Shrimp super-fresh cryopreservation method

Abstract

The invention relates to the technical field of cryopreservation, in particular to a superfresh cryopreservation method for shrimps. According to the technical scheme, the method comprises the following steps: S1, pretreatment of fresh shrimps: removing heads, shells and shrimp lines of the fresh shrimps to prepare shrimp meat, and draining the shrimp meat until the surface of the shrimp meat is free of water; s2, sauce preparation: soybeans, water, yeast and peanuts are used as raw materials, after raw material treatment, soaking, cooking, cooling, inoculation, salt stirring fermentation and pulping are performed, vegetable oil, sugar and garlic are added, and the mixture is stewed into sauce with slow fire; s3, stirring and preserving: uniformly mixing the pretreated shrimp meat with the sauce according to a ratio of 1 kg of shrimp meat to 1 liang of sauce, performing conventional cryopreservation, and wrapping the shrimp meat with the sauce as a freezing medium to inhibit damage of ice crystals to shrimp meat cells. Through the synergistic effect of a unique sauce formula and a precise operation process, multiple protection barriers are constructed, generation of ice crystals is effectively reduced, oxidative deterioration is delayed, and more than 90% of freshness, taste and nutritional ingredients of the shrimp meat can be reserved without a chemical water-retaining agent.

Description

Technical Field

[0001] The invention relates to the technical field of frozen preservation, and in particular to a method for ultra-fresh frozen preservation of shrimps. Background Art

[0002] Shrimp, a popular seafood product, is rich in high-quality protein, unsaturated fatty acids, and a variety of vitamins and minerals, possessing exceptional nutritional value. However, shrimp are prone to spoilage after harvest, making effective cryopreservation techniques crucial for maintaining their quality. Currently, traditional shrimp cryopreservation methods cause water within the shrimp to form ice crystals during the freezing process. These ice crystals form rapidly and are large in size. These sharp ice crystals easily pierce the shrimp's cell membranes, causing nutrients to escape and disrupting the cell structure. This can lead to loose texture and a poor taste after thawing, severely impacting the shrimp's freshness and quality. Nutrients in shrimp are easily lost during the freezing and thawing process. The formation and melting of ice crystals disrupt the cell structure, causing nutrients to be lost along with the water. Furthermore, traditional cryopreservation methods struggle to effectively prevent oxidative deterioration during storage, further accelerating nutrient loss.

[0003] To reduce ice crystal damage to shrimp, some freezing methods use chemical water-retaining agents. While these agents can improve shrimp's water retention and texture to a certain extent, long-term consumption of shrimp products containing these agents may pose potential health risks, such as triggering allergic reactions and affecting metabolic balance, which does not meet consumer expectations for food safety and health. Summary of the Invention

[0004] The present invention provides a method for ultra-fresh frozen storage of shrimps, which solves the above-mentioned technical problems.

[0005] The present invention solves the above-mentioned technical problems in the following ways:

[0006] A method for ultra-fresh frozen storage of shrimps comprises the following steps:

[0007] S1. Pre-processing of fresh shrimp: remove the heads, shells and shrimp threads of the fresh shrimps, and then drain until there is no moisture on the surface;

[0008] S2. Sauce preparation: Soybeans, water, yeast, and peanuts are used as raw materials. After raw material processing, soaking, steaming, cooling, inoculation, salting, fermentation, and beating, vegetable oil, sugar, and garlic are added and the sauce is simmered over low heat.

[0009] S3. Stirring and preserving: Evenly mix the pretreated shrimps with the sauce at a ratio of one pound of shrimps to one ounce of sauce, and store them in a conventional frozen state. The sauce acts as a freezing medium to wrap the shrimps, thereby inhibiting ice crystals from damaging the shrimp cells.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, in the fresh shrimp pretreatment step, the specific operation of draining the shrimp until there is no moisture on the surface is: placing the shrimp on a filter and letting it stand for 10-15 minutes, or gently absorbing the surface moisture with sterile gauze.

[0012] Furthermore, in the sauce preparation step, raw material processing includes screening soybeans and peanuts to remove impurities and moldy particles, and the mass ratio of soybeans to peanuts is 2:1 or 3:1.

[0013] Furthermore, in the sauce preparation step, the soaking conditions are as follows: the soybeans and peanuts are soaked in clean water at 20-25° C. for 8-12 hours, until the particles swell and no hard core is left.

[0014] Furthermore, in the sauce preparation step, the cooking temperature is 100-121° C. and the cooking time is 30-60 minutes, until the raw materials are cooked and softened and the protein is denatured.

[0015] Furthermore, in the sauce preparation step, the inoculation step is as follows: the raw materials after steaming are cooled to 30-35° C., and yeast strains accounting for 0.5-1% of the total mass of the raw materials are inoculated.

[0016] Furthermore, in the sauce preparation step, the salt mixing and fermentation conditions are: adding 10-15% of the total mass of the raw materials with table salt, fermenting at 25-30° C. for 7-15 days, and stirring regularly during the fermentation.

[0017] Furthermore, in the sauce preparation step, the vegetable oil added after beating is peanut oil, and the added amount is 5-10% of the total mass of the sauce; the sugar is white sugar, and the added amount is 3-5% of the total mass of the sauce; the garlic is crushed fresh garlic cloves, and the added amount is 2-4% of the total mass of the sauce.

[0018] Furthermore, the temperature of the slow fire simmering is 80-90° C., and the simmering time is 20-30 minutes, until the sauce is thick and the aroma overflows.

[0019] Furthermore, in the stirring and preserving step, the conventional freezing storage temperature is below -18°C, and the central temperature of the shrimp is maintained below -15°C during storage.

[0020] The beneficial effects of the present invention are:

[0021] The soy protein, peanut protein, and fermented polysaccharides in the sauce form a three-dimensional network that coats the surface of the shrimp cells. When the temperature drops, the macromolecular chains entangle water molecules, slowing their orderly arrangement into ice crystals. This results in smaller and more evenly distributed ice crystals, reducing the risk of mechanical penetration of cell membranes by sharp ice crystals. Furthermore, the proteins and polysaccharides adsorb onto the ice crystals, transforming them from sharp, needle-like structures into rounded particles, reducing the risk of physical damage.

[0022] The vegetable oil added to the sauce forms a continuous oil film to wrap the shrimp, reducing the diffusion of water inside the cells to the ice crystal area outside the cells, and preventing cell dehydration and shrinkage; at the same time, the flexible structure of the oil film can absorb the local pressure during ice crystal growth, reducing the possibility of cell membrane rupture.

[0023] The salt (10%-15%), sugar (3%-5%), and solutes such as amino acids and organic acids produced by fermentation in the sauce increase the colligative properties of the system after the solutes dissolve, causing the freezing point to drop significantly compared to pure water, reducing the amount of ice crystals generated during the freezing process; and the hydroxyl and amino groups of sugars and amino acids can form hydrogen bonds with water molecules, converting free water into bound water and reducing its freezing ability.

[0024] In traditional freezing, the formation of extracellular ice crystals leads to solute concentration, causing osmotic imbalance and protein denaturation. The solutes in the sauce maintain osmotic pressure balance inside and outside the cells, preventing enzyme inhibition caused by excessive intracellular ion concentrations and preventing protein aggregation and denaturation due to dehydration.

[0025] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the description, the following is a detailed description of the preferred embodiments of the present invention. The specific implementation methods of the present invention are given in detail in the following examples. DETAILED DESCRIPTION

[0026] The principles and features of the present invention are described below. The examples provided are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. The following paragraphs describe the present invention in more detail by way of example. The advantages and features of the present invention will become more apparent from the following description and claims.

[0027] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a central component. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] Example 1

[0030] A method for ultra-fresh frozen storage of shrimps comprises the following steps:

[0031] S1. Pre-treatment of fresh shrimp: Remove the head, shell, and shrimp thread of the fresh shrimp to make shrimp meat, and drain until there is no moisture on the surface. This reduces the free water content on the shrimp surface and the amount of ice crystals formed during freezing, which prevents ice crystals from piercing the cell membrane and causing nutrient loss.

[0032] S2. Sauce Preparation: Soybeans, water, yeast, and peanuts are used as raw materials. After raw material processing, soaking, steaming, cooling, inoculation, salting and fermenting, and beating, vegetable oil, sugar, and garlic are added and simmered over low heat to form a sauce. Peanut oil forms an oil film around the shrimp, blocking water migration; sugar lowers the freezing point of the system and reduces ice crystal formation; allicin exerts a natural antibacterial effect and delays oxidation and deterioration; simmering over low heat fully blends the sauce ingredients and forms a thick protective film;

[0033] S3. Stirring for preservation: Evenly mix the pre-treated shrimp with the sauce at a ratio of one ounce of sauce to one pound of shrimp. Accurately control the amount of sauce to ensure a uniform protective film is formed on the surface of the shrimp, and avoid excessive sauce affecting the taste or insufficient protection due to too little sauce. Then, perform conventional freezing for storage. The sauce acts as a freezing medium to wrap the shrimp, inhibiting the damage of ice crystals to the shrimp cells, thereby retaining more than 90% of the freshness, taste and nutritional components of the shrimp without the use of chemical water-retaining agents.

[0034] Example 2

[0035] In order to improve the standardized operation of shrimp pretreatment and ensure that there is no moisture on the surface to reduce ice crystal damage during freezing, the present invention further includes:

[0036] During the pretreatment of fresh shrimp, the specific operation of draining until there is no moisture on the surface of the shrimp is as follows: place the shrimp on a strainer and let it stand for 10-15 minutes, using gravity to drain naturally to avoid mechanical squeezing that damages the cell structure, or use sterile gauze to gently absorb the surface moisture. Aseptic operation avoids secondary contamination, and gentle blotting can prevent damage to the shrimp tissue.

[0037] Example 3

[0038] In order to optimize the process parameters for sauce preparation and improve the antifreeze protection and flavor of the sauce by regulating the raw material ratio and fermentation conditions, the present invention further includes:

[0039] In the sauce preparation steps, raw material processing includes screening soybeans and peanuts to remove impurities and moldy particles. The mass ratio of soybeans to peanuts is 2:1 or 3:1. The 2:1 ratio focuses on protein content, and the 3:1 ratio focuses on fat aroma. Both can provide sufficient carbon and nitrogen sources for yeast fermentation.

[0040] The soaking conditions are as follows: Soak soybeans and peanuts in clean water at 20-25°C for 8-12 hours, until the particles swell and there is no hard core, so that the raw materials can fully absorb water and soften, destroy the cell wall structure, promote the dissolution of protein and polysaccharides, and improve fermentation efficiency.

[0041] The cooking temperature is 100-121℃, and the cooking time is 30-60 minutes, until the raw materials are cooked and soft and the protein is denatured. High-temperature cooking moderately denatures the plant protein, making it easier for yeast to decompose it into amino acids and other umami substances, while killing the miscellaneous bacteria in the raw materials. High-pressure cooking at 121℃ can shorten the time to 30 minutes, and more thoroughly kill spores. After protein denaturation, it is easier for the protease secreted by yeast to decompose it into umami amino acids.

[0042] The inoculation steps are as follows: after the raw materials are steamed and cooled to 30-35° C., yeast strains accounting for 0.5-1% of the total weight of the raw materials are inoculated, and salt-tolerant yeasts are selected to survive in subsequent salt-mixed fermentation, preferably Saccharomyces rouxii or salt-tolerant Saccharomyces cerevisiae strains. Such strains can still ferment vigorously at a salt concentration of 10-15%, and the trehalose produced can replace water molecules to stabilize the cell membrane during freezing. Antifreeze protectants such as trehalose and glycerol are produced through the metabolism of the salt-tolerant yeast, while the growth of spoilage bacteria is inhibited.

[0043] The salt-mixing fermentation conditions are: add 10-15% of the total mass of raw materials in table salt, ferment at 25-30 ° C for 7-15 days, and stir regularly during the period. The table salt inhibits the reproduction of harmful microorganisms through osmotic pressure, and cooperates with yeast to ferment to produce organic acids, esters and other flavor substances, giving the sauce a complex umami taste.

[0044] The vegetable oil added after beating is peanut oil, and the added amount is 5-10% of the total weight of the sauce. The peanut oil forms an oil film with a thickness of 0.1-0.2 mm on the surface of the sauce to block the sublimation of water during freezing. The sugar is white sugar, and the added amount is 3-5% of the total weight of the sauce. The white sugar and salt synergistically lower the freezing point to below -5°C. The garlic is crushed fresh garlic cloves, and the added amount is 2-4% of the total weight of the sauce. The antibacterial activity of allicin can inhibit the reproduction of psychrophilic bacteria during frozen storage.

[0045] The temperature for slow cooking is 80-90℃, and the cooking time is 20-30 minutes, until the sauce is thick and the aroma overflows. Slow cooking allows the sauce ingredients to fully blend and form a thick protective film.

[0046] Example 4

[0047] In order to maintain the freshness of shrimp for a long time through the synergistic effect of temperature control and sauce, the present invention further includes:

[0048] During the stirring and preservation step, the conventional freezing storage temperature is below -18°C, and the center temperature of the shrimp is maintained below -15°C during storage. The low temperature maintains the center temperature of the shrimp ≤-15°C to inhibit microbial activity and biochemical reactions; the sauce is used as a freezing medium to wrap the shrimp, and the soy protein-polysaccharide network in the sauce physically blocks the growth of ice crystals. The polyvalent solutes (salt, sugar, amino acids) lower the freezing point to below -8°C, reducing the amount of ice crystals generated; the glycerol produced by fermentation acts as a natural antifreeze, reducing the viscosity of the system and slowing the growth rate of ice crystals. The trehalose and other components produced by fermentation stabilize the cell membrane structure. Multiple mechanisms inhibit the mechanical damage of ice crystals to cells and the solute concentration damage. Without the help of chemical water-retaining agents, more than 90% of the freshness, taste and nutritional components of the shrimp can be retained. This all-natural preservation method avoids the risk of chemical additive residues and meets clean label requirements.

[0049] Working principle:

[0050] Fresh shrimp are cooked into shells and drained until the surface is completely dry. This reduces the free water content on the shrimp surface. Free water is the primary source of ice crystal formation during freezing. Reducing the free water content reduces ice crystal formation, preventing ice crystals from piercing cell membranes and causing nutrient loss, thus paving the way for subsequent preservation steps.

[0051] The soy protein, peanut protein, and fermented polysaccharides in the sauce form a three-dimensional network that coats the surface of the shrimp cells. When the temperature drops, the macromolecular chains in this network entangle water molecules, slowing their orderly arrangement into ice crystals. This results in smaller and more evenly distributed ice crystals, reducing the risk of mechanical penetration of cell membranes by sharp ice crystals. Furthermore, proteins and polysaccharides adsorb onto the surface of the ice crystals, transforming them from sharp, needle-like structures into rounded particles, reducing the risk of physical damage.

[0052] The added vegetable oil forms a continuous film on the surface of the sauce, enveloping the shrimp. This reduces the diffusion of intracellular water into the extracellular ice crystal region, preventing cell dehydration and shrinkage. Furthermore, the flexible structure of the film absorbs the localized pressure from ice crystal growth, reducing the likelihood of cell membrane rupture.

[0053] The salt (10%-15%), sugar (3%-5%), and fermented solutes such as amino acids and organic acids in the sauce dissolve and increase the colligative properties of the system, significantly lowering the freezing point compared to pure water and reducing ice crystal formation during freezing. Furthermore, the hydroxyl and amino groups of sugars and amino acids can form hydrogen bonds with water molecules, converting free water into bound water and reducing its freezing ability. During traditional freezing, the formation of extracellular ice crystals leads to solute concentration, causing osmotic imbalance and protein denaturation. The solutes in the sauce maintain osmotic pressure balance inside and outside the cell, preventing enzyme inhibition caused by excessive intracellular ion concentration and preventing protein aggregation and denaturation due to dehydration. Allicin exerts a natural antimicrobial effect, inhibiting the growth of psychrophilic bacteria during frozen storage and slowing oxidative deterioration of shrimp. Glycerol produced by fermentation acts as a natural antifreeze, reducing the viscosity of the system and slowing the growth of ice crystals. Components such as trehalose produced by fermentation stabilize the cell membrane structure. These multiple mechanisms inhibit mechanical damage to cells caused by ice crystals and solute concentration.

[0054] The pre-treated shrimp and sauce are mixed evenly in a specific ratio to ensure a uniform protective film forms on the shrimp surface before conventional freezing. The sauce acts as a freezing medium to encapsulate the shrimp. Through the synergistic effects of these multiple mechanisms, it inhibits ice crystal damage to the shrimp cells, preserving over 90% of the shrimp's freshness, taste, and nutrients without the need for chemical water-retaining agents. This achieves all-natural preservation, avoids the risk of chemical additive residues, and meets clean label requirements.

[0055] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A method for ultra-fresh frozen storage of shrimp, characterized in that: The following steps are involved: S1. Pre-processing of fresh shrimp: remove the heads, shells and shrimp threads of the fresh shrimps, and then drain until there is no moisture on the surface; S2. Sauce preparation: Soybeans, water, yeast, and peanuts are used as raw materials. After raw material processing, soaking, steaming, cooling, inoculation, salting, fermentation, and beating, vegetable oil, sugar, and garlic are added and the sauce is simmered over low heat. S3. Stirring and preserving: Evenly mix the pretreated shrimps with the sauce at a ratio of one pound of shrimps to one ounce of sauce, and store them in a conventional frozen state. The sauce acts as a freezing medium to wrap the shrimps, thereby inhibiting ice crystals from damaging the shrimp cells.

2. The method for ultra-fresh frozen storage of shrimp according to claim 1, wherein: In the fresh shrimp pretreatment step, the specific operation of draining the shrimp until there is no moisture on the surface is: placing the shrimp on a filter and letting it stand for 10-15 minutes, or gently absorbing the surface moisture with sterile gauze.

3. The method for ultra-fresh frozen storage of shrimp according to claim 1, wherein: In the sauce preparation step, raw material processing includes screening soybeans and peanuts to remove impurities and moldy particles, and the mass ratio of soybeans to peanuts is 2:1 or 3:

1.

4. The method for ultra-fresh frozen storage of shrimp according to claim 1, wherein: In the sauce preparation step, the soaking conditions are as follows: the soybeans and peanuts are soaked in clean water at 20-25° C. for 8-12 hours until the particles swell and no hard core is left.

5. The method for ultra-fresh frozen storage of shrimp according to claim 1, characterized in that: In the sauce preparation step, the cooking temperature is 100-121° C. and the cooking time is 30-60 minutes, until the raw materials are cooked and softened and the protein is denatured.

6. The method for ultra-fresh frozen storage of shrimp according to claim 1, characterized in that: In the sauce preparation step, the inoculation step is as follows: the raw materials after steaming are cooled to 30-35° C., and yeast strains accounting for 0.5-1% of the total weight of the raw materials are inoculated.

7. The method for ultra-fresh frozen storage of shrimp according to claim 1, characterized in that: In the sauce preparation step, the salt mixing and fermentation conditions are: adding 10-15% of the total mass of the raw materials with salt, fermenting at 25-30° C. for 7-15 days, and stirring regularly during the fermentation.

8. The method for ultra-fresh frozen storage of shrimp according to claim 1, characterized in that: In the sauce preparation step, the vegetable oil added after beating is peanut oil, and the added amount is 5-10% of the total weight of the sauce; the sugar is white sugar, and the added amount is 3-5% of the total weight of the sauce; the garlic is crushed fresh garlic cloves, and the added amount is 2-4% of the total weight of the sauce.

9. The method for ultra-fresh frozen storage of shrimp according to claim 1, characterized in that: The temperature of the slow fire simmering is 80-90° C., and the simmering time is 20-30 minutes, until the sauce is thick and the aroma overflows.

10. The method for ultra-fresh frozen storage of shrimp according to claim 1, characterized in that: In the stirring and preserving step, the conventional freezing storage temperature is below -18°C, and the central temperature of the shrimp is maintained below -15°C during storage.