Fish fillet anti-freezing and water-retaining polypeptide as well as preparation method and application thereof

Abstract

The invention discloses a fillet anti-freezing and water-retaining polypeptide and a preparation method and application thereof.The preparation method comprises the steps that fish scales, residual fish meat and fat on tuna skin are removed, deionized water is added for homogenization after the tuna skin is cleaned and cut into pieces, and homogenate is obtained; performing magnetic stirring and centrifugation, taking supernatant liquid, performing centrifugation again, and drying the supernatant liquid to obtain crude protein; and adding deionized water into the crude protein to obtain a crude protein aqueous solution, carrying out enzymolysis, enzyme deactivation, pH adjustment and centrifugation, freeze-drying the supernatant, adding water to redissolve, and adjusting the concentration to 1-3 mg / mL to obtain the tuna skin anti-freezing water-retention polypeptide. The polypeptide can inhibit formation of ice crystals, reduce water loss and degradation of protein structures by the ice crystals, prevent secondary and tertiary structural changes of proteins in a freeze-thaw cycle, inhibit oxidation of myofibrillar proteins, reduce protein denaturation and fat oxidation, effectively guarantee the flavor and water binding capacity of fillets, prevent protein denaturation and improve the frozen quality of salmons.

Description

Technical Field

[0001] This invention relates to the field of antifreeze and water retention technology for aquatic products, and particularly to an antifreeze and water retention polypeptide for fish fillets, its preparation method, and its application. Background Technology

[0002] Tuna skin, a major byproduct of seafood processing, accounts for approximately 5-8% of the whole fish's weight and is currently mostly treated as waste or processed into low-value feed. However, tuna skin contains over 70% protein, and its amino acid composition is rich in glycine, proline, and hydroxyproline. Through targeted enzymatic hydrolysis, these collagen proteins can be degraded into low-molecular-weight protease hydrolysates. These hydrolysates not only retain the structural characteristics of the protein, but their exposed polar amino acid residues can also regulate ice crystal morphology by forming hydrogen bond networks with water molecules. In particular, these protease hydrolysates can adsorb onto the surface of ice crystals, inhibiting ice crystal growth through steric hindrance. Although studies have reported the activity characteristics of fish antifreeze proteins, systematic research and application of tuna skin protease hydrolysates as natural antifreeze and water-retaining agents, especially for the frozen preservation of fish fillets, are rarely reported in domestic and international literature and patent databases. This provides important evidence for the innovation of this invention.

[0003] Currently, commonly used antifreeze and water-retaining agents in industry mainly fall into two categories: one is chemically synthesized additives, represented by complex phosphates. Although these can improve the quality of frozen products by increasing the water-holding capacity of fish, long-term intake may lead to health problems such as calcium and phosphorus metabolism disorders. The EU and other regions have imposed strict restrictions on their use. In addition, related issues were exposed on this year's 315 Gala, causing consumers to have a negative attitude towards purchasing related products. Therefore, there is an urgent need to develop a green and safe antifreeze and water-retaining agent. The other category is antifreeze proteins (AFPs) or antifreeze glycoproteins (AFGPs). Although these biological antifreeze and water-retaining agents are safe and efficient, their market price is as high as several thousand US dollars per gram due to the difficulty of extraction and purification and low yield, making it difficult to achieve industrial application. Summary of the Invention

[0004] This invention provides a fish fillet antifreeze and water-retaining polypeptide, its preparation method, and its application, to overcome the above-mentioned problems.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: This invention provides a method for preparing antifreeze and water-retaining peptides for fish fillets, comprising the following steps: S1: Remove the scales and residual fish meat and fat from the tuna skin, wash and cut it into small pieces, add deionized water to homogenize, obtain a homogenate, stir magnetically and centrifuge, take the supernatant after centrifugation and centrifuge again, dry the supernatant to obtain crude protein. S2: Add deionized water to the crude protein to obtain a crude protein aqueous solution, enzymatically hydrolyze it, inactivate the enzyme, adjust the pH of the solution, centrifuge, freeze-dry the supernatant, and then reconstitute it with water to adjust the concentration to 1-3 mg / mL to obtain a fish fillet antifreeze and water-retaining polypeptide solution.

[0006] Furthermore, in S2, the crude protein aqueous solution is enzymatically hydrolyzed using pepsin, trypsin, or neutral protease.

[0007] Furthermore, in S2, the enzymatic hydrolysis conditions are as follows: When using pepsin for enzymatic hydrolysis, the temperature is 37 °C, pH 2.0, and the hydrolysis time is 5 h. When using trypsin for enzymatic hydrolysis, the temperature is 37 °C, pH 8.0, and the hydrolysis time is 5 h. When using neutral protease for enzymatic hydrolysis, the temperature is 50 °C, pH 7.0, and the hydrolysis time is 5 h.

[0008] Furthermore, in S1, during the homogenization step, the mass ratio of the tuna skin to the deionized water is 1:2-5.

[0009] Furthermore, in S2, the mass ratio of crude protein to deionized water is 1:40-60.

[0010] Furthermore, in S2, the pH of the solution is adjusted to 7 after enzyme inactivation.

[0011] Furthermore, in S1, the specific conditions for homogenization, magnetic stirring, and centrifugation are as follows: Homogenize at 800-1000 rpm for 5-10 min; stir the homogenate magnetically at 0-4 ℃ for 4-6 h; centrifuge twice at 1000 × g, 4 ℃, for 5 min.

[0012] Further, in S1, the specific steps for drying the supernatant are as follows: the supernatant after centrifugation is placed in a self-sealing bag, the air is removed, it is sealed, and it is laid flat and frozen at -20 ℃. The frozen supernatant is then freeze-dried using a vacuum freeze dryer at a temperature of -50 to -60 ℃, with the vacuum degree maintained at 10-30 Pa, and the drying time is 24-48 h.

[0013] Another aspect of the present invention provides a fish fillet antifreeze and water-retaining polypeptide, which is prepared by the method described above.

[0014] In another aspect, the present invention provides the application of the aforementioned fish fillet antifreeze and water-retaining polypeptide in fish fillet antifreeze and water-retaining, the method of application comprising the following steps: Fish fillets were soaked in a fish skin antifreeze and water-retaining peptide solution, with a mass ratio of fish fillets to pepsin hydrolysate antifreeze and water-retaining agent of 1:3. After soaking, the surface moisture was drained at 4 ℃, and the fish fillets were placed in resealable bags for packaging. The samples were stored at -20 ℃ for 24 h, and then thawed at 4 ℃ for 12 h. After repeating the freeze-thaw cycle three times, the fish fillets with antifreeze and water-retaining treatment were obtained.

[0015] The beneficial effects of this invention are: (1) In this method, antifreeze and water-retaining peptides are prepared using tuna skin. Tuna skin peptides have the ability to inhibit ice crystal formation, which can reduce the damage of ice crystals to the muscle fibers of fish fillets during freezing cycles, maintain the water-holding capacity, texture and flavor of fish meat, and make it closer to the taste of fresh fish meat. (2) This method is a food-grade enzymatic hydrolysis process, without any chemically synthesized additives, and the process is simple and relatively low in cost; (3) The tuna skin used in this method is a by-product of aquatic product processing, which can realize the high-value utilization of waste and has both environmental and economic value. (4) This method has a wide range of applications. It is not only applicable to salmon, but also to antifreeze and water retention of marine fish fillets such as tuna and sea bream. It does not affect the original flavor of the product and can mask the fishy smell, thus ensuring the quality of the fish products. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 The above are flavor radar images of salmon fillets in Examples 1-3 and Comparative Examples 1-3 of the present invention. Figure 2 These are scanning electron microscope images of salmon fillets from Examples 1-3 and Comparative Examples 1-3 of the present invention; Figure 3 The results of freeze denaturation and oxidation of myofibrils in salmon fillets in Examples 1-3 and Comparative Examples 1-3 of this invention; Figure 4 The results show the conformational results of myofibrillar proteins in salmon fillets in Examples 1-3 and Comparative Examples 1-3 of this invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example Example 1: Preparation of antifreeze and water-retaining peptides for fish fillets and methods for improving the freeze-thaw stability and water retention of fish fillets 1. A method for preparing a fish fillet antifreeze and water-retaining polypeptide solution (antifreeze and water-retaining agent), comprising the following steps: S1: Take frozen tuna skin, thaw it naturally in deionized water, remove the scales, residual fish meat and fat from the tuna skin, wash it clean with deionized water, drain the water from the surface of the skin, and cut it into pieces (or chop it). Take 30 g of the above-treated tuna skin, add 90 mL of deionized water (ratio 1:3), homogenize at 9000 rpm for 10 min, and magnetically stir the homogenate at 4 ℃ for 5 h. After magnetic stirring, centrifuge the homogenate at 1000 × g at 4 ℃ for 5 min. Take the supernatant after centrifugation and centrifuge again at 1000 × g at 4 ℃ for 5 min to obtain the supernatant. Put the supernatant into a self-sealing bag, remove the air, seal it, and freeze it flat at -20 ℃. Freeze the frozen supernatant in a vacuum freeze dryer at -50 ℃ and maintain the vacuum degree at 10-30 Pa for 24 h to obtain crude protein from tuna skin. S2: 2g of crude tuna skin protein was reconstituted with 100 mL of deionized water (the mass ratio of crude protein to deionized water was 1:50) to obtain a crude protein aqueous solution. Pepsin was added to the solution at a rate of 0.5% of the weight of the crude tuna skin protein, specifically 10 mg of pepsin for every 2g of crude tuna skin protein. The solution was hydrolyzed at 37 ℃ and pH 2.0 (crude protein aqueous solution) for 5 h. After hydrolysis, pepsin hydrolysate was obtained. The pepsin hydrolysate was placed in a resealable bag, the air was removed, and the bag was sealed. The bag was then frozen at -20 ℃. The frozen pepsin hydrolysate was then freeze-dried using a vacuum freeze dryer at -50 ℃ and a vacuum level maintained at 10-30 Pa for 48 h. After freeze-drying, the solution was dissolved in deionized water to obtain a 2 mg / mL polypeptide solution, which is the tuna skin antifreeze and water-retaining polypeptide solution.

[0020] 2. A method for improving the freeze-thaw stability and water retention of fish fillets, comprising the following steps: After slaughtering the salmon, remove the head, tail, skin, gut and remove the bones. Rinse it with clean water and drain the water from the surface of the salmon. Cut the salmon fillets into 4 cm × 1 cm × 1 cm pieces and set aside. Salmon fillets were soaked in the prepared tuna skin antifreeze and water-retaining peptide solution at 4 °C for 4 h, with a mass ratio of salmon fillets to tuna skin antifreeze and water-retaining peptide solution of 1:3. After soaking, the surface moisture was drained at 4 °C, and the fillets were packaged in resealable bags. The samples were stored at -20 °C for 24 h and then thawed at 4 °C for 12 h. This process was a freeze-thaw cycle to simulate the conditions encountered during commercial storage and transportation. After repeating the freeze-thaw cycle three times, the processed salmon fillets were obtained and labeled with pepsin.

[0021] Example 2: The only difference between this embodiment and Example 1 is that in this embodiment, trypsin is used for enzymatic hydrolysis, and the amount added is 0.5% of the weight of crude fish skin protein, of which 2 g of crude fish skin protein is added with 10 mg of trypsin. The enzymatic hydrolysis conditions are: 37 ℃, pH 8.0, and hydrolysis time of 5 h. The other steps and parameters are the same as in Example 1. The salmon fillets obtained are labeled as trypsin.

[0022] Example 3: The only difference between this embodiment and Example 1 is that, in this embodiment, neutral protease is used for enzymatic hydrolysis, and the amount added is 0.8% of the weight of crude fish skin protein, of which 2 g of crude fish skin protein is added with 0.016 g of neutral protease. The enzymatic hydrolysis conditions are: 50 ℃, pH 7.0, and hydrolysis time of 5 h. All other steps and parameters are the same as in Example 1. The obtained salmon fillets are labeled with neutral protease.

[0023] Comparative Example Comparative Example 1: The only difference between this comparative example and Example 1 is that the preparation step of the antifreeze and water-retaining peptide for fish fillets is omitted in this comparative example. Instead, the tuna skin pepsin hydrolysate is replaced with water. Otherwise, it is the same as Example 1, that is, the salmon fillets are soaked in water as a negative control group, and the salmon fillets obtained after treatment are marked as a control.

[0024] Comparative Example 2: The only difference between this comparative example and Example 1 is that in this comparative example, the salmon was slaughtered, its head and tail were removed, its skin was removed, its belly was cut open to remove the internal organs, its bones were removed, and it was washed clean with water. The surface water of the salmon was drained, and it was cut into 4 cm × 1 cm × 1 cm fillets. No antifreeze and water retention treatment was performed, which is the positive control group. The salmon fillets were marked as fresh.

[0025] Comparative Example 3: Salmon fillets treated with commercial antifreeze The only difference between this comparative example and Example 1 is that, in this comparative example, the processed and cut salmon fillets were soaked in a commercial antifreeze agent for antifreeze and water retention treatment. The commercial antifreeze agent consists of 4% sucrose + 4% potassium sorbate. Other steps and parameters are the same as in Example 1. The resulting salmon fillets are labeled as commercial antifreeze agents.

[0026] The quality and flavor of the salmon fillets treated in Examples 1-3 and Comparative Examples 1-3 were determined: 1. Testing method: (1) Texture properties determination: Texture analysis was performed using a TA-XT Plus texture analyzer (Stable Micro Systems, Godalming, UK). Each sample was analyzed 10 times.

[0027] (2) Water-holding capacity test: Thawing loss was measured by measuring the weight W1 before freezing and the weight W2 after thawing. Thawing loss (%) = ×100%; Centrifugation loss determination: 3 g fish fillets were centrifuged at 10,000 × g and 4 ℃ for 15 minutes. After centrifugation, the separated water was removed. W3 and W4 are the weights before and after centrifugation, respectively. Centrifugation loss (%) = ×100%; Cooking loss: Thawed fish samples were placed in a freezer bag and heated in a water bath until the internal temperature reached 75 ℃. W5 is the weight of the sample before cooking, and W6 is the weight of the sample after cooking. Cooking loss (%) = ×100%.

[0028] (3) Color measurement: The L* (brightness), a* (red chromaticity) and b* (yellow chromaticity) parameters were recorded using a CR-400 colorimeter (Konica Minolta, Tokyo, Japan). Each sample was measured three times at different locations, and the average value was taken to obtain the final result.

[0029] (4) Odor determination: The odor of salmon was analyzed using a PEN 3 electronic nose (Insent, Atsugi, Japan). The salmon fillet sample was placed in a 50 mL flask and sealed with plastic wrap before measurement.

[0030] (5) Microstructure: The microstructure of salmon during the freeze-thaw cycle was observed using a scanning electron microscope (SEM) (S-4800, Hitachi Ltd., Tokyo, Japan).

[0031] (6) Determination of protein oxidation degree: Extract myofibrillar protein from salmon fillets and determine the surface hydrophobicity, protein solubility, dityrosine content, thiol content, carbonyl content and Ca2+-ATPase activity of myofibrillar protein.

[0032] (7) Protein conformation determination: The fluorescence spectrum, circular dichroism spectrum and secondary structure of salmon myofibrillar protein were determined.

[0033] 2. The measurement results are as follows: (1) The changes in the textural properties of salmon fillets after freeze-thaw cycles are shown in Table 1.

[0034] Table 1. Changes in the textural properties of salmon fillets after freeze-thaw cycles.

[0035] Texture properties are an important aspect of evaluating fish meat quality, with firmness and elasticity being the most important indicators. Compared to Comparative Example 1, the firmness of Examples 1-3 was significantly improved (…). p The hardness was <0.05), while the elasticity was enhanced to varying degrees, with Example 3 showing the highest levels of both hardness and elasticity. This indicates that the antifreeze and water-retaining agents of Examples 1-3 inhibited ice crystal formation during freezing and reduced the degree of degradation of protein structures by ice crystals.

[0036] (2) The color change results of fish fillets after freeze-thaw cycles in each embodiment and comparative example are shown in Table 2.

[0037] Table 2. Color changes after freeze-thaw cycles

[0038] Note: The freezing process can affect the surface color of fish. The a* value reflects changes in myoglobin, while the b* value indicates changes in lipid composition.

[0039] As shown in Table 2, compared with Comparative Example 2, both L* and a* values ​​decreased, while b* value increased. There was no significant difference between Example 3 and the control group. During the freeze-thaw cycle, the increase in b* value was due to protein denaturation and lipid oxidation. The decrease in a* value was due to the oxidation of myoglobin in salmon at low temperatures, leading to an increase in its content. This indicates that adding the antifreeze and water-retaining agents from Examples 1-3 can reduce protein denaturation and lipid oxidation during the freeze-thaw process of fish fillets.

[0040] (3) The results of water loss of fish fillets after freeze-thaw cycles in each embodiment and comparative example are shown in Table 3.

[0041] Table 3. Results of water loss after freeze-thaw cycles

[0042] As can be seen from the data in Table 3, compared with other groups, Comparative Example 1 had significantly higher thawing and centrifugation losses. p <0.05). The reduced water-holding capacity of Comparative Example 1 may be due to the mechanical damage to muscle cells caused by the freeze-thaw cycle, which exacerbated the formation and recrystallization of ice crystals. However, the addition of antifreeze and water-retaining agents in Examples 1-3 mitigated these losses, with Example 3 showing the most significant reduction in water loss compared to Comparative Example 2. Example 3 showed no significant difference from the control group.

[0043] Figure 1 shows radar charts of the responses of 10 sensors to the volatile odors of each embodiment and comparative example. The electronic nose can be used to detect changes in volatile odors, which are mainly composed of aldehydes, ketones, and alcohols, and are key to identifying the fishy smell of salmon. W1W (inorganic sulfides), W1S (aromatic components), and W2S (alcohols) showed the highest responses. Among these three sensors, Comparative Example 1 showed the most significant response, indicating that high concentrations of sulfides, alcohols, and other compounds causing unpleasant odors are formed during freeze-thaw cycles. After adding the antifreeze and water-retaining agents of Examples 1-3 to the salmon samples, the response values ​​of these three sensors gradually decreased, indicating a reduction in unpleasant odors, demonstrating that the antifreeze and water-retaining agents prepared in this scheme can maintain the quality of the fish fillets.

[0044] Figure 2 shows scanning electron microscope (SEM) images of salmon from the various examples and comparative examples. Comparative Example 2 shows a uniform texture and a smooth surface. In contrast, Comparative Example 1 shows severe damage, with a severely damaged surface and numerous large interfiber gaps. This damage can be attributed to the destructive effect of ice crystals formed during freezing, and the increased thawing loss disrupts the network structure of the fish proteins. However, the salmon samples from Examples 1-3 treated with the antifreeze and water-retaining agent showed less surface damage, with only some obvious gaps in the muscle fibers, indicating significant cryoprotective properties. Furthermore, Example 3 showed no significant difference from the control group.

[0045] Figure 3 shows the effects of each example and comparative example on the freezing denaturation and oxidation of salmon myofibrillar protein during freeze-thaw cycles, where (a) surface hydrophobicity, (b) protein solubility, (c) total thiol content, (d) carbonyl content, (e) dimertyrosine content, and (f) Ca2+-ATPase activity. Compared with Comparative Example 1, the surface hydrophobicity of Examples 1-3 was significantly reduced, with Example 3 showing the lowest surface hydrophobicity, indicating that the antifreeze-water-retaining agent effectively inhibited the degree of protein aggregation. Compared with Comparative Example 1, the protein solubility and carbonyl content of Examples 1-3 were all reduced, while Example 3 showed no significant difference from the control group, indicating that the antifreeze-water-retaining agent prepared in this scheme effectively inhibited the degree of protein oxidation.

[0046] Figure 4 shows the effects of each example and comparative example on the conformation of salmon myofibrillar proteins during freeze-thaw cycles. (a) Fluorescence spectrum, (b) Circular dichroism spectrum, and (c) Secondary structure content. Compared to Comparative Example 1, Examples 1-3 showed a reduced λmax blue shift, decreased tryptophan polarity, and greater fluorescence intensity. Figure 4 As shown in B and C, the α-helical structure of Examples 1-3 is much higher than that of Comparative Example 1, indicating that the addition of antifreeze and water-retaining agents in Examples 1-3 can effectively prevent changes in the secondary and tertiary structures of proteins during freeze-thaw cycles and inhibit myofibrillar protein oxidation.

[0047] In summary, the antifreeze and water-retaining agent (fish fillet antifreeze and water-retaining peptide) prepared in this method inhibits ice crystal formation, effectively reduces water loss and the degree of degradation of protein structure by ice crystals. During freezing, the addition of this antifreeze and water-retaining agent effectively prevents changes in the secondary and tertiary structures of proteins during freeze-thaw cycles, inhibits myofibril protein oxidation, and also reduces protein denaturation and lipid oxidation during the freeze-thaw process of fish fillets. This effectively preserves the flavor and water-holding capacity, prevents protein denaturation, and improves the frozen quality of fish fillets / fish meat. The antifreeze and water-retaining agent provided in this method is not only suitable for salmon but also for fillets of other marine fish such as tuna and sea bream, demonstrating a wide range of applications. Furthermore, the preparation method is simple, low-cost, and enables high-value utilization of waste, combining environmental and economic value.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 a fish fillet anti-freeze water-holding polypeptide, characterized in that, The method comprises the following steps: S1: removing the fish scales and residual fish meat and fat on the tuna skin, washing, cutting, adding deionized water to homogenize, obtaining a homogenate, magnetically stirring, centrifuging, taking the supernatant after centrifugation, centrifuging again, drying the supernatant to obtain crude protein; S2: adding deionized water to the crude protein to obtain a crude protein aqueous solution, enzymatic hydrolysis, enzyme inactivation, adjusting the pH of the solution, centrifugation, freeze-drying the supernatant, re-dissolving in water, adjusting the concentration to 1-3 mg / mL, and preparing a fish slice antifreeze and water-retention polypeptide solution.

2. The method for preparing the antifreeze and water-retaining polypeptide for fish fillets according to claim 1, characterized in that, In S2, the crude protein aqueous solution is subjected to enzymatic hydrolysis using pepsin, trypsin or neutral protease.

3. The method for preparing the antifreeze and water-retaining polypeptide for fish fillets according to claim 2, characterized in that, In S2, the enzymatic hydrolysis conditions are as follows: When pepsin is used for enzymatic hydrolysis, 37 ℃, pH 2.0, and enzymatic hydrolysis time of 5 h; When trypsin is used for enzymatic hydrolysis, 37 ℃, pH 8.0, and enzymatic hydrolysis time of 5 h; When neutral protease is used for enzymatic hydrolysis, 50 ℃, pH 7.0, and enzymatic hydrolysis time of 5 h.

4. The method for preparing the antifreeze and water-retaining polypeptide for fish fillets according to claim 1, characterized in that, In S1, in the homogenization step, the mass ratio of the tuna skin to the deionized water is 1:2-5.

5. The method for preparing the antifreeze and water-retaining polypeptide for fish fillets according to claim 1, characterized in that, In S2, the mass ratio of the crude protein to deionized water is 1:40-60.

6. The method for preparing the antifreeze and water-retaining polypeptide for fish fillets according to claim 1, characterized in that, In S2, after enzyme inactivation, the pH of the solution is adjusted to 7.

7. The method for preparing the antifreeze and water-retaining polypeptide for fish fillets according to claim 1, characterized in that, In S1, the specific conditions of homogenization, magnetic stirring and centrifugation are as follows: Homogenizer 800-1000 rpm, homogenization for 5-10 min; the homogenate is magnetically stirred at 0-4 ℃ for 4-6 h; both times of centrifugation are at 1000 x g, 4 ℃, for 5 min.

8. The method for preparing the antifreeze and water-retaining polypeptide for fish fillets according to claim 1, characterized in that, In S1, the specific steps for drying the supernatant are as follows: the supernatant after centrifugation is placed in a self-sealing bag, air is discharged, the bag is sealed, and the supernatant is flat-frozen at -20 ℃, then the frozen supernatant is freeze-dried by a vacuum freeze-drying machine, the temperature is -50 to -60 ℃, the vacuum degree is maintained at 10-30 Pa, and the drying time is 24-48 h.

9. A fish fillet anti-freeze water retaining polypeptide, characterized in that, The fish slice antifreeze and water-retention polypeptide is prepared by the method for preparing the fish slice antifreeze and water-retention polypeptide according to claim 1.

10. Use of a fish fillet anti-freeze aqua-polypeptide according to claim 9 in fish fillet anti-freeze aqua-polypeptide, characterized in that, The method for use comprises the following steps: The fish slices are soaked in the fish slice antifreeze and water-retention polypeptide solution, and the mass ratio of the fish slices to the fish slice antifreeze and water-retention polypeptide solution is 1:3; after the soaking is completed, the surface water is drained, the fish slices are placed in self-sealing bags, and the bags are well sealed; the samples are stored at -20 ℃ for 24 h, then thawed at 4 ℃ for 12 h, and the above steps are repeated for three times to obtain the fish slices after antifreeze and water-retention treatment.

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