Fresh corn food and preparation method thereof

Abstract

The invention provides a fresh corn food and a preparation method thereof, and belongs to the technical field of food processing. The preparation method of the fresh corn food provided by the invention comprises the following steps: sequentially carrying out a pretreatment process, an enzyme deactivation process and a post-treatment process on a to-be-processed material to prepare the fresh corn food, wherein the enzyme deactivation process comprises the following steps: covering a flexible protection piece on a material to be subjected to enzyme deactivation, and then performing microwave enzyme deactivation in a microwave environment. Through the preparation method provided by the invention, the enzyme deactivation effect of the fresh corn food can be effectively improved, and meanwhile, rich nutrient substances of the fresh corn food are reserved, so that the quality of the fresh corn food is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to a fresh corn food and a preparation method thereof. Background Art

[0002] Fresh corn refers to corn cobs or corn kernels harvested during the milky stage, also known as fresh corn. Fresh corn kernels produce more sugar, starch, crude fat, and a variety of vitamins and amino acids during the milky stage. Compared with dry corn and old corn, fresh corn has better taste and nutritional value, and is more convenient to eat. It usually only needs to be boiled or steamed before eating.

[0003] Traditional fresh corn foods usually include quick-frozen corn cobs, vacuum-packed corn cobs and quick-frozen corn kernels. During the preparation of these fresh corn foods, the enzymes inside the raw materials remain active after harvesting. Under suitable temperature and conditions, these enzymes will accelerate the physiological metabolism of corn, resulting in loss of nutrients and degradation of quality. Therefore, it is usually necessary to inactivate the enzymes in the processed raw materials.

[0004] In traditional technology, hot water blanching is often used to inactivate enzymes in the hope of inhibiting or destroying the activity of these enzymes, thereby slowing down or preventing the occurrence of the above-mentioned adverse changes.

[0005] However, in the prior art, 95°C hot water is generally used for blanching. When a whole ear of corn is blanched in hot water, heat is transferred from the water with higher temperature to the corn kernels with lower temperature, and then from the corn kernels to the corn cobs. Since the diameter of the corn cobs is larger and the structure is relatively tight, the speed at which heat is transferred from the corn kernels to the corn cobs is slower. As a result, even after the corn kernels of the whole ear of corn are fully inactivated, more enzymes such as catalase are still present in the corn cobs, resulting in poor enzyme inactivation effect of fresh corn food and serious quality degradation after long-term storage.

[0006] In addition, corn comes into direct contact with high-temperature water during blanching, causing the water-soluble nutrients and pigments rich in corn to dissolve in the high-temperature water and be seriously lost (for example, the loss rate of soluble sugar content is about 38%, and the loss rate of VC is about 50%). Especially for nutrients such as anthocyanins in colored corn and black corn, the loss rate is particularly serious, resulting in low nutritional value and poor quality of fresh corn food. Summary of the invention

[0007] Technical problems solved by the present invention:

[0008] In the prior art, in the process of preparing fresh corn food, hot water blanching is used for enzyme inactivation. The enzyme inactivation of the corn cob of the whole ear of corn is incomplete, resulting in poor enzyme inactivation effect of the fresh corn food. In addition, the corn is in direct contact with high-temperature water during blanching, which causes serious loss of nutrients and pigment substances rich in the corn. Therefore, there is still a need for a method for preparing fresh corn food with good enzyme inactivation effect, high nutritional value and excellent quality.

[0009] In response to at least part of the above-mentioned defects, the present invention provides a fresh corn food and a preparation method thereof, which can achieve overall and comprehensive enzyme inactivation of the whole ear of corn and change the process defect that corn needs to be directly contacted with high-temperature water for blanching, thereby overcoming the problems of poor enzyme inactivation effect, serious loss of nutrients and poor quality of fresh corn food.

[0010] The technical solution of the present invention is as follows:

[0011] 1. A method for preparing fresh corn food, comprising sequentially performing a pre-treatment process, an enzyme inactivation process and a post-treatment process on a material to be processed to obtain the fresh corn food;

[0012] The enzyme inactivation process includes covering the material to be inactivated with a flexible protective piece and then performing microwave inactivation in a microwave environment.

[0013] 2. In the method for preparing fresh corn food of item 1, the enzyme inactivation step specifically comprises:

[0014] The material to be inactivated is covered with a flexible protective member and then transported under a microwave environment for a first predetermined microwave inactivation time; optionally, the first predetermined time is 1 to 10 minutes, preferably 4 to 10 minutes.

[0015] 3. In the preparation method of fresh corn food as described in item 2 or 3, the enzyme inactivation step further comprises: stopping the microwave treatment of the material to be inactivated by microwave and keeping it warm for a second predetermined time; preferably, the second predetermined time is 0.1 to 10 minutes.

[0016] 4. In the method for preparing fresh corn food according to any one of items 1 to 3, the flexible protective member comprises at least one of Teflon high-temperature cloth, silicone cloth or polyester film.

[0017] 5. In the preparation method of fresh corn food as described in any one of items 1 to 4, when the fresh corn food is quick-frozen corn cobs or vacuum-packed corn cobs, the pre-treatment process includes bubbling cleaning operation and high-pressure cleaning operation; optionally, in the bubbling cleaning operation, water immersion bubbling flushing is adopted; optionally, in the high-pressure cleaning operation, rollers are used to transport the material after the bubbling cleaning operation so that the material is cleaned by high-pressure water during the tumbling process.

[0018] 6. In the preparation method of fresh corn food as described in any one of items 1 to 5, when the fresh corn food is quick-frozen corn cobs or vacuum-packed corn cobs, the post-processing step includes a first cooling operation; optionally, in the first cooling operation, the material after the enzyme inactivation step is immersed in cooling water for cooling, the cooling water temperature is 4°C to 30°C, and the cooling time is 2 to 8 minutes.

[0019] 7. In the preparation method of fresh corn food of any one of items 1 to 6, when the fresh corn food is vacuum-packed corn cobs, the post-processing process also includes vacuum packaging operation, sterilization operation and foreign matter detection operation; optionally, the sterilization temperature is 110℃~130℃, the sterilization time is 18~30min, and the pressure range during the sterilization process is 0.1Mpa~0.3Mpa; or when the fresh corn food is quick-frozen corn cobs, the first draining operation also includes a first quick-freezing operation and a foreign matter detection operation; optionally, in the first quick-freezing operation, the quick-freezing temperature is below -30℃, and the material is quick-frozen to a center temperature of less than -18℃.

[0020] 8. In the preparation method of fresh corn food as described in any one of items 1 to 7, when the fresh corn food is quick-frozen corn kernels, the pre-treatment steps include air separation and impurity removal operation, rotary screening operation and rotary water washing operation; optionally, in the air separation and impurity removal operation, the material is lifted to a preset height and then dropped, and wind is blown to assist in the falling process of the material; optionally, in the rotary screening operation, the material after the air separation and impurity removal operation is placed in a rolling screen for rotary screening; optionally, the rotary water washing operation includes immersing the material after the rotary screening operation in water, rotary washing under water flow disturbance, and placing the material after the rotary water washing on a screen for spray washing.

[0021] 9. In the preparation method of fresh corn food as described in any one of items 1 to 8, when the fresh corn food is quick-frozen corn kernels, the post-processing steps include a second cooling operation, a spreading operation, a second quick-freezing operation, a selecting operation, a quantitative packaging operation and a foreign matter detection operation; optionally, in the second cooling operation, normal temperature water and cold water are used in turn to cool the material after the enzyme inactivation step, and the cold water temperature is 4 to 15°C; optionally, in the spreading operation, the material is spread under vibration conditions, and the thickness of the spread is less than 4 cm; optionally, the selecting operation includes color sorting and / or screening and grading of the material after the second quick-freezing operation.

[0022] 10. In the method for preparing fresh corn food according to any one of items 1 to 9, in the second quick-freezing operation, the quick-freezing temperature is below -30°C, and the material is quick-frozen until the center temperature is less than -18°C; optionally, the second quick-freezing operation freezes the material in a quick-freezing tunnel or quick-freezing warehouse.

[0023] 11. A fresh corn food, prepared by the method of any one of items 1 to 10.

[0024] The present invention has at least the following beneficial effects:

[0025] By adopting the preparation method of the present invention to prepare fresh corn food, direct contact between the fresh corn food and high-temperature water during the enzyme inactivation process can be avoided, so as to effectively reduce the loss of water-soluble nutrients, especially for colored corn and black corn rich in nutrients such as anthocyanins, the nutrients are better retained; after the material to be inactivated is covered with a flexible protective piece, microwave enzyme inactivation is carried out in a microwave environment, so that the material to be inactivated is relatively isolated from the external environment under the cover of the flexible protective piece.

[0026] Under the action of microwaves, the evaporated water produced by the material to be inactivated is retained around the material to be inactivated, so as to increase the humidity of the inactivation environment of the material to be inactivated, and different parts of the material to be inactivated are heated more evenly, thereby avoiding local overheating of the material to be inactivated and the generation of sticky spots, which significantly improves the quality of fresh corn food. Moreover, since microwave heating is selective, microwaves can focus on heating the corncob with high water content, making the corncob inactivation more thorough, which is conducive to significantly improving the overall inactivation effect of fresh corn food, thereby increasing the shelf life of fresh corn food and ensuring that it still maintains good quality after long-term storage.

[0027] Therefore, according to the method of the present invention, fresh corn is selectively heated to inactivate enzymes using microwave enzyme inactivation technology, which effectively improves the enzyme inactivation effect while retaining rich nutrients, significantly improving the quality of fresh corn food, and has broader application prospects and commercial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A photo of peroxidase activity detection of the fresh corn food prepared in Example 1 of the present invention is shown;

[0030] Figure 2 A photo of peroxidase activity detection of the fresh corn food prepared in Comparative Example 2 of the present invention is shown;

[0031] Figure 3 A photo of the material after the enzyme inactivation step and the blanching water in Comparative Example 3 of the present invention is shown;

[0032] Figure 4A photograph showing the material cooled by normal temperature water during the second cooling operation in Example 4 of the present invention;

[0033] Figure 5 A photo of the fresh corn food prepared in Comparative Example 4 of the present invention is shown;

[0034] Figure 6 A schematic diagram of the structure of a conveying mechanism exemplarily provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] It should be understood that the specific embodiments given herein are for the purpose of explaining to those skilled in the art and are merely illustrative rather than restrictive.

[0036] In the following description, many specific details are set forth to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that specific details need not be adopted to practice the present invention. In other cases, well-known steps or operations are not described in detail to avoid obscuring the present invention.

[0037] It should be noted that in this article, the meanings of relevant terms are as follows:

[0038] The term "microwave environment" refers to an environment composed of electromagnetic waves. Electromagnetic waves have the characteristics of alternating electric and magnetic fields. When a material is in this external alternating electromagnetic field, the polar molecules in the material will become polarized and change their orientations as the polarity of the external electromagnetic field changes. Due to frequent friction losses between numerous polar molecules, electromagnetic energy is converted into heat energy.

[0039] The term "Teflon high temperature cloth" refers to a fiber cloth made of polytetrafluoroethylene emulsion impregnated with high-performance glass fiber cloth.

[0040] The term "silicone cloth" refers to a material made of silicone coated or compounded on a base material such as cloth or fiber.

[0041] The term "polyester film" refers to a plastic film made of polyester resin, the main raw material of which is polyethylene terephthalate (PET).

[0042] The term "water immersion bubbling flushing" refers to using water as a medium and introducing gas into the water by bubbling, thereby utilizing the stirring and flushing effects of the bubbles to clean or flush the target object or surface.

[0043] The term "roller conveying" refers to a method of conveying materials by rolling; exemplarily, such roller conveying is achieved by a device consisting of a roller and a power system, and the roller is driven to rotate by an electric motor to convey the material from one place to another in a rolling manner.

[0044] The term "blanching" is also called blanching, which refers to the method of heat treatment of plant foods with hot water or steam to inactivate the enzymes in the plant foods themselves, thereby preventing the food from spoiling.

[0045] The term "black corn" refers to corn with varying degrees of melanin deposited in the cuticle of the grain, giving it a shiny black appearance. It is rich in anthocyanins, water-soluble melanin and various other trace elements essential to the human body, plant protein and various amino acids, and has a high nutritional content.

[0046] The term "sweet corn" is also called fruit corn. The kernels are plump, juicy, delicious and sweet, which contain more sugar in the milky stage. The content of protein, fat, lysine and tryptophan in the milky and tender kernels is richer than that of ordinary corn.

[0047] The term "white corn" refers to a corn variety whose kernels are mainly white or light yellow in color. It is rich in carbohydrates, protein, fat, vitamins and minerals, and is often used to make corn products such as cornmeal, corn flakes, corn starch, etc.

[0048] The term "colored corn" refers to corn kernels with colorful colors, including purple, black, red, and flowery colors. Colored corn is obtained by cross-pollination and hybridization of corn varieties of different colors. It has richer nutrients than ordinary corn.

[0049] The term "anthocyanidin", also known as anthocyanin or anthocyanin pigment, is a class of water-soluble natural pigments widely found in plants. Anthocyanidins are glycoside derivatives that are easily soluble in polar solvents such as water, methanol, and ethanol. They have strong antioxidant and inflammatory response inhibitory abilities, which can help protect cells from oxidative damage, relieve symptoms of inflammatory diseases, protect cardiovascular health, regulate blood sugar, and improve vision.

[0050] The present invention will be described in detail below.

[0051] The embodiment of the present invention provides a method for preparing fresh corn food, comprising sequentially performing a pre-treatment process, an enzyme inactivation process and a post-treatment process on a material to be processed to prepare the fresh corn food;

[0052] The enzyme inactivation process includes covering the material to be inactivated with a flexible protective piece and then performing microwave inactivation in a microwave environment.

[0053] According to the preparation method of fresh corn food provided by the embodiment of the present invention, the material to be processed is first subjected to a pre-treatment process. In the pre-treatment process, the inedible parts of the material to be processed and excess impurities can be removed to improve the overall quality of the fresh corn food. Then, the material to be inactivated obtained after the pre-treatment process is subjected to an enzyme inactivation process. During the enzyme inactivation process, the material to be inactivated is covered with a flexible protective member and then subjected to microwave enzyme inactivation in a microwave environment. The microwave can penetrate the flexible protective member and directly act on the inside and surface of the material to be inactivated, and the flexible protective member can retain the evaporated water generated by the material to be inactivated around the material to be inactivated to increase the humidity of the enzyme inactivation environment of the material to be inactivated. Different parts of the material to be inactivated are heated more evenly, thereby avoiding local overheating of the material to be inactivated and the generation of sticky spots, so that the quality of the fresh corn food is significantly improved. Moreover, microwave heating is selective. When the whole ear of corn is subjected to microwave enzyme inactivation, the corn cob is It has a higher water content (the water content of the corn cob of a whole ear of corn is generally about 80%), and has a stronger ability to absorb microwaves. Microwaves can focus on heating the corn cob, making the corn cob enzyme-killing more thorough, which is beneficial to significantly improve the overall enzyme-killing effect of fresh corn food. At the same time, since the material to be inactivated is inactivated by microwaves, it does not need to be in direct contact with high-temperature water, which effectively reduces the loss of water-soluble nutrients such as anthocyanins, soluble sugars and VC in the fresh corn food, so that the nutritional components of the fresh corn food are fully retained. The material obtained after the enzyme-killing process is further subjected to a post-processing process to obtain a fresh corn food with rich nutrient retention, thorough enzyme killing and excellent quality.

[0054] It should be noted that, in the embodiment of the present invention, after the material to be inactivated is covered with a flexible protective member and then subjected to microwave inactivation in a microwave environment, the key purpose of the design of the flexible protective member is to fully isolate the material to be inactivated from the external environment, prevent the loss of heat along with the moisture generated by the material to be inactivated when heated, ensure that the material to be inactivated is heated evenly during the inactivation process, and reduce energy consumption; therefore, under the condition of meeting the above purposes, when covering the material to be inactivated, the flexible protective member can cover and shield the exposed surface of the entire material to be inactivated, that is, completely wrap the surface of the material to be inactivated to form a relatively closed enzyme inactivation environment; or the flexible protective member can cover at least one side of the material to be inactivated, and cooperate with the mechanism that supports the material to be inactivated to form a relatively closed enzyme inactivation environment, so as to facilitate the moisture generated by the material to be inactivated when heated to be retained around the material to be inactivated.

[0055] Furthermore, the fresh corn food prepared by the preparation method in the embodiment of the present invention can be quick-frozen corn cobs, vacuum-packed corn cobs, quick-frozen corn kernels and other products made from fresh corn as raw materials; when facing different target products, the pre-treatment process and post-treatment process in the preparation method of this embodiment can be adaptively adjusted.

[0056] For example, when the target product is a whole ear of corn such as vacuum-packed corn cobs, the head and tail parts of the whole ear of corn can be cut off in the pre-treatment process, and the whole ear of corn after the head and tail parts are cut off can be cleaned and impurities removed before the enzyme inactivation process; when the target product is quick-frozen corn kernels, the whole ear of corn can be threshed in the pre-treatment process, the corn cobs can be removed, and the whole ear of corn can be cleaned and impurities removed before the enzyme inactivation process.

[0057] Therefore, the material to be inactivated in the embodiment of the present invention can be a whole ear of corn (i.e., corn cobs) or corn kernels; the whole ear of corn or corn kernels are covered with a flexible protective member and then inactivated by microwaves in a microwave environment, without the need to come into contact with running water at a higher temperature, so as to avoid the loss of water-soluble nutrients such as pigments and soluble sugars; especially when the material to be inactivated is a whole ear of corn, the preparation method of this embodiment can further inactivate the peroxidase in the corn cob, so as to increase the shelf life of the fresh corn food and ensure that it maintains good quality after long-term storage.

[0058] To facilitate industrial continuous production, in some optional embodiments, the enzyme inactivation process specifically includes: covering the material to be inactivated with a flexible protective member and then conveying it in a microwave environment, and inactivating the enzyme by microwave for a first predetermined time. By covering the material to be inactivated with a flexible protective member and then conveying it in a microwave environment, and inactivating the enzyme by microwave for a first predetermined time, the material to be inactivated generates heat and evaporates water in the microwave environment, and the flexible protective member can inhibit the loss of evaporated water generated by the material to be inactivated, and increase the environmental humidity around the material to be inactivated, so that the material to be inactivated is heated more evenly, while reducing the loss of heat and water, and ensuring that the enzyme inactivation of fresh corn food is more complete.

[0059] In the embodiment of the present invention, the material to be inactivated is covered with a flexible protective member and then transported under a microwave environment. This can be achieved by using a conveying mechanism A equipped with a microwave generator d (for example, a microwave processing device designed with a conveyor belt). The conveying mechanism has one or more microwave generators d to form a microwave environment required for the enzyme inactivation process. After the flexible protective member covers the material to be inactivated on the conveying mechanism A, it can form a relatively closed enzyme inactivation environment with the conveying mechanism A. The enzyme inactivation process is performed by using the conveying mechanism A equipped with a microwave generator d, which can meet the continuous production requirements of the preparation method provided in the embodiment of the present invention during industrial application.

[0060] To avoid ambiguity among those skilled in the art, reference is made to Figure 6 As shown, the embodiment of the present invention exemplarily provides a conveying mechanism A suitable for the enzyme inactivation process, and the conveying mechanism A includes a feeding system a, a transmission belt b, a microwave suppression system c, a microwave generator d, a microwave action cavity e, a dehumidification system f and a feeding system g; wherein one or more microwave generators d (such as Figure 6The microwave generator d is capable of generating a microwave environment in the microwave action cavity e to perform microwave enzyme inactivation on the material to be inactivated. The design of multiple microwave generators d is beneficial to reducing the time of the enzyme inactivation process and improving the processing volume and processing efficiency of the material to be inactivated. The microwave suppression system c is arranged outside the microwave action cavity e to block microwaves, prevent and control microwave leakage, and ensure the safe operation of the equipment. The dehumidification system f is connected to the microwave action cavity e to discharge the moisture in the microwave action cavity e. The conveyor belt b can be designed as one or multiple (such as Figure 6 The three conveyor belts b shown in the figure are arranged between the loading system a and the unloading system g. The middle section of the conveyor belt b passes through the microwave action cavity e to receive the material to be inactivated conveyed by the loading system a, and transport the material to be inactivated into the microwave action cavity e under the covering flexible protective part for microwave inactivation, and transport it out of the microwave action cavity e for heat preservation, and transport the material after the enzyme inactivation process to the unloading system g for processing in subsequent processes.

[0061] It should be noted that the conveying mechanism A can use a water cooling system (not shown) to dissipate heat to maintain a constant temperature of the equipment. The application environment temperature of the conveying mechanism A should be greater than 0°C and less than 40°C. An application environment temperature below 0°C may easily cause the cooling water in the water cooling system to freeze, thereby affecting the heat dissipation efficiency. An application environment temperature above 40°C may easily lead to poor heat dissipation of equipment-related components, affecting the service life of the equipment.

[0062] In some optional embodiments of the present invention, the first predetermined time can be selected as 1 to 10 minutes, preferably 4 to 10 minutes; for example, the first predetermined time can be 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes, 6 minutes, 6.5 minutes, 7 minutes, 7.5 minutes, 8 minutes, 8.5 minutes, 9 minutes, 9.5 minutes, 10 minutes or a time range limited by any two of them; when the first predetermined time is less than 1 minute, the microwave enzyme inactivation time is short, which will lead to incomplete enzyme inactivation of fresh corn food and poor product quality, while the first predetermined time is greater than 10 minutes, the microwave enzyme inactivation time is too long, resulting in a significant reduction in production efficiency and high energy consumption; by using the first predetermined time within the above time range of microwave enzyme inactivation, the fresh corn food can be fully enzyme-inactivated while the energy utilization rate is higher, the pigment and nutritional components of the fresh corn food can be better retained, and the quality is better; according to the different processing amounts of the material to be inactivated, the first predetermined time for microwave enzyme inactivation can be adaptively selected within the above range.

[0063] In some optional embodiments, the enzyme inactivation process further includes: stopping the microwave treatment of the material to be inactivated by microwave and keeping it warm for a second predetermined time; stopping the microwave treatment of the material to be inactivated by microwave and keeping it warm, at which time the material to be inactivated by microwave is still covered with a flexible protective piece, so that the heat in the enzyme inactivation environment can be fully preserved, and during the insulation process, the temperature of different parts of the material can be further balanced under a high humidity environment to ensure that all parts of the fresh corn food can achieve sufficient enzyme inactivation. In addition, the insulation design effectively reduces the time of microwave supply, helps save energy and improve the safety of the production environment, and can further reduce the loss of nutrients in the fresh corn food.

[0064] In some optional embodiments, the second predetermined time is 0.1 to 10 minutes; for example, the second predetermined time can be 0.1 minutes, 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes, 6 minutes, 6.5 minutes, 7 minutes, 7.5 minutes, 8 minutes, 8.5 minutes, 9 minutes, 9.5 minutes, 10 minutes or a time range limited by any two of them; keeping warm within the above appropriate second predetermined time range is beneficial to balancing the temperature difference of different parts of the material after microwave enzyme inactivation, ensuring that the temperature of the corn after microwave enzyme inactivation is uniform, so that the moisture and nutrients in the corn are better retained, while the enzymes in various parts of the fresh corn food are fully inactivated, ensuring that it still maintains good quality after long-term storage.

[0065] In some optional embodiments, the flexible protective member includes at least one of Teflon high temperature cloth, silicone cloth or polyester film. The above materials as flexible protective members have the characteristics of high flexibility, high temperature resistance, waterproof and non-toxicity. In the enzyme inactivation process, they are covered on the surface of the material to be inactivated, can adapt to the shape of the material to be inactivated, and fit closely with the material to be inactivated, so that the moisture and heat generated by the material to be inactivated after microwave action are effectively retained, and the temperature of different parts of the material to be inactivated in the enzyme inactivation process is more balanced, so that the enzyme of the fresh corn food is fully inactivated while having rich nutritional value and excellent quality.

[0066] In view of the different types of fresh corn food, in some optional embodiments, when the fresh corn food is a vacuum-packed corn cob, the pre-treatment steps include acceptance operation, skinning and silk removal operation, head and tail cutting operation, bubbling cleaning operation and high-pressure cleaning operation.

[0067] It can be understood that when the fresh corn food is quick-frozen corn cobs or vacuum-packed corn cobs, the materials are all corn cobs during the entire preparation process. In the pre-treatment process, the materials to be processed are inspected and accepted according to the preset acceptance standards for the fullness of the grains, the size of the cobs, the color, the variety, the maturity and the presence of foreign matter in the whole ear of corn, so as to ensure that the fresh corn food has better quality. The materials after the acceptance are then peeled and desilked to remove larger debris such as the corn husk and filaments, so as to reduce the subsequent impurity removal costs. The materials after the peeling and desilking operations are then cut and tailed, and corn that does not meet the requirements in terms of color, cob shape, size and tenderness can be removed during the cutting and tailing operations. The rice cobs are further removed, and the heads and tails of the whole ears of corn with good morphological quality are cut off after selection, so that the size specifications of the corn cobs in the subsequent preparation process can be closer, which is convenient for unified processing and is conducive to improving the product consistency of fresh corn food; the material obtained after the head and tail cutting operation is further subjected to a bubbling cleaning operation, which can make the material surface cleaner and remove impurities that are easy to detach, such as corn silk and possible stems and leaves; the material obtained after the bubbling cleaning operation is subjected to a high-pressure cleaning operation, which can fully remove impurities in the material that are difficult to remove (such as foreign matter remaining in the gaps between corn kernels) to obtain a cleaner material, so that the fresh corn food has a better quality.

[0068] In view of the different types of fresh corn food, in some optional embodiments, when the fresh corn food is a quick-frozen corn cob, the pre-treatment process includes acceptance operation, peeling and de-filamenting operation, bubbling cleaning operation and high-pressure cleaning operation in sequence. It is understandable that in the process of preparing the fresh corn food as quick-frozen corn cobs, the quick-frozen corn cobs are peeled and de-filamented without cutting the head and tail, which can prevent the corn cobs from falling off during subsequent storage and reprocessing, thereby improving product quality and avoiding material waste.

[0069] It should be noted that the husking and silk removal operations in the embodiment of the present invention can be implemented by a conventional corn husking machine, and the cutting off of the head and tail of the whole ear of corn can be implemented by a conventional head and tail cutting equipment.

[0070] The bubbling cleaning operation in the embodiment of the present invention is a cleaning method that uses compressed air to make water surge, so that impurities on the surface of the material are quickly separated. In some preferred embodiments of the present invention, in the bubbling cleaning operation, water immersion bubbling flushing is adopted; during the water immersion bubbling flushing process, the material is immersed in normal temperature water, and bubbles are formed in the water by continuously supplying water vapor at the bottom of the normal temperature water. The bubbles float up to form disturbances to clean the surface of the material, so that foreign objects such as corn silk or leaves that are easy to separate in the material float on the water surface, and these foreign objects can be further removed by the circulating filtration system. If the cleaning time of the water immersion bubbling flushing is too short, the dirt and impurities on the surface of the material may not be completely cleaned; if the cleaning time is too long, it may cause unnecessary damage to the material, such as nutrient loss, poor taste, etc. Therefore, the time of the water immersion bubbling flushing is controlled within the range of 2 to 8 minutes, within which the cleaning effect can be ensured, while avoiding unnecessary damage to the material caused by excessive cleaning time.

[0071] For corn cobs, corn kernels are usually tightly arranged on the surface of the corn cob. Foreign matter in the gaps between the corn kernels needs to be washed with high-pressure water. In the high-pressure cleaning operation, rollers are used to convey the material after the bubbling cleaning operation, so that the material is cleaned by high-pressure water during the tumbling process; roller conveying can realize the tumbling of the material during the conveying process, so that the material can be washed by high-pressure water at 360°, and the high-pressure water can be separated from the material in time, so that foreign matter is not easy to remain. The water carrying foreign matter is circulated and filtered and then recycled by a high-pressure pump to reduce the water resource consumption in the high-pressure cleaning operation, increase the uniformity and efficiency of cleaning, and more effectively remove stubborn dirt on the surface of the material.

[0072] The high-pressure cleaning operation combines high-pressure water flow and roller conveying, so that the material to be cleaned is flushed with high-pressure water during the tumbling process. To ensure that the dirt and impurities on the surface of the material are effectively removed and to avoid unnecessary damage to the material due to excessive cleaning time, the time of the high-pressure cleaning operation is appropriately controlled within the range of 2 to 8 minutes.

[0073] Furthermore, when the fresh corn food is quick-frozen corn cobs or vacuum-packed corn cobs, in some optional embodiments, the post-processing steps sequentially include a first cooling operation and a first draining operation.

[0074] It can be understood that the corn cob material after the enzyme inactivation process has a relatively high temperature (about 90-98°C, and the temperature distribution of various parts of the corn cob material is uniform). By performing the first cooling operation on the material after the enzyme inactivation process, the corn cob can be cooled in time to prevent further loss of nutrients in the material and the growth of microorganisms, and slow down the quality degradation during subsequent quick freezing or vacuum packaging; further performing the first draining operation on the material after the first cooling operation can fully remove the cooling water on the surface of the material after the first cooling operation, so as to facilitate quick freezing or vacuum packaging in the subsequent process.

[0075] In some optional embodiments, in the first cooling operation, the material after the enzyme inactivation process is immersed in cooling water for cooling, and the cooling water temperature is 4°C to 30°C. Cooling with cooling water at a temperature of 4°C to 30°C can prevent the quality of the material after the enzyme inactivation process from being in a high temperature state for a long time and causing microbial reproduction, and to a certain extent, the corn kernels in the material restore a certain moisture content to maintain its taste and nutritional value. In terms of time control of the first cooling operation, if the cooling time is too short, the material may not be completely cooled, and the residual heat may affect the subsequent processing steps and product quality. If the cooling time is too long, although it can ensure that the material is completely cooled, it may waste energy and time, and overcooling may also have adverse effects on the material. Therefore, the cooling time is controlled to 2 to 8 minutes, which can fully cool the material while ensuring the excellent quality of fresh corn food.

[0076] In order to improve the draining effect and meet the needs of industrial continuous production, in some optional embodiments, in the first draining operation, a chain is used to convey the material after the first cooling operation for draining, and air drying is assisted, and the draining time is 1 to 8 minutes; during air drying, 1 to 6 fans are set on the top space of the chain used for conveying for air supply and drying, so as to ensure that the cooling water on the surface of the material can be quickly dried within the above time range, thereby meeting the continuous production needs of industrial applications.

[0077] When the fresh corn food is vacuum-packed corn cobs, in some optional embodiments, the first draining operation also includes sequentially performing a vacuum packaging operation, a sterilization operation and a foreign matter detection operation; after the first draining operation, the cooling water on the surface of the material is fully removed, and by vacuum-packing the material after the first draining operation, the shelf life of the fresh corn food can be effectively extended and oxidation and microbial growth can be prevented; further sterilization operation is performed on the material after the vacuum packaging operation, which can further improve the safety of the fresh corn food and extend the shelf life; by performing a foreign matter detection operation on the material after the sterilization operation, foreign matter that may be introduced during the preparation process, such as metal foreign matter such as nuts, screws, welding slag, etc., can be removed, thereby reducing the risk of food safety and improving the quality of the fresh corn food.

[0078] In some embodiments of the present invention, the vacuum packaging operation uses a vacuum packaging machine to vacuum-pack the corn cob material after the first draining operation, and can be packaged in a retort-resistant packaging bag to improve convenience during consumption.

[0079] In some embodiments of the present invention, the sterilization operation can be carried out in a sterilization kettle. In order to ensure the sterilization effect, the sterilization temperature is controlled to 110°C to 130°C, the sterilization time is controlled to 18 to 30 minutes, and the pressure during the sterilization process is controlled to 0.1Mpa to 0.3Mpa; after the sterilization is completed, secondary cooling is performed to obtain a finished vacuum-packed corn cob food. Before the sterilization operation, the center of the corn cob material has a higher initial temperature after microwave enzyme inactivation, which can further increase the sterilization intensity during the sterilization process to reduce the microbial risk of the product.

[0080] When the fresh corn food is quick-frozen corn cobs, in some optional embodiments, the first draining operation also includes a first quick-freezing operation and a foreign matter detection operation; wherein, the first quick-freezing operation can use a quick-freezing tunnel or a quick-freezing warehouse to quick-freeze the material after the first draining operation, and in the first quick-freezing operation, the quick-freezing temperature is below -30°C, and the quick-freezing time is greater than 20 minutes to ensure that the temperature of the center of the material (the center of the corn cob) is less than -18°C when quick-frozen; by performing a foreign matter detection operation on the material after the first quick-freezing operation, foreign matter that may be introduced during the preparation process, such as metal foreign matter such as nuts, screws, welding slag, etc., can be removed, thereby reducing food safety risks and improving the quality of fresh corn food.

[0081] It should be noted that when the fresh corn food is quick-frozen corn cobs, the first cooling operation can use cooling water and ice water in sequence to cool the material after the enzyme inactivation process. After the material is cooled by cooling water, it is cooled again by ice water, which can effectively reduce the load of the quick-freezing equipment and further improve the quick-freezing efficiency.

[0082] In view of the different types of fresh corn food, in some optional embodiments, when the fresh corn food is quick-frozen corn kernels, the pre-treatment steps include acceptance operation, peeling and silk removal operation, threshing operation, air separation and impurity removal operation, rotary screening operation and rotary water washing operation.

[0083] It can be understood that when the fresh corn food is quick-frozen corn kernels, in the pre-processing process, the materials to be processed are inspected and accepted according to the preset acceptance standards for the fullness of the kernels, the size of the cobs, the color, the variety, the maturity and the presence of foreign matter of the whole ear of corn, so as to ensure that the fresh corn food has a better quality; then the materials after the acceptance are peeled and desilked to remove larger debris such as the corn husk and silk, so as to reduce the subsequent impurity removal costs; the corn cob materials after the peeling and desilking operations are threshed to remove the corn cobs. The rice core is removed to obtain corn kernel material; since the corn kernel material obtained after the threshing operation will inevitably contain more impurities, the material after the threshing operation is subjected to an air separation and impurity removal operation to remove light-density impurities such as corn silk and corn husk in the material, and then the material after the air separation and impurity removal operation is subjected to a rotary screening operation to further remove large-sized impurities and small-sized impurities (such as broken corn kernels). The material after the rotary screening operation is subjected to a rotary water washing operation to effectively remove impurities with lower density, so as to facilitate the preparation of quick-frozen corn kernels with higher quality.

[0084] The main purpose of the air separation and impurity removal operation is to remove light-density impurities. In some optional embodiments of the present invention, in the air separation and impurity removal operation, the material after the threshing operation is lifted to a preset height and then dropped, and wind is used to assist in the falling process of the material, so that light-density impurities such as corn silk and corn husks can be fully separated from the corn kernels by utilizing the difference between wind force and gravity.

[0085] The purpose of the rotary screening operation is to obtain materials of qualified size and remove large and small impurities. In an optional embodiment of the present invention, in the rotary screening operation, the material after the air separation and impurity removal operation is placed in a roller screen for rotary screening; the roller screen is a two-layer roller screen, the inner layer screen has circular holes with an aperture of about 1.5 to 2 cm, and the outer layer screen has elliptical holes with a width of about 0.5 cm and a length of 1 cm, so that large-sized foreign matter can remain in the inner layer screen, and small-sized foreign matter can be screened out through the outer layer screen, and the material retained in the middle layer between the outer layer screen and the inner layer screen is corn kernel material of qualified size, so as to achieve effective removal of large-sized foreign matter and small-sized foreign matter, especially broken corn kernels, in the quick-frozen corn kernels.

[0086] In order to further remove impurities with lower density, in some optional embodiments of the present invention, the rotary water washing operation includes immersing the material after the rotary screening operation in water, performing rotary water washing under water flow disturbance, and placing the material after the rotary water washing on the screen for spray washing. Specifically, a rotary washing machine is used for the rotary water washing operation, the material after the rotary screening operation is immersed in water, and a water spray pipe is provided at the bottom of the water to send water to form water flow disturbance, so as to perform rotary water washing on the surface of the corn kernels, so that impurities with relatively lower density can float on the water surface and be discharged, and the rotary water-washed corn kernels are placed on a single-layer screen for spray washing, and the screen is composed of two sections, the aperture of the front section screen is smaller, and its screen aperture is an elliptical aperture of about 0.5 cm width and 1 cm length, so as to further screen out small-sized impurities, and the aperture size of the rear section screen is larger, and the aperture size is a circular hole of about 1.5 to 2 cm diameter, and qualified-sized materials can leak through the screen, while large-sized impurities are left in the screen and discharged, so as to further screen out large-sized impurities, and obtain cleaner and qualified-sized corn kernels.

[0087] When the fresh corn food is quick-frozen corn kernels, in some optional embodiments of the present invention, the post-processing steps sequentially include a second cooling operation, a second draining operation, a spreading operation, a second quick-freezing operation, a selection operation, a quantitative packaging operation and a foreign matter detection operation. The material after the enzyme inactivation process has a high temperature. After the second cooling operation, the temperature of the corn kernel material can be significantly reduced, which is conducive to improving the processing volume and quick freezing efficiency during the subsequent quick freezing. Since the surface of the corn kernel after the second cooling operation contains cooling water, the cooling water on the surface of the corn kernel can be fully dried after the second draining operation to reduce ice crystals of the quick-frozen corn kernel product and improve the quality of fresh corn food. After the second draining operation, the material can be spread more evenly in the quick freezing equipment after the spreading operation, so as to improve the quick freezing efficiency. After the spreading operation, the material can be quickly reduced to an extremely low temperature in a very short time after the second quick freezing operation to maximize the retention of the original nutritional components and flavor of the corn kernels. After the second quick freezing operation, the material can be screened and graded after the selection operation to ensure the consistency of the product quality of the fresh corn food. After the selection operation, the material can be ensured to be consistent in the number of products in each package after the quantitative packaging operation. Further, the quantitative packaging operation is subjected to a foreign matter detection operation, and foreign matters that may be introduced during the preparation process, such as metal foreign matters such as nuts, screws, and welding slag, can be removed, thereby reducing the risk of food safety and improving the quality of fresh corn food.

[0088] In some optional embodiments of the present invention, in the second cooling operation, room temperature water and cold water are used in turn to cool the material after the enzyme inactivation process, and the cold water temperature is 4-15°C. Compared with a single cooling, cooling the material after the enzyme inactivation process twice by room temperature water and 4-15°C cooling water can significantly reduce the temperature of the corn kernel material before the second quick freezing treatment, thereby improving the processing volume and quick freezing efficiency during the quick freezing treatment.

[0089] Since the second cooling operation adopts water cooling, in some optional embodiments of the present invention, in the second draining operation, a perforated chain conveyor is used to transport the material after the second cooling operation, drain it, and assist in air drying. The perforated chain conveyor is used to transport the material after the second cooling operation, so that the cooling moisture on the surface of the corn kernels can drip naturally, and at the same time, an air drying device equipped with a fan is used to supply air to dry it, so as to quickly remove excess moisture on the surface of the corn kernel material.

[0090] In order to improve the quick-freezing efficiency, in some optional embodiments of the present invention, in the spreading operation, the material after the second draining operation is spread under vibration conditions to ensure that the corn kernel material is more evenly distributed to avoid the formation of lumps or uneven thickness during the second quick-freezing operation; the thickness of the cloth is less than 4 cm, which can ensure the quick-freezing effect and enable the corn kernels to quickly and evenly reach the desired low-temperature state.

[0091] In some optional embodiments of the present invention, the selection operation includes color sorting and / or screening and grading of the material after the second quick-freezing operation; the color sorting process can use color sorting equipment to automatically sort out different-colored particles in the corn kernel material to improve the consistency of the quick-frozen corn kernel product; the screening and grading process can use a grading vibrating screen to screen out corn crumbs and ice crystals produced by quick freezing, and at the same time vibrate and separate the corn kernel materials that are stuck together, so as to improve the quality of the quick-frozen corn kernel product and ensure the excellent quality of fresh corn food.

[0092] In some optional embodiments of the present invention, in the second quick-freezing operation, the quick-freezing temperature is below -30°C. The low temperature environment below -30°C can quickly reduce the temperature of the corn kernel material, thereby retaining the nutritional components and flavor of the corn kernels to the greatest extent. Quickly freezing the material to a center temperature of less than -18°C can effectively prevent the growth of microorganisms and enzyme activity, thereby extending the shelf life of the quick-frozen corn kernel product.

[0093] To facilitate industrial continuous production, in some optional embodiments of the present invention, the first quick freezing operation and the second quick freezing operation freeze the material in a quick freezing tunnel or a quick freezing storehouse. The quick freezing tunnel is usually a closed passage, and the material will be surrounded by a continuous flow of cold air when passing on a conveyor belt, thereby achieving rapid and uniform cooling; the quick freezing storehouse is a larger space, in which refrigeration equipment and circulating fans are installed to ensure a stable and uniform temperature in the storehouse.

[0094] In some optional embodiments of the present invention, the foreign matter detection operation includes using a metal detection device to detect the material. For example, the metal detection device can be a metal detector to efficiently and accurately detect metal foreign matter that may be present in the material, thereby improving the safety of fresh corn food.

[0095] When the fresh corn food is quick-frozen corn kernels or quick-frozen corn cobs, in some optional embodiments of the present invention, the quick-frozen corn kernels or quick-frozen corn cobs obtained after the foreign matter detection operation are frozen in a freezer, and the freezing temperature is less than -18°C to inhibit the growth of microorganisms in the fresh corn food, thereby ensuring that the original flavor, taste and nutritional value of the fresh corn food are retained to the greatest extent.

[0096] Another embodiment of the present invention further provides a fresh corn food, which is prepared according to the preparation method of the above embodiment.

[0097] In order to make the purpose, technical solutions and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. However, the described specific embodiments are only used to explain the present invention and are not used to limit the present invention.

[0098] Example 1

[0099] A method for preparing colored corn vacuum-packed corn cobs, the specific steps are as follows:

[0100] 1. Pre-treatment process

[0101] 1) Acceptance operation: Using colored corn cobs as raw materials, the raw material kernel fullness, cob size, color, variety, maturity and foreign matter are inspected according to the preset acceptance standards to obtain the accepted materials.

[0102] 2) Peeling and silk removal operation: Peeling the qualified materials after acceptance, removing the corn husk and silk, and obtaining the peeled and silk removed materials;

[0103] 3) Head and tail cutting operation: The corn cobs that do not meet the requirements in terms of color, shape, size and tenderness are removed after the peeling and silk removal operations. The heads and tails of the corn cobs with good morphology and quality obtained after the selection are cut off to obtain the materials after the head and tail cutting operations.

[0104] 4) Bubble cleaning operation: Use water immersion bubbling to rinse the material after the head and tail cutting operation. The time of the bubbling cleaning operation is controlled to 2 minutes to obtain the material after the bubbling cleaning operation.

[0105] 5) High-pressure cleaning operation: Use rollers to transport the material after the bubbling cleaning operation, so that the material after the bubbling cleaning operation is cleaned by high-pressure water during the tumbling process. The time of the high-pressure cleaning operation is controlled to be 2 minutes to obtain the material to be inactivated.

[0106] 2. Enzyme inactivation process

[0107] The material to be inactivated is covered with Teflon high temperature cloth and then transported through a conveying mechanism A in a microwave environment. The material is inactivated by microwave for 4 minutes and kept warm for 4 minutes. The conveying mechanism A is provided with 4 microwave generators d.

[0108] 3. Post-processing process

[0109] 1) First cooling operation: the material after the enzyme inactivation process is placed in cooling water for cooling, the cooling water temperature is 4° C., and the first cooling operation time is 2 min.

[0110] 2) The first draining operation: the material after the first cooling operation is conveyed by a chain for draining and assisted by air drying. The draining time is 1 minute. Six fans are provided in the space above the chain.

[0111] 3) Vacuum packaging operation: vacuum packaging the material after the first draining operation.

[0112] 4) Sterilization operation: The vacuum packaging operation is sterilized in a sterilizer at a temperature of 120°C, a sterilization time of 24 minutes, and a pressure range of 0.2Mpa during the sterilization process;

[0113] 5) Foreign matter detection operation: Use metal detection equipment to detect the material after the sterilization operation to remove metal foreign matter and obtain colored corn vacuum-packed corn cobs.

[0114] Example 2

[0115] A method for preparing quick-frozen black corn cobs, the specific steps are as follows:

[0116] 1. Pre-treatment process

[0117] 1) Acceptance operation: Using black corn cobs as raw materials, the raw material kernel fullness, cob size, color, variety, maturity and foreign matter are inspected according to the preset acceptance standards to obtain the accepted materials.

[0118] 2) Peeling and silk removal operation: Peeling the qualified materials after acceptance, removing the corn husk and silk, and obtaining the peeled and silk removed materials;

[0119] 3) Head and tail cutting operation: The corn cobs that do not meet the requirements in terms of color, shape, size and tenderness are removed after the peeling and silk removal operations. The heads and tails of the corn cobs with good morphology and quality obtained after the selection are cut off to obtain the materials after the head and tail cutting operations.

[0120] 4) Bubble cleaning operation: Use water immersion bubbling to rinse the material after the head and tail cutting operation. The time of the bubbling cleaning operation is controlled to 5 minutes to obtain the material after the bubbling cleaning operation.

[0121] 5) High-pressure cleaning operation: Use rollers to transport the material after the bubbling cleaning operation, so that the material after the bubbling cleaning operation is cleaned by high-pressure water during the tumbling process. The time of the high-pressure cleaning operation is controlled to 5 minutes to obtain the material to be inactivated.

[0122] 2. Enzyme inactivation process

[0123] The material to be inactivated is covered with Teflon high temperature cloth and then transported through the transport mechanism A in a microwave environment to inactivate the enzyme for 7 minutes; the microwave treatment of the material to be inactivated is stopped and kept warm for 5 minutes; the transport mechanism A is provided with 3 microwave generators d.

[0124] 3. Post-processing process

[0125] 1) First cooling operation: the material after the enzyme inactivation process is placed in cooling water for cooling, the cooling water temperature is 17° C., and the first cooling operation time is 5 minutes.

[0126] 2) The first draining operation: the material after the first cooling operation is conveyed by a chain for draining and assisted by air drying. The draining time is 5 minutes. Five fans are provided in the space above the chain.

[0127] 3) First quick-freezing operation: The material after the first draining operation is quick-frozen in a quick-freezing tunnel at a quick-freezing temperature below -30°C until the center temperature of the material is less than -18°C.

[0128] 4) Foreign matter detection operation: Use metal detection equipment to detect the material after the first quick-freezing operation to remove metal foreign matter and obtain black corn quick-frozen corn cobs.

[0129] Example 3

[0130] A method for preparing vacuum-packed sweet corn cobs, comprising the following specific steps:

[0131] 1. Pre-treatment process

[0132] 1) Acceptance operation: Using sweet corn cobs as raw materials, the raw material kernel fullness, cob size, color, variety, maturity and foreign matter are inspected according to the preset acceptance standards to obtain the accepted materials.

[0133] 2) Peeling and silk removal operation: Peeling the qualified materials after acceptance, removing the corn husk and silk, and obtaining the peeled and silk removed materials;

[0134] 3) Head and tail cutting operation: The corn cobs that do not meet the requirements in terms of color, shape, size and tenderness are removed after the peeling and silk removal operations. The heads and tails of the corn cobs with good morphology and quality obtained after the selection are cut off to obtain the materials after the head and tail cutting operations.

[0135] 4) Bubble cleaning operation: Use water immersion bubbling to rinse the material after the head and tail cutting operation. The time of the bubbling cleaning operation is controlled to 8 minutes to obtain the material after the bubbling cleaning operation.

[0136] 5) High-pressure cleaning operation: A roller is used to transport the material after the bubbling cleaning operation, so that the material after the bubbling cleaning operation is cleaned by high-pressure water during the tumbling process. The time of the high-pressure cleaning operation is controlled to be 8 minutes to obtain the material to be inactivated.

[0137] 2. Enzyme inactivation process

[0138] The material to be inactivated is covered with Teflon high temperature cloth and then transported through the transport mechanism A in a microwave environment to inactivate the enzyme for 10 minutes; the microwave treatment of the material to be inactivated is stopped and kept warm for 10 minutes; the transport mechanism A is provided with 4 microwave generators d.

[0139] 3. Post-processing process

[0140] 1) First cooling operation: the material after the enzyme inactivation step is placed in cooling water for cooling, the cooling water temperature is 30° C., and the first cooling operation time is 8 minutes.

[0141] 2) The first draining operation: the material after the first cooling operation is conveyed by a chain for draining and assisted by air drying. The draining time is 8 minutes. Four fans are provided in the space above the chain.

[0142] 3) Vacuum packaging operation: vacuum pack the material after the first draining operation, and vacuum pack the sweet corn cobs.

[0143] Example 4

[0144] A method for preparing quick-frozen black corn kernels, comprising the following specific steps:

[0145] 1. Pre-treatment process

[0146] 1) Acceptance operation: Using black corn cobs as raw materials, the raw material kernel fullness, cob size, color, variety, maturity and foreign matter are inspected according to the preset acceptance standards to obtain the accepted materials.

[0147] 2) Peeling and de-threading operation: Peel the qualified materials after acceptance, remove the corn husk and threads, and obtain the materials after peeling and de-threading operation.

[0148] 3) Threshing operation: threshing the material after the peeling and silk removal operation to obtain the material after the threshing operation.

[0149] 4) Wind selection and impurity removal operation: The material after the threshing operation is lifted to a preset height and then falls, and wind is blown during the falling process to obtain the material after the wind selection and impurity removal operation.

[0150] 5) Rotary screening operation: the material after the air separation and impurity removal operation is placed in a roller screen for rotary screening to obtain the material after the rotary screening operation.

[0151] 6) Rotary water washing operation: immerse the material after the rotary screening operation in water, perform rotary water washing under water flow disturbance, place the material after the rotary water washing on the screen for spray washing, and obtain the material to be inactivated.

[0152] 2. Enzyme inactivation process

[0153] The material to be inactivated is covered with Teflon high temperature cloth and then transported through the conveying mechanism A in a microwave environment to inactivate the enzyme for 1 minute; the microwave treatment of the material to be inactivated is stopped and kept warm for 5 minutes; the conveying mechanism A is provided with 4 microwave generators d.

[0154] 3. Post-processing process

[0155] 1) Second cooling operation: Use normal temperature water and cold water in turn to cool the material after the enzyme inactivation process, and the cold water temperature is 4-10°C.

[0156] 2) Second draining operation: Use a perforated chain conveyor to transport the material after the second cooling operation, drain it, and assist in air drying.

[0157] 3) Material spreading operation: the material after the second draining operation is spread under vibration conditions, and the thickness of the material after the spreading operation is 1 cm.

[0158] 4) Second quick-freezing operation: The material after the distribution operation is quick-frozen in a quick-freezing tunnel, the quick-freezing temperature is -36°C, the quick-freezing time is 10 minutes, and the central temperature of the corn kernel material is less than -18°C after the quick-freezing.

[0159] 5) Selection operation: Use a graded vibrating screen to screen out corn crumbs and ice crystals in the material after the second quick-freezing operation, and vibrate to separate corn kernels that stick together; further use a color sorter to automatically sort out the different-colored particles in the material after the graded vibrating screen processing.

[0160] 6) Quantitative packaging operation: Quantitative packaging of materials after selection operation to ensure that the quantity of products in each package is consistent.

[0161] 7) Foreign matter detection operation: Use metal detection equipment to detect the material after the quantitative packaging operation, remove the metal foreign matter in the material, and obtain black corn quick-frozen corn kernels.

[0162] 8) Frozen storage: The quick-frozen black corn kernels are stored in a frozen warehouse at a temperature below -18°C.

[0163] Example 5

[0164] A method for preparing quick-frozen sweet corn kernels, the specific steps are as follows:

[0165] 1. Pre-treatment process

[0166] 1) Acceptance operation: Using sweet corn cobs as raw materials, the raw material kernel fullness, cob size, color, variety, maturity and foreign matter are inspected according to the preset acceptance standards to obtain the accepted materials.

[0167] 2) Peeling and de-threading operation: Peel the qualified materials after acceptance, remove the corn husk and threads, and obtain the materials after peeling and de-threading operation.

[0168] 3) Threshing operation: threshing the material after the peeling and silk removal operation to obtain the material after the threshing operation.

[0169] 4) Wind selection and impurity removal operation: The material after the threshing operation is lifted to a preset height and then falls, and wind is blown during the falling process to obtain the material after the wind selection and impurity removal operation.

[0170] 5) Rotary screening operation: the material after the air separation and impurity removal operation is placed in a roller screen for rotary screening to obtain the material after the rotary screening operation.

[0171] 6) Rotary water washing operation: immerse the material after the rotary screening operation in water, perform rotary water washing under water flow disturbance, place the material after the rotary water washing on the screen for spray washing, and obtain the material to be inactivated.

[0172] 2. Enzyme inactivation process

[0173] The material to be inactivated is covered with Teflon high temperature cloth and then transported through the transport mechanism A in a microwave environment to inactivate the enzyme for 6 minutes; the microwave treatment of the material to be inactivated is stopped and kept warm for 3 minutes; the transport mechanism A is provided with 3 microwave generators d.

[0174] 3. Post-processing process

[0175] 1) Second cooling operation: Use normal temperature water and cold water in turn to cool the material after the enzyme inactivation process, and the cold water temperature is 4-10°C.

[0176] 2) Second draining operation: Use a perforated chain conveyor to transport the material after the second cooling operation, drain it, and assist in air drying.

[0177] 3) Material spreading operation: the material after the second draining operation is spread under vibration conditions, and the thickness of the material after the spreading operation is 1 cm.

[0178] 4) Second quick-freezing operation: The material after the distribution operation is quick-frozen in a quick-freezing tunnel, the quick-freezing temperature is -36°C, the quick-freezing time is 10 minutes, and the central temperature of the corn kernel material is less than -18°C after the quick-freezing.

[0179] 5) Selection operation: Use a graded vibrating screen to screen out corn crumbs and ice crystals in the material after the second quick-freezing operation, and vibrate to separate corn kernels that stick together; further use a color sorter to automatically sort out the different-colored particles in the material after the graded vibrating screen processing.

[0180] 6) Quantitative packaging operation: Quantitative packaging of materials after selection operation to ensure that the quantity of products in each package is consistent.

[0181] 7) Foreign matter detection operation: Use metal detection equipment to detect the material after the quantitative packaging operation, remove the metal foreign matter in the material, and obtain sweet corn quick-frozen corn kernels.

[0182] 8) Frozen storage: The quick-frozen black corn kernels are stored in a frozen warehouse at a temperature below -18°C.

[0183] Example 6

[0184] A method for preparing quick-frozen sweet corn kernels, the specific steps are as follows:

[0185] 1. Pre-treatment process

[0186] 1) Acceptance operation: Using sweet corn cobs as raw materials, the raw material kernel fullness, cob size, color, variety, maturity and foreign matter are inspected according to the preset acceptance standards to obtain the accepted materials.

[0187] 2) Peeling and de-threading operation: Peel the qualified materials after acceptance, remove the corn husk and threads, and obtain the materials after peeling and de-threading operation.

[0188] 3) Threshing operation: threshing the material after the peeling and silk removal operation to obtain the material after the threshing operation.

[0189] 4) Wind selection and impurity removal operation: The material after the threshing operation is lifted to a preset height and then falls, and wind is blown during the falling process to obtain the material after the wind selection and impurity removal operation.

[0190] 5) Rotary screening operation: the material after the air separation and impurity removal operation is placed in a roller screen for rotary screening to obtain the material after the rotary screening operation.

[0191] 6) Rotary water washing operation: immerse the material after the rotary screening operation in water, perform rotary water washing under water flow disturbance, place the material after the rotary water washing on the screen for spray washing, and obtain the material to be inactivated.

[0192] 2. Enzyme inactivation process

[0193] The material to be inactivated is covered with Teflon high temperature cloth and then transported through a conveying mechanism A in a microwave environment. The microwave inactivates the enzyme for 10 minutes and the material is kept warm for 2 minutes. The conveying mechanism A is provided with 3 microwave generators d.

[0194] 3. Post-processing process

[0195] 1) Second cooling operation: Use normal temperature water and cold water in turn to cool the material after the enzyme inactivation process, and the cold water temperature is 4-10°C.

[0196] 2) Second draining operation: Use a perforated chain conveyor to transport the material after the second cooling operation, drain it, and assist in air drying.

[0197] 3) Material spreading operation: the material after the second draining operation is spread under vibration conditions, and the thickness of the material after the spreading operation is 1 cm.

[0198] 4) Second quick-freezing operation: The material after the distribution operation is quick-frozen in a quick-freezing tunnel, the quick-freezing temperature is -36°C, the quick-freezing time is 10 minutes, and the central temperature of the corn kernel material is less than -18°C after the quick-freezing.

[0199] 5) Selection operation: Use a graded vibrating screen to screen out corn crumbs and ice crystals in the material after the second quick-freezing operation, and vibrate to separate corn kernels that stick together; further use a color sorter to automatically sort out the different-colored particles in the material after the graded vibrating screen processing.

[0200] 6) Quantitative packaging operation: Quantitative packaging of materials after selection operation to ensure that the quantity of products in each package is consistent.

[0201] 7) Foreign matter detection operation: Use metal detection equipment to detect the material after the quantitative packaging operation, remove the metal foreign matter in the material, and obtain sweet corn quick-frozen corn kernels.

[0202] 8) Frozen storage: The quick-frozen black corn kernels are stored in a frozen warehouse at a temperature below -18°C.

[0203] Comparative Example 1

[0204] A method for preparing quick-frozen black corn cobs, the specific steps are as follows:

[0205] 1. Pre-treatment process

[0206] 1) Acceptance operation: Using black corn cobs as raw materials, the raw material kernel fullness, cob size, color, variety, maturity and foreign matter are inspected according to the preset acceptance standards to obtain the accepted materials.

[0207] 2) Peeling and silk removal operation: Peeling the qualified materials after acceptance, removing the corn husk and silk, and obtaining the peeled and silk removed materials;

[0208] 3) Spray cleaning operation: Use rollers to transport the material after the peeling and de-filamenting operation, so that the material after the peeling and de-filamenting operation is cleaned by high-pressure water during the rolling process, and obtains the material after the spray cleaning operation.

[0209] 4) Head and tail cutting operation: The material after the spray cleaning operation is preliminarily selected to remove corn cobs that do not meet the requirements in terms of color, shape, size and maturity. The heads and tails of the corn cobs with good morphology and quality obtained after selection are cut off to obtain the material to be inactivated.

[0210] 2. Enzyme inactivation process

[0211] The material to be inactivated was blanched with hot water at 95°C for 8 minutes to initially slow down the corn kernels on the surface of the material.

[0212] 3. Post-processing process

[0213] 1) First cooling operation: the material after the enzyme inactivation process is placed in normal temperature water for cooling. The first cooling operation time is 3 minutes.

[0214] 2) The first draining operation: the material after the first cooling operation is conveyed by a chain for draining and assisted by air drying. The draining time is 5 minutes. Five fans are provided in the space above the chain.

[0215] 3) First quick-freezing operation: The material after the first draining operation is quick-frozen in a quick-freezing tunnel at a quick-freezing temperature of below -30°C until the center temperature of the material is less than -18°C, thereby obtaining quick-frozen black corn cobs.

[0216] Comparative Example 2

[0217] A method for preparing colored corn vacuum-packed corn cobs, the specific steps are as follows:

[0218] 1. Pre-treatment process

[0219] 1) Acceptance operation: Using colored corn cobs as raw materials, the raw material kernel fullness, cob size, color, variety, maturity and foreign matter are inspected according to the preset acceptance standards to obtain the accepted materials.

[0220] 2) Peeling and silk removal operation: Peeling the qualified materials after acceptance, removing the corn husk and silk, and obtaining the peeled and silk removed materials;

[0221] 3) Spray cleaning operation: Use rollers to transport the material after the peeling and de-filamenting operation, so that the material after the peeling and de-filamenting operation is cleaned by high-pressure water during the rolling process, and obtains the material after the spray cleaning operation.

[0222] 4) Head and tail cutting operation: The material after the spray cleaning operation is preliminarily selected to remove corn cobs that do not meet the requirements in terms of color, shape, size and maturity. The heads and tails of the corn cobs with good morphology and quality obtained after selection are cut off to obtain the material to be inactivated.

[0223] 2. Enzyme inactivation process

[0224] The material to be inactivated was blanched with hot water at 95°C for 8 minutes to initially slow down the corn kernels on the surface of the material.

[0225] 3. Post-processing process

[0226] 1) First cooling operation: the material after the enzyme inactivation process is placed in normal temperature water for cooling. The first cooling operation time is 3 minutes.

[0227] 2) The first draining operation: the material after the first cooling operation is conveyed by a chain for draining and assisted by air drying. The draining time is 1 minute. Six fans are provided in the space above the chain.

[0228] 3) Vacuum packaging operation: vacuum packaging the material after the first draining operation.

[0229] 4) Sterilization operation: The vacuum packaging operation is sterilized in a sterilizer at a temperature of 120°C, a sterilization time of 24 minutes, and a pressure range of 0.2Mpa during the sterilization process;

[0230] 5) Foreign matter detection operation: Use metal detection equipment to detect the material after the sterilization operation to remove metal foreign matter and obtain colored corn vacuum-packed corn cobs.

[0231] Comparative Example 3

[0232] A method for preparing quick-frozen black corn kernels, comprising the following specific steps:

[0233] 1. Pre-treatment process

[0234] 1) Acceptance operation: Using black corn cobs as raw materials, the raw material kernel fullness, cob size, color, variety, maturity and foreign matter are inspected according to the preset acceptance standards to obtain the accepted materials.

[0235] 2) Peeling and de-threading operation: Peel the qualified materials after acceptance, remove the corn husk and threads, and obtain the materials after peeling and de-threading operation.

[0236] 3) Threshing and cleaning: threshing the material after peeling and silk removal, and cleaning the threshed material to obtain the material to be inactivated.

[0237] 2. Enzyme inactivation process

[0238] The material to be inactivated is placed in hot water for blanching to inactivate the enzyme. The blanching temperature is 95°C and the blanching time is 10 minutes. During the blanching process, the hot water is in direct contact with the corn kernel material and the blanching water is heated by steam.

[0239] 3. Post-processing process

[0240] 1) Second cooling operation: Use normal temperature water to cool the material after the enzyme inactivation process.

[0241] 2) Sorting operation: Manually sort the materials after the second cooling operation to remove foreign objects such as different-colored grains, broken grains, corn silk and debris.

[0242] 3) Second draining operation: Use a perforated chain conveyor to transport the material after the selection operation, drain it, and assist in air drying.

[0243] 4) Second quick-freezing operation: Use a quick-freezing tunnel to quick-freeze the material after the distribution operation, the quick-freezing temperature is less than -30°C, the quick-freezing time is greater than 10 minutes, and the center temperature of the corn kernel material is less than -18°C after the quick-freezing.

[0244] 5) Selection operation: Use a graded vibrating screen to screen out corn crumbs and ice crystals in the material after the second quick-freezing operation, and vibrate and separate the corn kernels that are stuck together.

[0245] 6) Quantitative packaging operation: quantitatively package the materials after the selection operation to ensure that the quantity of products in each package is consistent, and obtain black corn quick-frozen corn kernels.

[0246] 8) Frozen storage: The quick-frozen black corn kernels are stored in a frozen warehouse at a temperature below -18°C.

[0247] Comparative Example 4

[0248] A method for preparing white corn vacuum-packed corn cobs, the specific steps are as follows:

[0249] 1. Pre-treatment process

[0250] 1) Acceptance operation: Using white corn cobs as raw materials, the raw material kernel fullness, cob size, color, variety, maturity and foreign matter are inspected according to the preset acceptance standards to obtain the accepted materials.

[0251] 2) Peeling and silk removal operation: Peeling the qualified materials after acceptance, removing the corn husk and silk, and obtaining the peeled and silk removed materials;

[0252] 3) Head and tail cutting operation: The corn cobs that do not meet the requirements in terms of color, shape, size and tenderness are removed after the peeling and silk removal operations. The heads and tails of the corn cobs with good morphology and quality obtained after the selection are cut off to obtain the materials after the head and tail cutting operations.

[0253] 4) Bubble cleaning operation: Use water immersion bubbling to rinse the material after the head and tail cutting operation. The time of the bubbling cleaning operation is controlled to 2 minutes to obtain the material after the bubbling cleaning operation.

[0254] 5) High-pressure cleaning operation: Use rollers to transport the material after the bubbling cleaning operation, so that the material after the bubbling cleaning operation is cleaned by high-pressure water during the tumbling process. The time of the high-pressure cleaning operation is controlled to be 2 minutes to obtain the material to be inactivated.

[0255] 2. Enzyme inactivation process

[0256] The material to be inactivated is exposed to a microwave environment and transported through a conveying mechanism A. The material is inactivated by microwaves for 4 minutes and kept warm for 4 minutes. The conveying mechanism A is provided with 4 microwave generators d.

[0257] 3. Post-processing process

[0258] 1) First cooling operation: the material after the enzyme inactivation process is placed in cooling water for cooling, the cooling water temperature is 4° C., and the first cooling operation time is 2 min.

[0259] 2) The first draining operation: the material after the first cooling operation is conveyed by a chain for draining and assisted by air drying. The draining time is 1 minute. Six fans are provided in the space above the chain.

[0260] 3) Vacuum packaging operation: vacuum packaging the material after the first draining operation.

[0261] 4) Sterilization operation: The vacuum packaging operation is sterilized in a sterilizer at a temperature of 120°C, a sterilization time of 24 minutes, and a pressure range of 0.2Mpa during the sterilization process;

[0262] 5) Foreign matter detection operation: Use metal detection equipment to detect the material after the sterilization operation to remove metal foreign matter and obtain white corn vacuum-packed corn cobs.

[0263] It should be noted that in the above embodiments and comparative examples, the conveying mechanism A is derived from the microwave processing equipment of Shandong Liwei Microwave Equipment Co., Ltd., and the detailed parameter specifications are as follows:

[0264] Equipment model: LW-20HMV; operating frequency: 2450±50MHz; rated input apparent power: ≤25KW; microwave output power: ≥20KW; working process temperature: 70~200℃ (controllable); equipment cooling method: water cooling / air cooling; working time: continuous 24h; inlet and outlet material height: 40~100mm; conveyor belt height: 600~1000mm; transmission speed: 0~4.5m / min; dehydration rate: 16~20Kg / h; overall dimensions (length*width*height): 8640*1220*2200mm; conveyor belt width: 500±100mm; microwave leakage standard: national standard ≤5mw / cm 2 .

[0265] Fresh corn food prepared according to the process of Example 1 and Comparative Example 2 was sliced ​​radially along the corn cob, and peroxidase activity was tested under the same reagent. The photos after the test are as follows: Figure 1 and Figure 2 shown.

[0266] The material after being cooled with room temperature water in the second cooling operation in Example 4 was photographed with room temperature water, and the material after the enzyme inactivation step in Comparative Example 3 was photographed with blanching water. The obtained photos are as follows: Figure 3 and Figure 4 The fresh corn food prepared by the process method of Comparative Example 4 was photographed, and the obtained photo was as shown in FIG. Figure 5 shown.

[0267] The materials in the preparation process of Example 1 and Comparative Example 2 were respectively tested for the center temperature of the corn cob before the sterilization operation, and the sterilization intensity F0 value after the sterilization operation. The test results are shown in Table 1 below:

[0268] Table 1. Test results of corn cob center temperature and sterilization intensity

[0269]

[0270] It should be noted that the F0 value in the embodiments of the present application refers to the standard sterilization time, that is, the equivalent sterilization time at 121°C. The larger the value, the higher the sterilization intensity. For example, the F0 value is the time (min) equivalent to the sterilization effect produced when Z is 10°C at a certain sterilization temperature T (such as the sterilization temperature of 126°C in Example 4) and the sterilization effect produced when 121°C and Z value is 10°C. The F0 value can be calculated using the following formula:

[0271] F0=ΔtΣ10(T-121 / Z)

[0272] Wherein, “Δt” is the test interval at temperature T; “T” is the temperature of the product at sterilization time t; and “Z” is the temperature coefficient.

[0273] The anthocyanin content of the fresh corn foods prepared in Example 2, Example 4, Comparative Example 1 and Comparative Example 3 was tested respectively, and the test results are shown in Table 2 below:

[0274] Table 2. Anthocyanin content test results

[0275]

[0276] according to Figure 1 and Figure 2 It can be seen that compared with Example 1, the corn cob color of the fresh corn food in Comparative Example 2 is darker (such as Figure 2 As shown in the figure, the enzyme inactivation of the corn cob of the fresh corn food in Comparative Example 2 is not complete. This is because when the enzyme is inactivated by blanching with hot water, the heat needs to be transferred from the corn kernels to the corn cobs. After the enzymes on the surface of the whole ear of corn are fully inactivated, the corn cobs inside cannot be fully inactivated due to the low heating temperature. In contrast, the corn cobs of the fresh corn food in Example 1 are lighter in color (as shown in the figure). Figure 1 As shown, the enzyme inactivation is more thorough. This verifies that in the embodiment of the present invention, the material to be inactivated is covered with a flexible protective member and then inactivated by microwaves in a microwave environment. The microwave can focus on heating the corncob due to its high water content, making the enzyme inactivation of the corncob more thorough, which is beneficial to significantly improve the overall enzyme inactivation effect of fresh corn food, thereby increasing the shelf life of the fresh corn food and ensuring that it maintains good quality after long-term storage.

[0277] In terms of sterilization, referring to Table 1, in Example 1, the material to be inactivated is covered with a flexible protective piece and then inactivated by microwave in a microwave environment. Microwaves can focus on heating the corn cob according to the high water content of the corn cob. The center temperature of the corn cob is 90°C before the sterilization operation, while in Comparative Example 2, the enzyme is only inactivated by blanching in hot water, and the center of the corn cob is not fully heated. The center temperature of the corn cob before the sterilization operation is only 25°C at room temperature. After the same sterilization operation, the sterilization intensity F0 values ​​of the two are quite different. The sterilization intensity of Comparative Example 2 is only 3.0min, while that of Example 1 can reach 6.0min. This indicates that in the embodiments of the present application, the material to be inactivated is covered with a flexible protective piece and then inactivated by microwave in a microwave environment, and the sterilization effect is better, which can significantly improve the product quality.

[0278] It can be understood that the enzyme inactivation process of Comparative Example 2 uses hot water blanching to inactivate the enzyme inactivation material. The heat needs to be transferred from the corn kernels to the corn cobs. The corn cobs are not sufficiently heated during the enzyme inactivation process, and the enzyme inactivation is not complete. The center temperature of the corn cobs is low before the sterilization operation, and the sterilization effect is poor. The quality of the fresh corn food is seriously degraded after long-term storage. In addition, in the enzyme inactivation process of Comparative Example 2, the corn is directly in contact with the high-temperature blanching water, which causes serious loss of nutrients and pigment substances in the fresh corn food (the loss rate of soluble sugar content is about 38%, and the loss rate of VC is about 50%). In addition, there is only one spray cleaning operation before the enzyme inactivation process of Comparative Example 2, which easily leads to residual impurities such as corn silk and debris in the fresh corn food, resulting in serious loss of nutrients in the fresh corn food and poor quality. In the enzyme inactivation process of Example 1, After the enzyme-inactivating material is covered with a flexible protective piece, microwave enzyme inactivation is performed in a microwave environment. Microwaves can focus on heating the corn cob due to its high water content. The corn cob is fully heated, making the enzyme inactivation of the corn cob more thorough. The center temperature of the corn cob is higher before the sterilization operation, which is beneficial to significantly improve the overall enzyme inactivation and sterilization effects of the fresh corn food, thereby increasing the shelf life of the fresh corn food and ensuring that it maintains good quality after long-term storage. In addition, during the preparation of the fresh corn food in Example 1, the corn is not in direct contact with high-temperature water, which effectively reduces the loss of water-soluble nutrients such as anthocyanins, and its nutritional components are better retained. In addition, in Example 1, the bubbling cleaning operation combined with the high-pressure cleaning operation can better remove impurities in the fresh corn food, so that the prepared fresh corn food has more excellent quality.

[0279] Furthermore, the main difference between Comparative Example 4 and Example 1 is that in the enzyme inactivation process of Comparative Example 4, the material to be inactivated is not covered with a flexible protective member, but is exposed to a microwave environment for microwave enzyme inactivation. Figure 5It can be seen that in Comparative Example 4, the surface of the fresh corn food is partially darker and partially whitish. The starch in the darker part of the corn kernels is gelatinized, while the starch in the whitish part of the corn kernels is not gelatinized, and the corn kernels still have enzyme activity. This is because the material to be inactivated is exposed to the microwave environment for microwave enzyme inactivation. The moisture generated by the material to be inactivated after heating is lost along with the heat, resulting in uneven heating of the material to be inactivated, and thus resulting in poor enzyme inactivation effect. This verifies that in the embodiment of the present invention, after the material to be inactivated is covered with a flexible protective member, microwave enzyme inactivation is performed in a microwave environment, which is beneficial to significantly improve the overall enzyme inactivation effect of the fresh corn food.

[0280] It is worth noting that in Example 1 of the present application, the material to be inactivated is covered with a flexible protective piece and then inactivated by microwave in a microwave environment. The flexible protective piece has good thermal insulation and moisture retention properties. Compared with covering with other protective materials with poor thermal insulation and moisture retention properties, or not covering with a protective material as in Comparative Example 4, the energy consumption and product water loss rate are lower and the production efficiency is higher.

[0281] Further, referring to Table 2, compared with Example 2, the anthocyanin content of the fresh corn food obtained in Comparative Example 1 is 15 mg / kg, and the anthocyanin content is relatively low. This is because when the hot water is blanched to inactivate the enzyme, the high-temperature blanching water directly contacts the corn, so that the anthocyanins in the corn are dissolved in the blanching water, and the anthocyanins and other nutrients in the fresh corn food are seriously lost; while in the enzyme inactivation process of Example 2, the enzyme inactivation material is covered with a flexible protective part and then microwaved under a microwave environment for enzyme inactivation. During the enzyme inactivation process, there is no need for direct contact with high-temperature water, which effectively reduces the loss of water-soluble nutrients such as anthocyanins. The fresh corn food obtained in Example 2 has an anthocyanin content of up to 25 mg / kg, and its nutritional components are better retained.

[0282] In addition, compared with Example 2, Comparative Example 1 has only one spray cleaning operation before the enzyme inactivation process, which easily leads to residual impurities such as corn silk and debris in the fresh corn food. However, Example 2 combines the bubbling cleaning operation with the high-pressure cleaning operation, which can better remove impurities in the fresh corn food, so that the prepared fresh corn food has better quality.

[0283] Continue to refer Figure 3 , Figure 4 As shown in Table 2, Comparative Example 3 is compared with Example 4. In the enzyme inactivation process of Comparative Example 3, hot water blanching is used to inactivate the enzymes in the black corn kernels. After the enzyme inactivation, a large amount of anthocyanins in the corn are dissolved in the blanching water, making the blanching water black (reference Figure 3As shown), the anthocyanin content of the prepared fresh corn food is only 15 mg / kg, and the anthocyanin loss is serious. In addition, in Comparative Example 3, there is only one cleaning after the early threshing, and no color sorting and foreign matter detection operations are performed after the enzyme inactivation. The risk of foreign matter in the fresh corn food is relatively high. At the same time, there is only one room temperature water cooling before the second quick freezing operation, which cannot further reduce the material temperature of the corn kernels when entering the quick freezing tunnel, thereby increasing energy consumption and reducing the quick freezing efficiency. In contrast, in Example 4, in the enzyme inactivation process of Example 4, the enzyme inactivation material is covered with a flexible protective member and then microwave enzyme inactivation is performed under a microwave environment. When the material after the enzyme inactivation process undergoes the second cooling operation, after the corn kernels are soaked in room temperature water, the room temperature water is still transparent (reference Figure 4 ), anthocyanins are not dissolved in water in large quantities, the anthocyanin content of the prepared fresh corn food is as high as 25 mg / kg, and anthocyanins and other nutrients are fully retained. In addition, before the enzyme inactivation in Example 4, the corn kernels are subjected to air selection and impurity removal operations, rotary screening operations and rotary water washing operations, and after the enzyme inactivation process, selection operations and foreign matter detection operations are also performed, so that foreign matter impurities in the fresh corn food can be fully removed, so as to improve the nutritional value and quality of the fresh corn food while effectively ensuring food safety.

[0284] It can be seen that according to the preparation method of the embodiment of the present invention, the selective heating and enzyme inactivation of fresh corn using microwave enzyme inactivation technology can effectively improve the enzyme inactivation effect, while retaining rich nutrients, significantly improving the quality of fresh corn food, and having broader application prospects and commercial value.

[0285] The various technical features described above can be combined arbitrarily. Although all possible combinations of these technical features are not described, any combination of these technical features should be considered to be covered by this specification as long as there is no contradiction in such combination.

[0286] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing fresh corn food, characterized in that: The process comprises sequentially performing a pre-treatment process, an enzyme inactivation process and a post-treatment process on the material to be processed to obtain fresh corn food; The enzyme inactivation process includes covering the material to be inactivated with a flexible protective piece and then performing microwave inactivation under a microwave environment.

2. The method for preparing fresh corn food according to claim 1, characterized in that: The enzyme inactivation process specifically comprises: Covering the material to be inactivated with a flexible protective member and conveying it under a microwave environment for inactivating the enzyme for a first predetermined time; Optionally, the first predetermined time is 1 to 10 minutes, preferably 4 to 10 minutes.

3. The method for preparing fresh corn food according to claim 1 or 2, characterized in that: The enzyme inactivation step further comprises: stopping the microwave treatment of the material to be inactivated by microwave and keeping the material incubated for a second predetermined time; Preferably, the second predetermined time is 0.1 to 10 minutes.

4. The method for preparing fresh corn food according to any one of claims 1 to 3, characterized in that: The flexible protective member includes at least one of Teflon high temperature cloth, silicone cloth or polyester film.

5. The method for preparing fresh corn food according to any one of claims 1 to 4, characterized in that: When the fresh corn food is quick-frozen corn cobs or vacuum-packed corn cobs, the pre-treatment process includes bubbling cleaning operation and high-pressure cleaning operation; Optionally, in the bubbling cleaning operation, water immersion bubbling flushing is adopted; Optionally, during the high-pressure cleaning operation, a roller is used to transport the material after the bubbling cleaning operation, so that the material is cleaned by high-pressure water during the tumbling process.

6. The method for preparing fresh corn food according to any one of claims 1 to 5, characterized in that: When the fresh corn food is quick-frozen corn cobs or vacuum-packed corn cobs, the post-processing step includes a first cooling operation; Optionally, in the first cooling operation, the material after the enzyme inactivation step is immersed in cooling water for cooling, the cooling water temperature is 4° C. to 30° C., and the cooling time is 2 to 8 minutes.

7. The method for preparing fresh corn food according to any one of claims 1 to 6, characterized in that: When the fresh corn food is a vacuum-packed corn cob, the post-processing process further includes a vacuum packaging operation, a sterilization operation and a foreign matter detection operation; optionally, the sterilization temperature is 110° C. to 130° C., the sterilization time is 18 to 30 minutes, and the pressure range during the sterilization process is 0.1 MPa to 0.3 MPa; or When the fresh corn food is quick-frozen corn cobs, the post-processing process also includes a first quick-freezing operation and a foreign matter detection operation; optionally, in the first quick-freezing operation, the quick-freezing temperature is below -30°C, and the material is quick-frozen to a center temperature of less than -18°C.

8. The method for preparing fresh corn food according to any one of claims 1 to 7, characterized in that: When the fresh corn food is quick-frozen corn kernels, the pre-treatment process includes air separation and impurity removal operation, rotary screening operation and rotary water washing operation; Optionally, in the wind separation and impurity removal operation, the material is lifted to a preset height and then dropped, and wind blowing is used to assist in the falling process of the material; Optionally, in the rotary screening operation, the material after the air separation and impurity removal operation is placed in a rolling screen for rotary screening; Optionally, the rotary water washing operation includes immersing the material after the rotary screening operation in water, performing rotary water washing under water flow disturbance, and placing the material after the rotary water washing on a screen for spray washing.

9. The method for preparing fresh corn food according to any one of claims 1 to 8, characterized in that: When the fresh corn food is quick-frozen corn kernels, the post-processing steps include a second cooling operation, a spreading operation, a second quick-freezing operation, a selection operation, a quantitative packaging operation, and a foreign matter detection operation; Optionally, in the second cooling operation, normal temperature water and cold water are used in sequence to cool the material after the enzyme inactivation step, and the temperature of the cold water is 4-15° C.; Optionally, in the material laying operation, the material is laid under vibration conditions, and the thickness of the material is less than 4 cm; Optionally, the selection operation includes color sorting and / or screening and grading the material after the second quick-freezing operation.

10. The method for preparing fresh corn food according to any one of claims 1 to 9, characterized in that: In the second quick freezing operation, the quick freezing temperature is below -30°C, and the material is quick frozen until the center temperature is less than -18°C; Optionally, the second quick-freezing operation freezes the material in a quick-freezing tunnel or a quick-freezing warehouse.

11. A fresh corn food, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 10.

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