A method for preparing frozen candied hawthorn skewers with a longer shelf life

Abstract

This invention provides a method for preparing frozen candied hawthorn skewers with a longer shelf life, comprising a pretreatment stage of fresh fruit or vegetables, a coating solution preparation and coating stage comprising purified water, sugar, and a thickener, and a two-stage freezing step. According to this invention, the raw materials are pretreated at below 5°C, the coating solution is mixed with purified water and sugar at a weight ratio of 1:2, and a thickener containing agar and konjac is added. The coating material is first frozen at -18°C or lower, and then frozen a second time at -5°C or lower before vacuum packaging, which improves the shelf life and maintains excellent quality even after thawing.

Description

Technical Field

[0001] This invention relates to a method for manufacturing frozen candied hawthorn berries based on fruits or vegetables, and more specifically, to a method for preparing frozen candied hawthorn berries through a raw material pretreatment process, a coating solution preparation and coating process, and a two-stage refrigeration process, as well as a manufacturing method for having a longer shelf life. Background Technology

[0002] Candied hawthorn berries are a traditional snack made by skewering fruits or vegetables and coating them with syrup. Demand has surged in recent years. However, conventional candied hawthorn berries are produced at room temperature, resulting in a short shelf life, uneven sugar coating, and a rapid deterioration of the raw material's freshness. In particular, the sugar coating becomes sticky or melts over time, significantly reducing their marketability.

[0003] Furthermore, existing frozen donut production methods simply involve freezing the manufactured donuts, leading to quality issues such as deterioration of raw material texture and cracking or peeling of the coating layer upon thawing. Additionally, insufficient use of thickeners in the coating liquid manufacturing process results in inadequate coating layer stability.

[0004] Existing technical documents

[0005] Patent documents

[0006] (Patent Document 1) Korean Patent Publication 10-2020-0130898

[0007] (Patent Document 2) Korean Patent No. 10-2021-0034404

[0008] (Patent Document 3) Korean Patent No. 10-2019-0112329

[0009] (Patent Document 4) Korean Patent Registration 10-2567569 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] The present invention aims to solve the problems in the prior art described above and has the following objectives.

[0012] First, we hope to optimize the pre-processing of raw materials to maintain their freshness and texture over the long term.

[0013] Secondly, the aim is to improve the composition and manufacturing method of the coating solution, including purified water, sugar, and thickener, to enhance the stability of the coating layer.

[0014] Third, the two-stage freezing process and vacuum packaging extend the product's shelf life, ensuring that it maintains its quality even after thawing.

[0015] Fourth, we hope to provide a method for manufacturing frozen donhuru that can be mass-produced with consistent quality.

[0016] means for solving problems

[0017] This invention includes pretreatment of raw materials composed of fresh fruits or fresh vegetables by washing and drying; coating the pretreated raw materials with a coating solution containing purified water, sugar and thickener; freezing the coated raw materials at -18 degrees or below to prepare Tanghu Lulu; the coating solution provides a method for preparing frozen Tanghu Lulu with a longer shelf life, characterized by mixing the thickener in a mixture of purified water and sugar heated to 100 degrees or higher.

[0018] At this point, the pretreatment of the raw materials includes a step of refrigerating at 5 degrees or lower, mixing the coating solution with purified water and sugar in a weight ratio of 1:2, and the thickener being a mixture of edible agar and edible konjac.

[0019] At this point, a coating solution is prepared by mixing purified water and sugar in a weight ratio of 1:2 and heating to 140 degrees or higher. The thickener consists of a mixture of agar and konjac. The mixture is characterized by being mixed with purified water using a mechanical stirrer.

[0020] At this point, the pretreatment of raw materials involves aging the raw materials at 5 degrees or lower; rinsing the aged raw materials with pure water; air-drying the washed raw materials at room temperature; and cutting the dried raw materials into certain sizes; the characteristic of stirring the coating solution is stirring so that no bubbles are formed when using a mechanical stirrer.

[0021] The freezing process involves first freezing the coating raw material at -18 degrees Celsius or below; vacuum-packing the newly frozen soup gourd; and then refreezing the vacuum-packed soup gourd at -5 degrees Celsius or below. The characteristic of refreezing soup gourd is that it extends the shelf life.

[0022] Invention Effects

[0023] The method for manufacturing frozen soup gourd according to the present invention has the following effects.

[0024] By subjecting raw materials to low-temperature treatment below 5 degrees Celsius and using optimized pretreatment processes, the freshness and texture of the raw materials can be maintained for a long time.

[0025] The optimal ratio of purified water and sugar, along with the use of thickeners (including agar and konjac), improves the stability of the coating layer and ensures that the coating layer remains uniform during thawing.

[0026] After vacuum packaging, the product's shelf life is extended by a first freeze at below -18 degrees Celsius and a second freeze at below -5 degrees Celsius. Even after thawing, the quality of the raw materials and coating is well maintained.

[0027] The bubble removal process using a mechanical agitator improves the uniformity of the coating, maintaining a certain level of quality even in mass production. Detailed Implementation

[0028] In the following descriptions of the specific structures or functions of the disclosed embodiments, the information is for illustrative purposes only and may be modified and performed in various forms. Therefore, the embodiments are not limited to the particular form of disclosure, and the scope of this specification includes changes, uniformities, or substitutions incorporated into the descriptive concepts.

[0029] Terms such as "first" or "second" can be used to describe various components, but the interpretation of these terms should only be used to distinguish one component from another. For example, the first component can be named the second component, and similarly, the second component can be named the first component.

[0030] When a component is said to be "connected" to another component, it should be understood that it may be directly connected to or connected to another component, but there may be another component between them.

[0031] The terminology used in the embodiments is for illustrative purposes only and should not be construed as restrictive. Singular expressions include plural expressions unless the context clearly implies otherwise. In this specification, the terms "comprising" or "having" should be understood to mean the presence of the functions, numbers, steps, actions, components, parts, or combinations thereof described herein, and should not exclude the presence or addition of one or more other functions or numbers, steps, actions, components, parts, or combinations thereof.

[0032] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary knowledge in the art to which the embodiments pertain. Terms such as those defined in common dictionaries should be interpreted as having the meaning consistent with their meaning in the relevant descriptive context and should not be interpreted in an ideal or overly formal sense unless expressly defined in this application.

[0033] This invention is intended to be practiced in many different forms and is not limited to the embodiments disclosed below, but is only intended to ensure that the disclosure of this invention is complete and to provide a complete introduction to those skilled in the art to which this invention pertains, and this invention should be defined only by the class of the claims.

[0034] In this embodiment of the invention, all terms used herein, including technical or scientific terms, unless otherwise defined, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms such as those defined in common dictionaries should be interpreted as having the meaning consistent with their meaning in the relevant descriptive context and should not be interpreted in an ideal or overly formal sense unless explicitly defined in the embodiments of the invention.

[0035] In describing this invention, detailed descriptions should be omitted if it is determined that a detailed description of relevant known technologies might unnecessarily obscure the essential points of the invention. When using terms such as "comprising," "already," and "completed" as used in this specification, additional parts may be added unless "~only" is used. This includes cases where components are expressed in the singular and include the plural, unless specifically stated otherwise.

[0036] When interpreting components, even if not explicitly stated, they will be interpreted as including the error magnitude.

[0037] Each feature in the various embodiments of the present invention can be combined with each other in part or in whole, and as those skilled in the art will fully understand, they can be technically linked and driven together, and each embodiment can be performed independently of each other or together in an associated relationship.

[0038] The present invention includes a pretreatment of raw materials consisting of fresh fruits or fresh vegetables by washing and drying; a stage of coating the pretreated raw materials with a coating solution containing purified water, sugar and a thickener; and a step of preparing Tanghuzhu by freezing the coating raw materials at -18 degrees or lower; the coating solution provides a method for preparing frozen Tanghuzhu with a longer shelf life, characterized by mixing the thickener in a solution of purified water and sugar heated to 100 degrees or higher.

[0039] At this point, the pretreatment of the raw materials includes a step of refrigerating at 5 degrees or lower, mixing the coating solution with purified water and sugar in a weight ratio of 1:2, and the thickener being a mixture of edible agar and edible konjac.

[0040] At this point, a coating solution is prepared by mixing purified water and sugar in a weight ratio of 1:2 and heating to 140 degrees or higher. The thickener consists of a mixture of agar and konjac. The mixture is characterized by being mixed with purified water using a mechanical stirrer.

[0041] At this point, the pretreatment of raw materials involves aging the raw materials at 5 degrees or lower; rinsing the aged raw materials with pure water; air-drying the washed raw materials at room temperature; and cutting the dried raw materials into certain sizes; the characteristic of stirring the coating solution is stirring so that no bubbles are formed when using a mechanical stirrer.

[0042] The freezing process involves first freezing the coating raw material at -18 degrees Celsius or below; vacuum-packing the newly frozen soup gourd; and then refreezing the vacuum-packed soup gourd at -5 degrees Celsius or below. The characteristic of refreezing soup gourd is that it extends the shelf life.

[0043] The reasons for selecting each material used in this invention and its technical significance are explained in detail below.

[0044] Reasons for choosing raw materials

[0045] In this invention, fresh fruits or vegetables are selected as raw materials. Fresh fruits and vegetables have a high water content and delicate texture, making them prone to quality deterioration during storage and processing. The method of this invention can effectively solve this problem. In particular, low-temperature treatment below 5 degrees Celsius can inhibit the enzyme activity of the raw materials and prevent the proliferation of microorganisms, thereby maintaining freshness and texture for a long time.

[0046] Reasons for choosing purified water and sugar

[0047] Pure water and sugar were chosen as the main components of the coating in a 1:2 weight ratio because the crystallization of the coating is optimized at this ratio, resulting in the best surface gloss and hardness. Pure water is free of impurities and does not interfere with sugar crystallization. When mixed with sugar and heated to above 140 degrees Celsius, it forms a supersaturated solution, which, upon cooling, forms a solid, transparent coating.

[0048] [Reasons for choosing thickeners (agar and konjac)]

[0049] In this invention, a mixture of agar and konjac is selected as the thickener. Agar exhibits gelling properties at low temperatures, which can stabilize the coating structure, while konjac has excellent water retention properties, preventing coating cracking or peeling that may occur during thawing. In particular, the use of the agar and konjac mixture synergistically expresses the advantages of each substance, providing better coating stability than using a single thickener.

[0050] Reasons for choosing vacuum packaging

[0051] Vacuum packaging is introduced into the two-stage refrigeration process to prevent the raw materials from oxidizing due to contact with oxygen, and to prevent the absorption of odors or the development of off-flavors that may occur during storage. Furthermore, vacuum packaging minimizes the movement of moisture within the product, effectively preventing potential quality degradation during thawing.

[0052] [Reason for choosing a two-stage freezing temperature]

[0053] The primary freezing temperature is set below -18 degrees Celsius to prevent the formation of large ice crystals through rapid freezing of raw materials and coatings. Secondary freezing at -5 degrees Celsius or lower ensures stable product preservation while reducing energy consumption due to excessively low temperatures. This two-stage freezing process effectively minimizes damage to the texture of raw materials during thawing and maintains the quality of the coating.

[0054] Reasons for choosing mechanical mixing

[0055] Mechanical agitators are used when preparing coating solutions to minimize the formation of air bubbles in the mixture and achieve uniform mixing. The presence of air bubbles can lead to pores in the coating, reducing quality, and uneven mixing can cause changes in the physical properties of the coating. Therefore, removing air bubbles through mechanical agitation is crucial to ensuring the uniformity of the final product quality.

[0056] All these choices of materials and process conditions work synergistically to achieve the invention’s objective: to improve the quality of the final product and extend its shelf life.

[0057] [The scope of each ingredient and the key significance of each process step]

[0058] 1. The key significance of component range

[0059] The key significance of a 1:2 weight ratio of purified water to sugar.

[0060] The 1:2 weight ratio of purified water to sugar is directly related to the physical properties of the coating. If the sugar ratio is lower than this, the coating lacks strength, resulting in stickiness during storage; if the sugar ratio is higher, the coating becomes too hard and cracks upon thawing. Therefore, a 1:2 weight ratio is the key range for optimizing the coating's strength and flexibility.

[0061] [Agar: The Key Significance of the Konjac Mixing Ratio]

[0062] When using a mixture of agar and konjac as a thickener, the appropriate mixing ratio of the two components has a decisive influence on the stability of the coating layer. If the proportion of agar is too high, the coating will become weak; if the proportion of konjac is too high, the viscosity will increase, and the processability will decrease. Therefore, the mixing ratio proposed in this invention is the optimal range that simultaneously satisfies the processability and quality of the final product.

[0063] 2. The key significance of each step in the process

[0064] [The Key Significance of the Raw Material Pre-processing Stage]

[0065] 1) Refrigerate below 5 degrees Celsius:

[0066] -Performance reasons: Inhibits enzyme activity and microbial growth in raw materials.

[0067] -Key significance: Above 5 degrees Celsius, enzyme activation accelerates quality degradation.

[0068] Importance: Determines the basic quality of the final product

[0069] 2) Washing with purified water:

[0070] - Purpose of the operation: Debris removal and surface cleaning

[0071] Key Implication: Inadequate cleaning increases the risk of microbial contamination.

[0072] -Important: Ensure the hygiene and quality of the product.

[0073] [The Key Significance of the Coating Solution Manufacturing Stage]

[0074] 1) Heating to above 140 degrees Celsius:

[0075] - Reason for doing this: The full dissolution of sugar and its bactericidal effect

[0076] Key significance: Sugar crystallizes incompletely below 140 degrees Celsius.

[0077] -Important Note: Determine the coating's transparency and durability.

[0078] 2) Mechanical stirring:

[0079] - Reason: Incomplete mixing and defoaming

[0080] -Key significance: Uneven mixing during manual stirring can lead to quality deviations.

[0081] -Important: Ensure uniformity of products

[0082] [The Key Significance of the Refrigeration Process]

[0083] 1) Initial freezing (below -18 degrees Celsius):

[0084] Reason: A rapid drop in temperature can prevent the formation of large ice crystals.

[0085] Key significance: Temperatures above -18 degrees Celsius promote mass degradation.

[0086] -Importance: Maintaining texture after thawing

[0087] 2) Vacuum packaging:

[0088] - Objective: To prevent oxidation and minimize water migration

[0089] -Key significance: Mass degradation due to oxidation in an imperfect vacuum.

[0090] -Important Note: Ensure quality for long-term preservation.

[0091] 3) Secondary freezing (below -5 degrees Celsius):

[0092] -Reason: Maintaining stable refrigeration

[0093] Key significance: When the temperature exceeds -5 degrees Celsius, the likelihood of microbial growth increases.

[0094] Importance: Maintaining quality throughout the distribution process

[0095] The key significance of full-process linkage

[0096] Each step is important, but the interconnectedness of the entire process determines the quality of the final product. In particular, when each step of pretreatment-coating-freezing is performed under the proposed conditions, the present invention achieves its objectives of maintaining raw material freshness, ensuring coating stability, and improving long-term preservation. If any step deviates from the stated conditions, the final quality may be significantly reduced, even if the other steps are performed correctly.

[0097] The conditions for each of these stages are not a simple list of numbers, but rather an optimal range confirmed through experimentation and verification, and are necessary and crucial for achieving the objectives of this invention.

[0098] [Example Analysis and Comparative Examples]

[0099] [Table 1]

[0100] Composition and process conditions of the embodiments and comparative examples

[0101]

[0102] [Table 2]

[0103] Quality evaluation results and comparative examples of the embodiments

[0104]

[0105] [Example 1]

[0106] In the most ideal embodiment of this invention, purified water and sugar are mixed in a weight ratio of 1:2, and agar and konjac are added in a ratio of 7:3. After heating at 145°C and undergoing two stages of freezing, the coating layer exhibits optimal firmness and post-thawing stability, with a retention rate as high as 90% during a 14-day shelf life.

[0107] [Examples 2 and 3]

[0108] The ratio of agar to konjac was changed to 6:4 and 8:2, respectively. Compared to Example 1, it showed slightly lower quality characteristics, but still maintained an excellent quality level.

[0109] [Comparative Example 1]

[0110] When the ratio of purified water to sugar was 1:1 and the heating temperature was reduced to 120°C, the quality deteriorated significantly during thawing due to incomplete coating formation. In particular, the shelf life was only 5 days, a result significantly lower than the example.

[0111] [Comparative Example 2]

[0112] When the sugar ratio increases and the purified water ratio decreases (0.3:1.5), the coating becomes too hard and cracks upon thawing. This demonstrates the importance of proper moisture content.

[0113] [Comparative Example 3]

[0114] When konjac is used alone as a thickener, the stability of the coating is significantly reduced, with a texture retention rate of only 50% after thawing. This demonstrates that the synergistic effect of agar and konjac has a significant impact on product quality.

[0115] [Analysis and Considerations of Experimental Results]

[0116] 1. The function of the coating solution components:

[0117] - A 1:2 sugar weight ratio of purified water has been proven to be the best choice for forming a coating.

[0118] - Agar: exhibits optimal quality characteristics at a 7:3 konjac ratio.

[0119] 2. Influence of processing conditions:

[0120] A heating temperature of -145°C is crucial for the complete dissolution of sugar and the formation of an appropriate viscosity.

[0121] Two-stage freezing (-18℃ → -5℃) is crucial for ensuring the long-term preservation of products.

[0122] 3. Correlation of quality characteristics:

[0123] - The hardness of the coating is highly correlated with its stability after thawing.

[0124] - Retention period and organizational maintenance indicate a proportional relationship

[0125] Through the above embodiments and comparative examples, it has been demonstrated that the component ratios and process conditions proposed in this invention are essential for expressing optimal quality characteristics. In particular, it has been confirmed that the content of each component and the process conditions do not act independently, but are interrelated and affect the quality of the final product.

[0126] Experimental Example

[0127] [Experimental Design and Results]

[0128] [Experimental Example 1] Evaluation of the physicochemical properties of the coating solution

[0129] 1. Viscosity Measurement

[0130] Table 3

[0131] Sample classification Viscosity (cP, 25℃) Gelation time (seconds) transparency(%) Example 1 350 45 95 Example 2 320 50 93 Example 3 380 40 94 Comparison Example 1 200 90 75 Comparison Example 2 450 30 85 Comparative Example 3 280 70 80

[0132] Measurement method:

[0133] - Viscosity: Using a Brookfield viscometer (rotor #3, 60 rpm)

[0134] - Gelation time: Gel formation time at 25℃

[0135] - Transparency: UV-Vis spectrophotometer (600nm)

[0136] [Experimental Example 2] Stability Analysis of Coating Structure

[0137] 1. DSC (Differential Scanning Calorimetry) Analysis

[0138] Table 4

[0139] Sample classification Glass transition temperature (°C) Melting point (°C) Crystallinity (%) Example 1 -35 85 65 Example 2 -33 83 63 Example 3 -36 86 64 Comparison Example 1 -28 75 45 Comparison Example 2 -40 90 55 Comparative Example 3 -30 78 50

[0140] 2. SEM (Scanning Electron Microscopy) Observation - Microstructure Analysis of Coating Cross-section - Assessment of Bubble Formation and Uniformity [Experimental Example 3] Evaluation of Storage Stability 1. Water Activity (Aw) Measurement [Table 5]

[0141] Retention period Example 1 Example 2 Example 3 Comparison Example 1 Comparison Example 2 Infancy 0.82 0.83 0.82 0.85 0.86 7 days 0.83 0.84 0.83 0.89 0.90 14 days 0.84 0.85 0.84 0.92 0.93

[0142] 2. Microbiological safety assessment

[0143] [Table 6]

[0144]

[0145] [Experimental Example 4] Evaluation of the functional properties of the coating

[0146] 1. Water retention measurement

[0147] [Table 7]

[0148] Thawing time (hours) Example 1 Example 2 Example 3 Comparison Example 1 1 98％ 96％ 97％ 85％ 2 95％ 93％ 94％ 75％ 4 92％ 90％ 91％ 65％

[0149] 2. Mechanical strength measurement

[0150] - Using a texture analyzer

[0151] - Hardness, elasticity, and cohesion measurement

[0152] [Additional experimental examples of specific implementation of the present invention]

[0153] [Example 5] Molecular weight and molecular structure analysis

[0154] This experiment aims to study the molecular weight distribution of agar and konjac, as well as the mechanism of coating layer formation.

[0155] 1. Molecular weight analysis

[0156] The molecular weight of the sample was analyzed using gel permeation chromatography (GPC). The analytical conditions were as follows: - Column: Aquatic ultrahydrogel 2000

[0157] -Mobile phase: 0.1M NaNO3 aqueous solution

[0158] - Flow rate: 0.8 ml / min

[0159] Temperature: 40℃

[0160] - Detector: Differential refractive index detector

[0161] [Table 8]

[0162]

[0163] [Experimental Example 6] Evaluation of Thermal Stability

[0164] This experiment was conducted to evaluate the thermal stability of the manufactured candied hawthorn skewers.

[0165] 1. Thermogravimetric analysis

[0166] -Instrument: TA Instruments TGA Q500

[0167] - Temperature rise: 10℃

[0168] -Temperature range: -50℃~200℃

[0169] -Atmosphere: Nitrogen

[0170] [Table 9]

[0171]

[0172] [Experimental Example 7] Surface Characterization

[0173] 1. Contact angle measurement

[0174] - Instrument: Phoenix 300 Contact Angle Thickness Gauge - Measurement Temperature: 25℃

[0175] Solution: Distilled water

[0176] [Table 10]

[0177] Sample classification Contact angle (°) Surface energy (mN / m) Example 1 65 42.5 Example 2 67 41.8 Comparison Example 1 45 55.3

[0178] 2. AFM Analysis

[0179] - Device: Brook size icon

[0180] - Scan range: 10μm × 10μm

[0181] -Mode: Click mode [Example 8] Rheological characterization

[0182] 1. Dynamic point elasticity measurement

[0183] -Instrument: TA Instruments ARES-G2

[0184] - Frequency: 0.1-100 rad / s

[0185] Temperature: 25℃

[0186] [Table 11]

[0187] Frequency (rad / s) Energy storage modulus (G', Pa) Loss modulus (G, Pa) 0.1 1000 100 1.0 2000 150 10 5000 200 100 8000 300

[0188] [Example 9] FTIR spectrum

[0189] 1. Intermolecular interaction analysis

[0190] -Instrument: Thermo Fisher Scientific iS50

[0191] - Measuring range: 4000-400cm-1

[0192] - Resolution: 4cm-1

[0193] -Number of scans: 32

[0194] [Table 12]

[0195] Peak position (cm⁻¹) Function Intensity change (after 14 days of storage) 3400 OH Reduce by 5% 1650 C=O Reduce by 3% 1150 CO No change

[0196] [Summary of Experimental Results]

[0197] The following conclusions can be drawn from the above additional experiments:

[0198] 1. Molecular structural properties:

[0199] - The optimal molecular weight distribution of agar and konjac contributes to the stability of the coating layer.

[0200] - A uniform molecular weight distribution is required, with a dispersion of less than 1.3.

[0201] 2. Thermal stability:

[0202] - Weight loss remains below 2% within a temperature range of -20°C to 40°C.

[0203] -Proven excellent cold insulation stability

[0204] 3. Surface characteristics:

[0205] Maintain an appropriate contact angle (65-70°) to ensure coating stability.

[0206] -Nanoscale uniform surface roughness

[0207] 4. Rheological properties:

[0208] - Exhibits stable viscoelasticity over a wide frequency range

[0209] - The energy storage modulus is higher than the loss modulus, therefore the structure has excellent stability.

[0210] 5. Intermolecular interactions:

[0211] - Stable maintenance of hydrogen bonds during storage

[0212] -Minimum chemical structural change

[0213] The above additional experimental results scientifically demonstrate the superiority of the present invention, especially the clearly determined molecular-level stability and structural properties.

[0214] [Results and Discussion]

[0215] The results of various experiments conducted in this invention were comprehensively analyzed, and the following conclusions were drawn.

[0216] 1. Physicochemical properties of the coating liquid

[0217] The viscosity of the coating solution has been identified as a key factor determining product quality. Example 1, 350 cP, proved to be the optimal viscosity, providing sufficient thickness and uniformity in coating formation. Of particular note is the gelation time; in Example 1, 45 seconds proved to be ideal. Shorter gelation times (Comparative Example 2, 30 seconds) reduced workability, while longer gelation times (Comparative Example 1, 90 seconds) resulted in uneven coatings.

[0218] 2. Molecular structural properties

[0219] GPC analysis confirmed that the molecular weight distribution of agar and konjac is directly related to the physical properties of the coating. The optimal combination of an agar average molecular weight of 120,000 and konjac average molecular weight of 180,000, with a dispersion maintained below 1.3, resulted in a uniform coating layer. Of particular note is the complementary molecular weight distribution of the two components, producing a synergistic effect.

[0220] 3. Thermal stability and structural stability

[0221] As a result of DSC analysis, the glass transition temperature of Example 1 was confirmed to be -35°C, which was determined to be the optimal temperature for ensuring structural stability during refrigeration. In TGA analysis, the weight loss remained below 1.5% within a temperature range of -20°C to 40°C, demonstrating excellent thermal stability. In particular, the microstructure identified by SEM observation showed a uniform pore distribution and a dense structure.

[0222] 4. Surface properties and physical stability

[0223] As a result of contact angle measurements, the 65° contact angle of Example 1 demonstrates a suitable balance between surface hydrophilicity and hydrophobicity, which is directly related to the stability of the coating. Nanoscale surface roughness confirmed by AFM analysis confirms the formation of a uniform coating. Of particular note is the surface energy maintained at 42.5 mN / m, indicating optimal coating conditions.

[0224] 5. Rheological properties

[0225] The results of dynamic viscoelasticity measurements most clearly demonstrate the superiority of the present invention. The fact that the storage modulus (G') is significantly higher than the loss modulus (G') proves the structural stability of the product. In particular, the stable change in modulus due to frequency variation is directly related to the long-term storage of the product.

[0226] 6. Intermolecular interactions and chemical stability

[0227] The intermolecular interactions identified by FTIR analysis revealed very interesting results. A slight decrease (5%) in OH bonds (3400 cm⁻¹) means that the chemical structure remains stable even after 14 days of storage. A 3% decrease (1650 cm⁻¹) in C=O bonds is acceptable, and the lack of change in CO bonds (1150 cm⁻¹) indicates structural stability.

[0228] 7. Preservation stability and microbial safety

[0229] As measured by water activity (Aw), it remained below 14 during a storage period of 0.84 days, confirming effective inhibition of microbial growth. In particular, the fact that the general bacterial count remained below 100 CFU / g demonstrates the excellent preservation properties of this invention. In water retention measurements, it showed a high water retention capacity of 92% even 4 hours after thawing, confirming its excellent effect on maintaining product quality.

[0230] In summary, the embodiments of the present invention demonstrated superior performance compared to the comparative examples in all analytical tests. In particular, molecular-level structural stability, optimization of physicochemical properties, and microbiological safety were considered to contribute to improved quality of the final product. These results scientifically demonstrate that the component ratios and process conditions proposed in this invention are the optimal combination.

Claims

1. A method for preparing frozen candied hawthorn skewers with a longer shelf life, characterized in that, The method includes: pre-treating raw materials composed of fresh fruits or fresh vegetables by washing and drying; coating the pre-treated raw materials with a coating solution containing purified water, sugar and thickener; freezing the coating raw materials at -18 degrees or below to prepare Tanghu Lulu; the coating solution is prepared by mixing a thickener with a mixture of purified water and sugar in a solution heated to above 100 degrees.

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