high, the ester content was low, resulting in a lack of flavor depth.

[0237] Experimental Example 2: Analysis of Changes in Ice Crystal Size and Cell Structure According to Rapid Freezing Temperature

[0238] In Experimental Example 2, cryo-microscope observation and tissue structure analysis were performed to analyze the effect of rapid freezing temperature on the size of ice crystals and cell structure inside the donut. Donuts fried using the same method as in Example 1 were treated under different freezing conditions, ultrathin sections were prepared in the frozen state, and the size and distribution of ice crystals were analyzed by observing them with a cryo-microscope.

[0239] Rapid freezing conditions and sample classification of Experimental Example 2 Sample classification Freezing temperature Freezing time Refrigeration method Experimental Sample 4 minus 35 degrees 40 minutes Quick freezing Experimental Sample 5 minus 37.5 degrees 32 minutes Quick freezing Experimental sample 6 minus 40 degrees 25 minutes Quick freezing Comparative Sample 4 minus 30 degrees 50 minutes Quick freezing Comparative Sample 5 minus 18 degrees 3 hours Slow freezing

[0240] Experimental sample 4 is a donut rapidly frozen at -35 degrees for 40 minutes, corresponding to the lower limit condition of the rapid freezing temperature of the present invention. Experimental sample 5 is a donut rapidly frozen at -37.5 degrees for 32 minutes, corresponding to the intermediate condition of the rapid freezing temperature and time of the present invention. Experimental sample 6 is a donut rapidly frozen at -40 degrees for 25 minutes, corresponding to the upper limit condition of the rapid freezing temperature of the present invention.

[0241] Comparative sample 4 is a donut that was flash-frozen at minus 30 degrees for 50 minutes, which corresponds to a condition higher than the lower temperature limit of the present invention. Comparative sample 5 is a donut that was slow-frozen at minus 18 degrees for 3 hours, which is the temperature of a standard freezer, and corresponds to a control group that did not apply flash freezing.

[0242] As a result of cryo-microscope observation, experimental samples 4, 5, and 6 all showed fine ice crystals with an average diameter of 10 micrometers or less uniformly distributed inside and outside the cells, and the structure of the cell membrane was preserved intact. In particular, experimental sample 6 exhibited the finest ice crystals, although the difference from experimental sample 5 was minimal. Comparative sample 4 had medium-sized ice crystals with an average diameter of approximately 20 micrometers, and minor damage was observed in some cell membranes. Comparative sample 5 had large ice crystals with an average diameter of 50 micrometers or more, and it was confirmed that these large ice crystals physically destroyed the cell membrane, resulting in significant damage to the cell structure.

[0243] After thawing each sample and re-examining the tissue structure, experimental samples 4, 5, and 6 all recovered their cell structures well and maintained a state close to their original texture. Comparative sample 4 experienced some water leakage after thawing due to partial cell damage, but it was not severe. Comparative sample 5 experienced a large amount of water and nutrients upon thawing due to severe cell structure destruction, and the tissue became brittle and dry.

[0244] Experimental Example 3: Measurement of moisture retention and changes in texture according to thawing method

[0245] In Experimental Example 3, moisture content analysis and texture analysis were performed to quantitatively measure the effect of the thawing method on the moisture retention rate and texture of the donut. Donuts that had been fried and flash-frozen in the same manner as in Example 1 were stored at -18°C for 5 days, then thawed using different thawing methods. The moisture retention rate was calculated by measuring the weight change before and after thawing, and hardness, elasticity, cohesiveness, etc. were measured using a texture analyzer.

[0246] Thawing conditions and sample classification of Experimental Example 3 Sample classification Thawing method Thawing temperature Thawing time Experimental Sample 7 Thaw at room temperature 22 degrees 14 hours Experimental Sample 8 Thaw at room temperature 24 degrees 13 hours Experimental Sample 9 Oven defrosting 180 degrees 3 minutes Comparative sample 6 Thaw at room temperature 30 degrees 8 hours Comparative Sample 7 microwave High power 2 minutes Fresh samples No freezing Not applicable Not applicable

[0247] Experimental sample 7 is a donut thawed at room temperature of 22 degrees for 14 hours, corresponding to the lower limit condition of the room temperature thawing temperature of the present invention. Experimental sample 8 is a donut thawed at room temperature of 24 degrees for 13 hours, corresponding to the intermediate condition of the room temperature thawing temperature of the present invention. Experimental sample 9 is a donut thawed in a convection oven at 180 degrees for 3 minutes, corresponding to the oven thawing condition of the present invention.

[0248] Comparative sample 6 is a donut thawed at room temperature of 30 degrees for 8 hours, which corresponds to a condition higher than the upper temperature limit of the present invention. Comparative sample 7 is a donut thawed in the high-power mode of a microwave oven for 2 minutes, which corresponds to an improper thawing method. The fresh sample is a donut immediately after frying without undergoing a freezing process, which corresponds to the reference control group.

[0249] As a result of calculating the moisture retention rate by measuring the weight of each sample before rapid freezing and after thawing, experimental samples 7, 8, and 9 all exhibited a high moisture retention rate of over 95 percent, with samples 7 and 8 showing particularly excellent moisture retention rates of over 97 percent. Experimental sample 9 showed a somewhat lower moisture retention rate of 94 percent, but it was still at a good level. Comparative sample 6 showed a moisture retention rate of 90 percent due to excessive surface condensation caused by uneven thawing. Comparative sample 7 showed a low moisture retention rate of 85 percent due to excessive moisture evaporation in some parts caused by uneven heating.

[0250] Texture analysis results confirmed that experimental samples 7 and 8 exhibited hardness, elasticity, and cohesiveness similar to fresh samples, maintaining their original texture well despite undergoing freezing and thawing processes. Experimental sample 9 showed a somewhat dry texture with a hardness measured slightly higher than that of fresh samples, but it remained at an acceptable level. Comparative sample 6 exhibited a somewhat tough texture due to high hardness and low elasticity. Comparative sample 7 showed a hard and brittle texture with very high hardness and low elasticity, confirming a significant deterioration in quality.

[0251] Experimental Example 4: Tracking Quality Changes According to Frozen Storage Period

[0252] In Experimental Example 4, the freezing storage stability of the donuts produced by the manufacturing method of the present invention was confirmed by tracking quality changes while storing rapid-frozen fried donuts at minus 18 degrees for different periods. Donuts that had been fried and rapidly frozen in the same manner as in Example 1 were stored in a freezer at minus 18 degrees, and samples were collected at 1, 3, 5, and 7 days, respectively, and their quality was evaluated after thawing.

[0253] Frozen storage period and sample classification of Experimental Example 4 Sample classification Frozen storage period Thawing method Experimental sample 10 1 day 13 hours at room temperature Experimental sample 11 3 days 13 hours at room temperature Experimental sample 12 5 days 13 hours at room temperature Experimental sample 13 7 days 13 hours at room temperature

[0254] Experimental sample 10 is a donut stored at -18°C for 1 day after rapid freezing, experimental sample 11 is a donut stored for 3 days, experimental sample 12 is a donut stored for 5 days, and experimental sample 13 is a donut stored for 7 days. All samples were thawed at room temperature of 24°C for 13 hours, then cream was injected and glaze was coated to complete the final product.

[0255] Moisture content, lipid oxidation, microbial count, and sensory evaluation were performed on each sample. The results of the moisture content measurement showed that experimental samples 10, 11, and 12 all maintained similar levels of moisture, and although experimental sample 13 showed a slight decrease, it remained at a good level. Lipid oxidation was evaluated by measuring the peroxide value, and since all samples showed low values ​​within safety standards, it was confirmed that almost no lipid oxidation occurred during the 7-day frozen storage period. Microbial counts were measured for total bacteria and coliforms; since they were either undetectable or detected at very low levels in all samples, it was confirmed that frozen storage at -18°C effectively inhibited microbial growth.

[0256] Sensory evaluation was conducted by 10 trained evaluators, assessing appearance, aroma, taste, texture, and overall preference on a 7-point scale. The evaluation results confirmed that experimental samples 10, 11, and 12 all received high scores of 6 points or higher, indicating that they maintain excellent quality. Experimental sample 13 received a score of approximately 5.5 points, which was slightly lower than that of samples stored for 1 to 5 days, but was still at an acceptable quality level. Through this, it was confirmed that the quality of the donuts produced by the manufacturing method of the present invention is stably maintained even when stored at -18°C for up to 7 days after rapid freezing, and that there is almost no change in quality, particularly during storage periods of 5 days or less.

[0257] Through the above examples, comparative examples, and experimental examples, it was clearly confirmed that the method for manufacturing glazed donuts using rapid freezing and multi-stage thawing according to the present invention can efficiently produce glazed donuts of excellent quality by applying optimized conditions at every process stage, such as the mixing ratio of each ingredient, low-temperature aging conditions, rapid freezing conditions, and thawing methods. In particular, comparative examples that deviated from the constituent requirements of the present invention exhibited problems such as quality degradation, poor workability, and reduced economic efficiency, thereby clearly demonstrating the critical significance of each constituent requirement of the present invention.

[0258] Results and Discussion

[0259] As a result of comprehensively analyzing the results of the examples, comparative examples, and experimental examples regarding the method for manufacturing glazed donuts using rapid freezing and multi-stage thawing of the present invention, it was clearly confirmed that the influence of each component of the present invention on the quality of the final product was clearly confirmed, and in particular, it was proven that the content range of each component and the range of process conditions have critical significance.

[0260] A Study on the Critical Significance of Dough Mixing Ratios

[0261] In Examples 1 to 3, glazed donuts were manufactured using lower, middle, and upper limits for each component within the dough formulation ratio range of the present invention, and excellent quality final products were obtained in all examples. Example 1 exhibited the most balanced formulation ratio by using the middle value for each component and demonstrated optimal performance in all aspects, including dough workability, fermentation characteristics, texture after frying, rapid freezing stability, and quality recovery ability after thawing. Example 2 was able to produce a product of good quality despite using the lower limit for each component, which implies that the lower limit of the present invention is the critical point for ensuring minimum quality. Example 3 was able to produce a product with a richer flavor and softer texture by using the upper limit for each component; however, the increased flexibility of the dough required caution during molding, which implies that the upper limit of the present invention is the limit point for maximizing quality while maintaining workability.

[0262] In contrast, in Comparative Examples 1 to 4, glazed donuts were prepared under conditions outside the range of the dough formulation ratio of the present invention, and serious quality problems occurred in all comparative examples. In Comparative Example 1, the yeast content was set to 0.7 parts by weight, which is lower than the lower limit of 1.0 parts by weight of the present invention. Under these conditions, fermentation proceeded insufficiently during the low-temperature aging period, resulting in a final product with a small volume, a dense internal structure, and a hard texture. This result clearly demonstrates that 1.0 parts by weight of yeast is the minimum content required to achieve sufficient fermentation under low-temperature aging conditions. Since low-temperature aging is carried out at a low temperature of 2 to 3 degrees, the metabolic activity of yeast is very slow; it was experimentally confirmed that at least 1.0 parts by weight of yeast is required to generate sufficient carbon dioxide and form a fermented flavor under these conditions.

[0263] In Comparative Example 2, the yeast content was set to 2.0 parts by weight, which is higher than the upper limit of 1.5 parts by weight of the present invention. Under these conditions, yeast activity proceeded excessively even at low temperatures, reaching a state of over-fermentation. The over-fermented dough had a weakened gluten structure, making it difficult to shape; it also collapsed irregularly after frying and exhibited an excessive sour taste. This result clearly demonstrates that 1.5 parts by weight of yeast is the upper limit for obtaining the maximum fermentation effect while preventing over-fermentation under low-temperature aging conditions. Since low-temperature aging proceeds for a long period of 20 to 24 hours, it was confirmed that if the yeast content is excessive, over-fermentation is reached due to accumulated yeast activity even at low temperatures, which lowers the pH of the dough and excessively decomposes gluten, thereby degrading quality.

[0264] In Comparative Example 3, the purified water content was set to 25 parts by weight and the tangzhong content to 5 parts by weight, using water and tangzhong lower than the lower limit of the present invention. Under these conditions, the dough was excessively hard and stiff, significantly reducing workability, and the donuts exhibited a dry and hard texture after undergoing the rapid freezing and thawing process. This result demonstrates that 30 parts by weight of purified water and 8 parts by weight of tangzhong are the minimum contents required to ensure proper hydration of the dough and rapid freezing stability. Purified water is essential for the hydration of the protein and starch in the flour to form gluten and to express the viscoelasticity of the dough, while tangzhong plays a role in strongly binding water through gelatinized starch to maintain moisture even during the rapid freezing and thawing process. It was confirmed that if these contents are insufficient, the amount of free water inside the dough increases, leading to the formation of large ice crystals during rapid freezing and significant water loss after thawing, resulting in a substantial deterioration in quality.

[0265] In Comparative Example 4, the purified water content was set to 45 parts by weight and the tangzhong content to 16 parts by weight, using higher amounts of water and tangzhong than the upper limit of the present invention. Under these conditions, the dough became excessively soft and sticky, making molding very difficult. Furthermore, during frying, the excessive water content increased oil absorption, resulting in a greasy texture. This result demonstrates that 40 parts by weight of purified water and 13 parts by weight of tangzhong represent the upper limit for maximizing the moisture retention effect while maintaining the workability of the dough. It was confirmed that excessive amounts of water and tangzhong cause the gluten network of the dough to relax excessively, weakening its structural strength. This makes it difficult to maintain the shape during molding and leads to excessive oil absorption during frying.

[0266] Synthesizing these results, it can be seen that the content range of each component of the present invention is precisely set to achieve optimal performance under the special process conditions of low-temperature aging and rapid freezing, and that if this range is exceeded, serious problems arise in one or more aspects of workability, fermentation characteristics, frying quality, and freezing stability. In particular, it has been clearly proven that yeast content is a key factor determining the fermentation speed under low-temperature aging conditions, and that the combination of purified water and tangzhong is a key factor determining quality preservation during the rapid freezing and thawing process.

[0267] A Study on the Critical Significance of Low-Temperature Aging Conditions

[0268] In Examples 4 to 6, glazed donuts were prepared by applying different conditions within the low-temperature aging temperature and time range of the present invention, and excellent quality final products were obtained in all examples. Example 4 was aged for 20 hours at 2°C, which is the lower limit condition for low-temperature aging temperature and time; under this condition, yeast activity proceeded very slowly, forming an appropriate fermented flavor and a stable gluten structure. Example 5 was aged for 22 hours at 2.5°C, which is the intermediate condition, and exhibited the most balanced fermentation characteristics and flavor under this condition. Example 6 was aged for 24 hours at 3°C, which is the upper limit condition; even under this condition, sufficient fermented flavor was formed without reaching over-fermentation.

[0269] In Experimental Example 1, changes in fermented flavor components according to low-temperature aging conditions were quantitatively analyzed using gas chromatography-mass spectrometry. Experimental samples 1, 2, and 3 were all treated under conditions within the low-temperature aging temperature and time range of the present invention, and they all contained sufficient amounts of major fermented flavor components such as ethanol, acetic acid, ethyl acetate, ethyl butyrate, and isoamyl acetate. In particular, experimental sample 2 exhibited the most balanced flavor profile; while maintaining an appropriate ethanol content, the high content of esters resulted in the abundant formation of pleasant fermented aromas such as fruit scents. This result demonstrates that during the low-temperature aging process, yeast slowly metabolizes sugars to produce various flavor components, and that esters, in particular, are effectively formed under low-temperature, long-term fermentation conditions.

[0270] In contrast, in Comparative Examples 5 to 8, glazed donuts were manufactured under conditions outside the low-temperature aging range of the present invention, and quality issues occurred in all comparative examples. In Comparative Example 5, the aging temperature was set to 1 degree, which is lower than the lower limit of 2 degrees of the present invention; under this condition, yeast activity was almost completely halted, and sufficient fermentation did not occur for 22 hours. Consequently, the flavor of the final product was monotonous, and the texture was somewhat hard. The comparative sample of Experimental Example 1, which was a dough aged at 1 degree, had a significantly lower content of fermented flavor components compared to the experimental samples. This result clearly demonstrates that an aging temperature of 2 degrees is the minimum temperature required to achieve sufficient fermentation while allowing yeast to be active gradually, even at low temperatures. It was confirmed that at temperatures below 1 degree, the metabolic activity of yeast approaches a near-cessation state, resulting in insufficient carbon dioxide production and the formation of flavor substances, making it impossible to achieve the deep fermented flavor targeted by the present invention.

[0271] In Comparative Example 6, the aging temperature was set to 5 degrees, which is higher than the upper limit of 3 degrees of the present invention. Under these conditions, yeast activity became excessively rapid, reaching a state of over-fermentation after 22 hours. The over-fermented dough exhibited an excessive sour taste, and its gluten structure was weakened, making it difficult to shape. The dough of the comparative sample from Experimental Example 1, aged at 2 degrees and 5 degrees, was found to have an excessively high acetic acid content, which was identified as the cause of an unpleasant sour taste. This result clearly demonstrates that an aging temperature of 3 degrees is the maximum temperature capable of achieving proper fermentation while preventing over-fermentation even at low temperatures. It was confirmed that at temperatures exceeding 3 degrees, yeast activity accumulates during a long aging process of more than 20 hours, leading to over-fermentation. This excessively lowers the pH of the dough and generates excessive organic acids, resulting in an excessive sour taste.

[0272] In Comparative Example 7, the aging time was set to 15 hours, which is shorter than the lower limit of 20 hours of the present invention. Under these conditions, fermentation was insufficient to proceed adequately, the production of fermented flavor components was insufficient, and gluten relaxation was incomplete. This result demonstrates that an aging time of 20 hours is the minimum time required to achieve sufficient fermentation and gluten stabilization under low-temperature conditions. It was confirmed that during the low-temperature aging process, not only yeast activity but also the proper decomposition and relaxation of gluten by proteolytic enzymes proceeds, and since these changes accumulate over time, an aging time of at least 20 hours is required.

[0273] In Comparative Example 8, the aging time was set to 30 hours, which is longer than the upper limit of 24 hours of the present invention. Under these conditions, due to the long aging period, yeast activity accumulated even under low-temperature conditions, reaching a state of over-fermentation. This result proves that an aging time of 24 hours is the maximum time to prevent over-fermentation while maximizing the effects of low-temperature aging. It was confirmed that long aging exceeding 24 hours reduces production efficiency and leads to inefficient use of refrigerator space, thus reducing practicality.

[0274] Comparative Sample 3 of Experimental Example 1 is a dough aged at 25°C for 2 hours using a standard room temperature fermentation method, serving as a control group without low-temperature aging. In this sample, the types of flavor components formed in a short period were monotonous, and while the ethanol content was high, the ester content was low, resulting in a lack of depth of flavor. This result clearly demonstrates that long-term low-temperature aging forms a much more diverse and complex flavor profile compared to short-term room temperature fermentation. It was confirmed that during the low-temperature aging process, the metabolic rate of yeast slows down, activating various metabolic pathways, which leads to the balanced production of various flavor components such as esters, alcohols, and organic acids.

[0275] Synthesizing these results, it can be seen that the low-temperature aging conditions of the present invention are not merely for keeping the dough cold, but are a highly technical process that precisely controls the activity of yeast and enzymes to form a deep fermented flavor and stabilize the gluten structure. In particular, it has been clearly proven that the temperature range of 2 to 3 degrees is the optimal range for achieving sufficient fermentation while maintaining moderate yeast activity, and the time range of 20 to 24 hours is the optimal range for completing the formation of fermented flavor and gluten stabilization without reaching over-fermentation.

[0276] A Study on the Critical Significance of Rapid Freezing Conditions

[0277] In Examples 7 to 9, glazed donuts were quenched using different conditions within the quenching temperature and time range of the present invention, and all examples showed excellent quality recovery upon thawing after frozen storage. Example 7 was quenched at -35°C for 40 minutes; under these conditions, the moisture inside the donut froze sufficiently quickly, forming fine ice crystals. Example 8 was quenched at -37.5°C for 32 minutes; under these conditions, finer ice crystals were formed due to the faster freezing speed. Example 9 was quenched at -40°C for 25 minutes; under these conditions, the finest ice crystals were formed due to the fastest freezing speed.

[0278] In Experimental Example 2, the size of ice crystals and changes in cell structure according to the rapid freezing temperature were quantitatively analyzed through freezing microscopy observation. Experimental samples 4, 5, and 6 were all treated under conditions within the rapid freezing temperature range of the present invention, and they all exhibited fine ice crystals with an average diameter of 10 micrometers or less. In particular, experimental sample 6 exhibited the finest ice crystals, but the difference from experimental sample 5 was minimal. These fine ice crystals were uniformly distributed inside and outside the cells, and the structure of the cell membrane was preserved intact. As a result of re-observing the tissue structure after thawing, experimental samples 4, 5, and 6 all recovered their cell structures well and maintained a state close to the original texture.

[0279] These results clearly demonstrate the core principles of rapid freezing. Rapid freezing is a technology that causes the moisture inside food to freeze rapidly to form small ice crystals, and the smaller the size of the ice crystals, the less damage is done to the cell membranes, thereby maintaining the quality well after thawing. The rapid freezing temperature range of -35°C to -40°C of the present invention provides a freezing speed sufficient to form fine ice crystals with an average diameter of 10 micrometers or less, and it has been confirmed that this is an essential condition for preserving cell structures and maintaining quality to the maximum extent after thawing.

[0280] In contrast, Comparative Examples 9 to 12 were processed under conditions outside the rapid freezing range of the present invention or the rapid freezing process was omitted, and severe quality degradation occurred in most of the comparative examples. In Comparative Example 9, the rapid freezing temperature was set to -30 degrees, which is higher than the lower limit of -35 degrees of the present invention; under this condition, the freezing speed was slow, resulting in the formation of relatively large ice crystals. Comparative Sample 4 of Experimental Example 2, a donut rapidly frozen at -30 degrees, showed the formation of medium-sized ice crystals with an average diameter of approximately 20 micrometers, and fine damage was observed in some cell membranes. After thawing, some moisture leakage occurred due to partial cell damage, and the texture changed to become somewhat dry and rough. This result clearly demonstrates that a rapid freezing temperature of -35 degrees is the minimum temperature required to form fine ice crystals and preserve the cell structure. While -30 degrees is a temperature achievable in a general industrial rapid freezer, it was confirmed that it is insufficient to maintain quality similar to that immediately after frying, which is the goal of the present invention.

[0281] In Comparative Example 10, the rapid freezing temperature was set to -45 degrees, which is lower than the upper limit of -40 degrees of the present invention. Under these conditions, quality similar to that of Example 9 was achieved, but energy consumption increased rapidly. Since the ultra-low temperature of -45 degrees requires special refrigeration equipment and consumes a significant amount of energy, the effect of quality improvement was minimal, while the increase in costs was significant, resulting in a significant decrease in economic feasibility. This result proves that the rapid freezing temperature of -40 degrees is the optimal upper limit that considers both quality and economic feasibility simultaneously. It was confirmed that temperatures exceeding -40 degrees require expensive equipment that is difficult for small and medium-sized enterprises to operate, and the effect of quality improvement is minimal, resulting in low practicality.

[0282] In Comparative Example 11, the samples were slow-frozen for 3 hours at -18 degrees Celsius, which is the temperature of a standard freezer; this is a conventional freezing method rather than rapid freezing. As the comparative sample of Experimental Example 2 was a donut that was slow-frozen at -18 degrees Celsius, large ice crystals with an average diameter of 50 micrometers or more were formed, and these large ice crystals physically destroyed the cell membranes, causing significant damage to the cell structure. Upon thawing, a large amount of moisture and nutrients leaked out from the damaged cells, resulting in a very dry and crumbly texture of the donut. This result clearly demonstrates the difference between rapid freezing and slow freezing; it was confirmed that slow freezing at -18 degrees Celsius has a very slow freezing speed, allowing sufficient time for ice crystals to grow, which leads to the formation of large ice crystals that destroy cell membranes and significantly degrade quality. The rapid freezing technology of the present invention is a key technology for overcoming the problems of such slow freezing, and it has been clearly proven that freezing at ultra-low temperatures of -35 to -40 degrees for a short period of time minimizes ice crystal size and preserves quality to the maximum.

[0283] In Comparative Example 12, the fried donuts were immediately post-processed without freezing to complete the final product, which is a traditional same-day production and same-day sales method. Although the product immediately after production exhibited excellent quality, it was impossible to store, so there was a constraint that it had to be sold immediately after production, and no flexibility in production planning was secured. This result demonstrates that the rapid freezing technology of the present invention is an innovative technology that goes beyond merely maintaining quality to dramatically improve production efficiency and operational flexibility. It has been confirmed that by applying rapid freezing technology, semi-finished products mass-produced in a central production facility can be frozen and stored for up to a week while maintaining quality, which significantly improves the efficiency of production planning, the flexibility of inventory management, and the speed of response to demand.

[0284] Regarding the rapid freezing time, different times of 40 minutes, 32 minutes, and 25 minutes were applied in Examples 7, 8, and 9, respectively, and in all cases, the center of the donut was completely frozen, achieving a state suitable for frozen storage. This implies that the rapid freezing time has a close correlation with the freezing temperature, requiring a short time at low temperatures and a longer time at relatively high temperatures. The rapid freezing time range of 25 to 40 minutes of the present invention is the time required for complete freezing to the center when considering the size of the donut and the initial temperature, and it was confirmed that excellent quality can be achieved within this range.

[0285] A Study on the Critical Significance of Thawing Methods

[0286] In Examples 10 and 11, rapid-frozen fried donuts were thawed by applying the multi-stage thawing methods of the present invention, namely room temperature thawing and oven thawing, respectively, and both methods demonstrated excellent quality recovery. Example 10 was naturally thawed at a room temperature of 24°C for 13 hours; under these conditions, the entire donut thawed slowly and uniformly, allowing the fine ice crystals formed during rapid freezing to melt and restore the original cellular structure. After thawing was complete, the final product maintained a moist and soft texture and exhibited a quality level similar to that immediately after frying. Example 11 was rapidly thawed in a convection oven at 180°C for 3 minutes; under these conditions, the hot air circulation function of the convection oven was utilized to evenly distribute heat throughout the entire donut. After thawing was complete, the final product exhibited a quality level similar to that of Example 10, but the surface tended to be slightly drier.

[0287] In Experimental Example 3, changes in moisture retention and texture according to the thawing method were quantitatively measured. Experimental samples 7 and 8 were donuts thawed at room temperature, exhibiting an excellent moisture retention rate of over 97 percent. Texture analysis also showed hardness, elasticity, and cohesiveness similar to those of fresh samples. This result demonstrates that thawing at room temperature is the most natural and stable method for restoring quality. It was confirmed that during room temperature thawing, the temperature gradually rises from the surface of the donut, causing ice crystals to melt slowly; in this process, moisture inside the cells is redistributed to its original position, allowing the cell structure to be stably restored.

[0288] Experimental sample 9 was a donut thawed in a convection oven, exhibiting a somewhat low moisture retention rate of 94 percent, but still at a satisfactory level. Texture analysis revealed that the hardness was measured to be slightly higher than that of the fresh sample, indicating a somewhat dry texture, but it was still at an acceptable level. This result demonstrates that while oven thawing produces a slightly drier texture compared to room temperature thawing, it offers the advantage of rapid product preparation, making it useful in emergency situations. It was confirmed that during oven thawing, surface moisture evaporates somewhat due to hot air circulation, but internal moisture is largely preserved due to the short thawing time; this is because the cellular structure is restored as the fine ice crystals formed by rapid freezing melt uniformly.

[0289] In contrast, Comparative Examples 13 and 14 were thawed using methods outside the thawing condition range of the present invention, and quality issues occurred in all comparative examples. In Comparative Example 13, the thawing temperature was set to 30 degrees, which is higher than the upper limit of 26 degrees of the present invention; under this condition, uneven thawing occurred, where the surface of the donut thawed rapidly while the interior remained frozen. Comparative Sample 6 of Experimental Example 3, a donut thawed at 30 degrees, exhibited excessive condensation on the surface, resulting in a soggy and mushy texture, and the moisture retention rate was low at 90 percent. This result clearly demonstrates that a thawing temperature of 26 degrees is the maximum temperature capable of thawing at an appropriate speed while preventing uneven thawing. It was confirmed that thawing at high temperatures creates a large temperature gradient between the surface and the interior, resulting in a state where the surface is already thawed and moist while the interior remains frozen, which degrades quality and increases the risk of microbial growth.

[0290] In Comparative Example 14, the food was defrosted for 2 minutes in the high-power mode of a microwave oven; under these conditions, heating proceeded unevenly between the inside and outside due to the way the microwaves directly heated water molecules inside the food. Comparative Sample 7 of Experimental Example 3 was also a donut defrosted in a microwave oven; some parts were overheated, becoming hard or dry, while others remained cold, resulting in very uneven defrosting. The moisture retention rate was also very low at 85 percent, and texture analysis revealed a hard and brittle texture with very high hardness and low elasticity and cohesiveness. This result clearly demonstrates that a microwave oven is not a suitable method for defrosting rapidly frozen donuts. It was confirmed that because microwaves are absorbed unevenly within the food, problems arise where some parts are overheated while others are underheated, which completely negates the advantages of the uniform micro-ice crystals formed by rapid freezing.

[0291] The purpose of this invention is to provide two thawing methods—room temperature thawing and oven thawing—to ensure the flexibility to select the optimal method depending on operational conditions. Room temperature thawing can be used when sufficient time is available to achieve the highest quality, while oven thawing can be used in emergency situations to prepare products quickly. It has been confirmed that this multi-stage thawing method is a critical competitive factor in the highly volatile business environment of the bakery industry and significantly improves operational efficiency by enabling both planned production and response to urgent demand.

[0292] Consideration on frozen storage stability

[0293] In Experimental Example 4, changes in quality were tracked while storing flash-frozen fried donuts at minus 18°C ​​for different periods. Experimental samples 10, 11, and 12 were donuts frozen for 1, 3, and 5 days, respectively; all maintained similar levels of moisture content, showed low levels of fat oxidation within safety standards, and were either not detected or detected at very low levels. Sensory evaluation results also confirmed that they maintained excellent quality, with all receiving high scores of 6 points or higher. Experimental sample 13 was a donut frozen for 7 days; it received a score of approximately 5.5 points, which was slightly lower than the samples stored for 1 to 5 days, but was still at an acceptable quality level.

[0294] These results demonstrate that the rapid freezing technology of the present invention provides excellent quality stability not only in short-term storage but also in medium-term storage. At a freezing temperature of minus 18 degrees, microbial growth is completely inhibited, and chemical changes are minimized, so quality degradation reactions such as fat oxidation or protein denaturation hardly occur. In particular, it has been confirmed that the fine ice crystals formed by the rapid freezing technology of the present invention undergo minimal size change even during long-term storage, so cell structure damage does not accumulate, and this is the reason why there is almost no change in quality during storage periods of 5 days or less, and acceptable quality can be maintained up to 7 days.

[0295] This frozen storage stability is an important practical value of the manufacturing method of the present invention. Since semi-finished products mass-produced at a central production facility can be frozen and stored for up to a week while maintaining quality, they can be produced in advance during periods of low demand and stored as inventory, and supplied quickly during periods of high demand. It has been confirmed that this maximizes the efficiency of production planning, enables the realization of economies of scale by freeing oneself from the constraints of daily production volume, and provides the flexibility to respond quickly to sudden increases in orders or special events.

[0296] Comprehensive Consideration and Technical Excellence of the Present Invention

[0297] When comprehensively considering the results of all the above embodiments, comparative examples, and experimental examples, it can be seen that the method for manufacturing glazed donuts using rapid freezing and multi-stage thawing according to the present invention is an integrated technical system in which each constituent element is organically linked to produce a synergistic effect. The dough formulation is optimized for low-temperature aging and rapid freezing processes; low-temperature aging forms a deep fermented flavor and a stable gluten structure, rapid freezing preserves the quality thus formed through fine ice crystals, and multi-stage thawing provides operational flexibility while restoring the frozen quality to the maximum extent.

[0298] Of particular note is that each component of the present invention is not merely excellent individually, but is closely linked to one another to create a comprehensive effect. For example, the combination of tangzhong and corn syrup increases the moisture retention of the dough, preventing it from drying out during the low-temperature aging process, while simultaneously minimizing moisture loss during the rapid freezing and thawing processes to preserve quality. Low-temperature aging properly relaxes the gluten, improving the extensibility of the dough; this not only facilitates the shaping process but also increases resistance to temperature stress during rapid freezing, thereby preventing cracking. Rapid freezing preserves the complex flavor components formed through low-temperature aging intact, ensuring that a deep and rich fermented aroma is maintained even after thawing.

[0299] The comparative examples clearly demonstrated that if even one of the constituent requirements of the present invention is deviated from, serious problems arise in one or more aspects of quality, workability, and economic efficiency. This proves that each constituent requirement of the present invention was not selected arbitrarily but was optimized through numerous tests and analyses, and that the numerical range of each constituent requirement has critical significance. In particular, the numerical ranges of 1.0 to 1.5 parts by weight of yeast, 30 to 40 parts by weight of purified water, 8 to 13 parts by weight of tangzhong, 20 to 24 hours of low-temperature aging at 2 to 3 degrees, and 25 to 40 minutes of rapid freezing at minus 35 to minus 40 degrees are all optimal ranges established through scientific grounds and experimental verification, and it was clearly confirmed that the quality and efficiency targeted by the present invention cannot be achieved if these ranges are deviated from.

[0300] Experimental examples quantitatively demonstrated the technical principles of the present invention. Experimental Example 1 demonstrated through gas chromatography analysis that low-temperature aging forms a diverse and complex fermented flavor profile; Experimental Example 2 demonstrated through cryo-microscope observation that rapid freezing forms fine ice crystals to preserve cell structure; Experimental Example 3 demonstrated through quantitative measurements that an appropriate thawing method restores moisture retention and texture to the maximum extent; and Experimental Example 4 demonstrated through tracking investigations over time that the rapid-frozen product maintains stable quality for up to one week.

[0301] The present invention utilizes technology and equipment within a scope that is fully feasible even for small and medium-sized enterprises. Mix powder, yeast, purified water, whipping cream, corn syrup, and butter are all generally available ingredients, and tangzhong can be prepared through a simple cooking process. Low-temperature fermentation can be achieved using a standard commercial refrigerator, rapid freezing can be achieved using an industrial rapid freezer capable of reaching -35 to -40 degrees Celsius, and thawing can be performed at room temperature or in a standard convection oven. Since all of these facilities are at a level generally used in the bakery industry or can be introduced with a reasonable investment, it has been confirmed that the present invention is a practical technology fully applicable even for small and medium-sized enterprises.

[0302] The manufacturing method of the present invention provides various industrial values, such as quality standardization, improved production efficiency, operational flexibility, reduced labor costs, streamlined inventory management, and expanded distribution channels. By performing mass production under precisely controlled process conditions at a central production facility, quality variations that may occur between stores or workers are minimized, enabling the stable supply of products of consistent quality. Since complex dough-making and frying processes requiring skilled personnel are concentrated centrally, and stores perform only simple thawing and post-processing, labor costs can be reduced and operations simplified. Maintaining flash-frozen semi-finished products allows for a rapid response to fluctuations in demand, and the ability to transport products reliably in a frozen state facilitates business expansion to distant stores or new regions.

[0303] In conclusion, the method for manufacturing glazed donuts using rapid freezing and multi-stage thawing according to the present invention is an innovative manufacturing method that integrates four key elements: flavor maximization through low-temperature aging, quality preservation through rapid freezing, operational flexibility through multi-stage thawing, and production efficiency through the separation of post-processing. It has been clearly demonstrated through examples, comparative examples, and experimental examples that this is a scientifically optimized technology in which the numerical range of each component has critical significance. The present invention is a practical and economical technology that simultaneously realizes superior quality and production efficiency, which could not be achieved with the existing same-day production and same-day sales method, and can dramatically improve the competitiveness of the bakery industry.

Claims

Claim 1 A method for manufacturing a glazed donut using rapid freezing and multi-stage thawing, comprising: a) a dough preparation step of preparing a dough having a final dough temperature of 25°C to 28°C by stepwise mixing 100 parts by weight of a mixed powder containing flour, 1.0 to 1.5 parts by weight of yeast, 30 to 40 parts by weight of purified water, 8 to 12 parts by weight of whipping cream, 1.5 to 3 parts by weight of corn syrup, 8 to 13 parts by weight of tangzhong, and 8 to 12 parts by weight of butter; b) a low-temperature aging step of dividing the dough into portions weighing 2000g to 2085g, shaping them, sealing them in a sanitary bag, and aging them at a low temperature for 20 to 24 hours at a refrigeration temperature of 2°C to 3°C; c) leaving the low-temperature aged dough at room temperature, then rolling it out to a thickness of 3mm to 10mm and shaping it into a ring. A shaping and fermentation step of cutting and shaping, and fermenting for 1 to 2 hours under conditions of a temperature of 25°C to 30°C and a humidity of 70% to 80%; d) a frying step of frying both sides of the fermented dough in edible oil at 170°C to 180°C for a total of 3 to 4 minutes to produce a fried donut with an internal temperature of 95°C to 98°C; e) a rapid freezing step of cooling the fried donut at room temperature for 5 to 10 minutes, and then rapidly freezing it at a freezing temperature of -35°C to -40°C for 25 to 40 minutes; f) a thawing step of thawing the rapidly frozen fried donut at room temperature of 22°C to 26°C for 12 hours or more, or thawing it in a convection oven at 180°C for 3 minutes; and g) a post-processing step of injecting cream into the thawed fried donut and coating it with glaze; wherein the a) dough preparation step comprises: a1) a first mixing step of adding the mix powder and the yeast to a mixer and mixing at low speed for 1 minute to uniformly disperse the ingredients; a2) a second mixing step of adding the purified water, the whipping cream, and the corn syrup to the ingredients mixed in the first step and mixing at low speed for 2 to 3 minutes to hydrate the dough;a3) a third mixing step of adding the tangzhong to the hydrated dough and mixing at medium speed for 2 minutes to improve the viscoelasticity of the dough; a4) a fourth mixing step of adding the butter to the dough and mixing at medium speed for 8 minutes to absorb the butter while forming gluten; and a5) a dough temperature checking step of measuring the temperature of the dough after mixing is completed and confirming whether it is within the range of 25°C to 28°C; wherein the b) low-temperature aging step comprises: b1) a dough dividing step of dividing the dough that has undergone the dough preparation step into weights of 2000g to 2085g; b2) a dough shaping step of rolling the divided dough by hand to form a spherical shape with a smooth surface; b3) a sealing step of individually sealing the shaped dough in a sanitary bag; and b4) a cold aging step in which the sealed dough is cold-aged at a refrigeration temperature of 2°C to 3°C for 20 to 24 hours to stabilize the gluten structure and form a fermented flavor; wherein the c) molding and fermentation step comprises: c1) a dough temperature recovery step in which the dough that has undergone the cold aging step is removed from the refrigerator and left at room temperature for 10 to 30 minutes; c2) a dough flattening step in which the dough is rolled out to a thickness of 3 mm to 10 mm using a roller; c3) a donut molding step in which the rolled-out dough is cut into a ring shape using a donut cutter and molded; c4) a secondary fermentation step in which the molded donut dough is secondarily fermented for 1 to 2 hours in a fermentation chamber where a temperature of 25°C to 30°C and a humidity of 70% to 80% are maintained; and c5) a fermentation completion step in which fermentation is completed when the thickness of the donut dough increases to 1.5 to 2 times the initial thickness; characterized by comprising a method for manufacturing a glazed donut using rapid freezing and multi-stage thawing.; Claim 2 delete Claim 3 delete

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