Refrigerating fluid capable of remarkably improving freezing quality of fish meat and freezing method thereof

Abstract

The invention relates to the technical field of fish meat freezing and fresh-keeping, in particular to refrigerating fluid capable of remarkably improving the fish meat freezing quality. The refrigerating fluid is prepared from the following components in percentage by mass: 10 to 15 percent of ethanol, 1 to 3 percent of chitosan, 1.0 to 2.5 percent of rhizoma polygoni cuspidati extract, 0.05 to 0.15 percent of spearmint extract, 2 to 5 percent of malic acid and the balance of deionized water. The freezing method is dipping freezing, the fish meat is dipped in a pre-cooled freezing liquid and then is subjected to cryopreservation, and the freezing temperature is-18 DEG C to-38 DEG C. The preparation method of the refrigerating fluid comprises the following steps: adding the chitosan into the malic acid and the deionized water, and uniformly stirring to obtain a solution A; sequentially adding ethanol and spearmint extract into the solution A, and stirring; and adding the polygonum cuspidatum extract, stirring and homogenizing. According to the freezing liquid, the freezing rate of fish meat can be remarkably increased, mechanical damage to muscle fibers caused by repeated formation of ice crystals is greatly reduced, the influence of temperature fluctuation on the quality of the fish meat is reduced, and the influence of freezing on the quality of the fish meat is reduced to the maximum extent.

Description

Technical Field

[0001] The invention relates to the technical field of fish meat freezing and fresh-keeping, and more specifically to a freezing liquid and a preparation method thereof for significantly improving the freezing quality of fish meat. The invention also provides a freezing method using the freezing liquid. Background Art

[0002] Freezing is the most widely used method for preserving fish. It not only inhibits the reproduction of microorganisms, but also reduces the activity of endogenous enzymes in cells, thereby extending the shelf life of fish. The freezing rate is recognized as a key factor that can affect the quality of frozen products. When the freezing rate is accelerated, the ice crystals formed will be smaller and the number will increase. These fine ice crystals can be more evenly distributed inside and outside the muscle cells, thereby significantly reducing the mechanical damage to the cells caused by the melting of ice crystals, which is beneficial to maintaining the edible and processing quality of fish. Traditional freezing methods include blast freezing, plate freezing and liquid nitrogen freezing. However, due to the complex composition and poor thermal conductivity of food, the freezing rates of the first two methods are relatively low. Although liquid nitrogen freezing is extremely fast, it requires about 0.8-2.0 kg of liquid nitrogen per kilogram of food, which consumes a lot and cannot be recycled. How to balance the freezing rate and cost investment has become an urgent problem to be solved in the field of freezing technology.

[0003] Immersion freezing technology, also known as immersion freezing or liquid quick freezing, is a rapid freezing technology. It refers to the rapid heat exchange of food materials after direct or indirect contact with the immersion freezing liquid precooled to a specific temperature, and the central temperature of the food materials is rapidly reduced to below -18°C to complete freezing. At present, immersion freezing is mainly used on fruits, vegetables, pork and large pelagic fish, but it is less used on freshwater fish, especially Xinjiang cold-water fish. The advantages of immersion freezing are fast freezing rate, low energy consumption, high quality of frozen products, the immersion freezing liquid can be recycled, and the equipment required for freezing is simple in structure. However, during the immersion freezing process, if the expansion pressure generated by the external ice layer when the inner layer of water freezes exceeds the limit of the external ice layer, the frozen product will crack. Therefore, freezing rates that are too fast or too slow will have an adverse effect on the quality of frozen food. How to reasonably control the freezing speed and better maintain the quality of frozen products when using immersion freezing technology is the focus of current research.

[0004] Immersion freezing liquid, also known as low-temperature coolant or antifreeze liquid, is a liquid medium for immersion freezing. The choice of freezing liquid is an important factor in determining the quality of frozen products. Commonly used immersion freezing liquids are mainly binary, ternary and multi-component immersion freezing liquids composed of salts, polyols, sugars and other antifreeze components. Due to the strong corrosiveness, high volatility and high viscosity of binary and ternary immersion freezing liquids, the research on multi-component compound immersion freezing liquids is becoming more and more popular.

[0005] Therefore, it is an important topic to develop a freezing liquid that is non-corrosive, has a fast freezing rate, and guarantees the quality of fish meat. Summary of the invention

[0006] In view of the above technical problems, the object of the present invention is to provide a freezing liquid that significantly improves the freezing quality of fish meat. The freezing liquid significantly increases the freezing rate of fish meat to 17.14 cm / h, and after storage, the thawing loss rate, brightness and hardness are good, thereby significantly improving the quality of frozen fish products.

[0007] The purpose of the present invention is achieved through the following technical scheme: a freezing liquid for significantly improving the freezing quality of fish meat, which is composed of the following components in mass percentage: 10-15% ethanol, 1-3% chitosan, 1.0-2.5% knotweed extract, 0.05-0.15% spearmint extract, 2-5% malic acid, and the balance is deionized water.

[0008] Preferably, ethanol is 10-12%, chitosan is 1-2%, knotweed extract is 1.0-2%, spearmint extract is 0.05-0.10%, malic acid is 3-5%, and the balance is deionized water.

[0009] Preferably, ethanol is 12%, chitosan is 2%, polygonum cuspidatum extract is 1.0%, spearmint extract is 0.10%, malic acid is 3%, and the balance is deionized water.

[0010] Preferably, the extraction method of the knotweed extract is: (1) drying and crushing Polygonum cuspidatum to obtain coarse powder; (2) extracting the crude powder with an aqueous solution of choline chloride and lactic acid to obtain an extract, wherein the mass ratio of choline chloride to lactic acid in the aqueous solution of choline chloride and lactic acid is 1:6, the water content of the aqueous solution is 8%, the liquid-to-solid ratio of the extraction is 10:1 mL / g, the extraction temperature is 40° C., and the extraction time is 40 min; (3) purifying the extract with a macroporous resin and eluting with an aqueous solution of choline chloride and lactic acid to obtain an eluate, wherein the mass ratio of choline chloride to lactic acid in the aqueous solution of choline chloride and lactic acid is 1:0.5, and the water content of the aqueous solution is 10%; (4) The eluate is purified by ultrafiltration membrane, the filtrate is concentrated, and freeze-dried to obtain a knotweed extract.

[0011] Preferably, the spearmint extract is extracted by adding 12 times the amount of water to soak, heating and boiling for 3 hours, collecting the filtrate, then adding water to 6 times the amount and boiling for 2 hours, collecting the filtrate, combining the two filtrates, concentrating them, and drying them.

[0012] Preferably, the ratio between the absolute value of the freezing point of the freezing liquid and its viscosity at -20°C is 1.19.

[0013] Preferably, the freezing method of the freezing liquid is immersion freezing, the fish meat is immersed in the pre-cooled freezing liquid and then frozen for storage, and the freezing temperature is -18°C to -38°C.

[0014] The present invention also provides a method for preparing the above-mentioned freezing liquid that significantly improves the freezing quality of fish meat, the specific steps of which are: (1) adding chitosan to malic acid and deionized water according to the formula amount and stirring evenly to obtain solution A; (2) adding ethanol and spearmint extract to solution A in sequence, stirring for 20-40 min, to obtain a mixed solution B; (3) Add the Polygonum cuspidatum extract to the mixed solution B and continue stirring until uniform and homogenous.

[0015] Preferably, the stirring time of the spearmint extract is 30 minutes.

[0016] Preferably, in step (3), after stirring, homogenization is performed using a high-speed disperser at a speed of 3000-15000 rpm for 1-5 minutes.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The freezing liquid of the present invention can significantly improve the freezing rate of fish meat, greatly reduce the mechanical damage to muscle fibers caused by repeated formation of ice crystals, reduce the impact of temperature fluctuations on the quality of fish meat, and minimize the impact of freezing on the color, hardness, protein solubility and oxidation degree of fish meat. The ratio of the absolute value of the freezing point to the viscosity at -20°C is used as a solution stability index to obtain a freezing liquid formula suitable for immersion freezing below -36°C. The ratio between the absolute value of the freezing point and the viscosity at -20°C reaches 1.19, showing that the immersion freezing liquid has excellent stability and is very suitable for various freezing applications.

[0018] The freezing liquid of the present invention contains a Polygonum cuspidatum extract, the main components of which are resveratrol and rhamnolide, which are both an antioxidant and a food stabilizer, and can maintain the freshness and nutritional value of food. In addition, resveratrol can also protect cell structure, and resveratrol has a protective effect on the protective membrane, which can reduce the rupture and damage of the cell membrane during the freezing process, thereby ensuring the integrity and activity of the cell. The inventor believes that this is a key factor in weakening the mechanical damage to muscle fibers caused by repeated formation of ice crystals and protecting the quality of fish. Spearmint extract can inhibit bacteria, molds and yeasts, etc., and maintain the freshness of food. Spearmint extract can also react with an appropriate amount of chitosan to generate active ingredients such as reticular chitosan microspheres coated with resveratrol, ensuring that resveratrol continues to play a role in a stable manner. Malic acid and rhamnolide, as pH regulators, can maintain a suitable acid-base balance, and play a vital role in maintaining the quality of fish. At the same time, malic acid can also improve the solubility and dispersibility of chitosan in the entire system, and help to form a high-quality freezing liquid.

[0019] 2. Compared with traditional freezing liquid and freezing methods, the immersion freezing of the present invention can minimize the impact of freezing on the color, hardness, protein solubility and oxidation degree of fish meat, and can also maintain the quality of fish meat in freeze-thaw cycles within 3 times. At the same time, the use of food-grade raw materials can also reduce the corrosion to equipment, promote the economic development prospects of cold-water fish resources, and provide more options for the frozen storage and preservation of cold-water fish.

[0020] 3. The method for preparing the freezing liquid that significantly improves the freezing quality of fish meat of the present invention meets the current national requirements for low-carbon environmental protection and the principle of green chemical process. No harmful waste is generated in the production process. The obtained impregnation freezing liquid can be recycled and is suitable for various cold-water fish. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The effects of freezing by immersion freezing in the freezing liquid of Example 1 of the present invention and Comparative Example 2 on the thawing loss rate of northern pike during frozen storage; Figure 2 The effect of freezing by immersion freezing of the freezing liquid of Example 2 of the present invention and Comparative Example 2 on the color of the fish meat of northern pike during frozen storage; Figure 3 The effects of freezing by immersion freezing in the freezing liquid of Example 3 of the present invention and Comparative Example 1 on the hardness of northern pike meat during frozen storage. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described in detail below in conjunction with specific implementation methods, but does not constitute any limitation to the present invention.

[0023] The method for determining the freezing point in the present invention is as follows: the prepared immersion freezing liquid is placed in a low-temperature resistant glass sample bottle, one end of a K-type thermocouple probe is connected to a multi-channel temperature recorder, and the other end is fixed at a distance of 1 cm from the bottom of the glass sample bottle. The glass sample bottle containing the freezing liquid is placed in an ultra-low temperature device for freezing, and the temperature recorder is turned on to record data every 10 seconds. Wait for the immersion freezing liquid to be completely frozen and stop recording, and a curve of the freezing liquid temperature changing with time can be obtained, and the average value of the smooth part of the curve is used as the approximate freezing point of the solution. If the temperature-time curve does not have a smooth stage, but a peak and a trough appear, it means that the solution has been supercooled, and the temperature of the peak is used as the approximate freezing point of the solution.

[0024] The viscosity was determined using an Anton Paar MCR 302e rotational rheometer with a coaxial cylindrical fixture set and a shear rate range of 0.1-100 s -1 The viscosity of the solution was measured at -20 °C and the shear rate was 10 s -1 The viscosity at this time is the viscosity of the immersion freezing liquid.

[0025] The freezing liquid composition of the present invention uses the ratio of the absolute value of the freezing point of the freezing liquid to the viscosity at -20°C as an evaluation index to determine the range of each component and compound it. The ratio between the absolute value of the freezing point and the viscosity at -20°C reaches 1.19, indicating the excellent stability of the immersion freezing liquid.

[0026] The white pike raw material described in the embodiment of the present invention can be purchased from aquatic product markets in some areas of Xinjiang, such as Altay, Urumqi, Shihezi and other areas.

[0027] The -36°C mentioned in the examples is to simulate factory freezing temperatures.

[0028] The 4°C is intended to simulate the refrigeration temperature of fresh fish in the market, which is close to actual application.

[0029] The -18°C temperature indicates that the fish block has been fully frozen and has achieved the desired freezing effect.

[0030] Example 1 The raw materials are obtained according to the formula of 10% ethanol, 3% chitosan, 2.5% knotweed extract, 0.15% spearmint extract, 5% malic acid and 79.35% deionized water; chitosan is added to malic acid and deionized water and stirred evenly to obtain solution A; ethanol and spearmint extract are added to solution A in sequence, stirred for 30 minutes, to obtain a mixed solution B; knotweed extract is added to the mixed solution B and continued to stir evenly, and homogenized with a high-speed disperser at a speed of 3000-15000rmp for 1-5 minutes.

[0031] Example 2 The raw materials are obtained according to the formula of 15% ethanol, 1% chitosan, 1% knotweed extract, 0.05% spearmint extract, 2% malic acid, and 80.95% deionized water; chitosan is added to malic acid and deionized water and stirred evenly to obtain solution A; ethanol and spearmint extract are added to solution A in sequence and stirred for 40 minutes to obtain mixed solution B; knotweed extract is added to mixed solution B and continued to stir evenly, and homogenized with a high-speed disperser at a speed of 15000rmp for 1-5 minutes. .

[0032] Example 3 The difference from Example 2 is that the content of ethanol is 12%, chitosan is 2%, the content of Polygonum cuspidatum extract is 1.0%, the content of spearmint extract is 0.10%, the content of malic acid is 3%, and the content of deionized water is 81.9%.

[0033] Comparative Example 1 According to the formula: 12% ethanol, 1.0% Polygonum cuspidatum extract, 3% malic acid, and 84% deionized water. Mix the ethanol, Polygonum cuspidatum extract, malic acid and deionized water, stir evenly, and then use a high-speed disperser to homogenize at a speed of 3000-15000rmp for 1-5 minutes.

[0034] Comparative Example 2 According to the formula: 12% ethanol, 2% chitosan, 0.10% spearmint extract, 3% malic acid, and 82.9% deionized water. Mix the ethanol, chitosan, spearmint extract, malic acid, and deionized water, reduce the mixture to half and homogenize with a high-speed disperser at 3000-15000 rpm for 1-5 minutes.

[0035] Experimental example The fish processing methods involved in the experimental example are: Fresh white pike were stunned and slaughtered, and then the scales, internal organs, head and skin were removed. The back muscles were cut into small pieces (2×2×1 cm3) and all were individually vacuum-packed and stored in a 4°C refrigerator to pre-cool the core temperature to 0-4°C for later use.

[0036] Control freezing (RF) group: the fish blocks were immersed in the control freezing liquid precooled to -24±1.0℃ and -36±1.0℃, and taken out immediately when the center temperature of the fish blocks reached -18℃, and marked as RF-24 and RF-36 respectively; Experimental freezing (IF) group: The fish blocks were immersed in the immersion freezing solution precooled to -24±1.0℃ and -36±1.0℃, and taken out immediately when the center temperature of the fish blocks reached -18℃, and marked as IF-24 and IF-36.

[0037] All samples were stored in a -18°C refrigerator and samples were taken for measurement on the 1st, 7th, 14th, 21st and 28th days. Except for scanning electron microscopy, all other indicators were measured after being thawed in a 4°C refrigerator until the central temperature was between 0-4°C.

[0038] 1. Freezing parameters and freezing rates of northern pike using cryostat Comparative freezing (RF) group: the fish pieces were immersed in the freezing liquid of Comparative Example 2 which was pre-cooled to -24±1.0℃ and -36±1.0℃, and taken out immediately when the center temperature of the fish pieces reached -18℃, and were marked as RF-24 and RF-36 respectively; Experimental freezing (IF) group: The fish blocks were immersed in the freezing solution of Example 1 precooled to -24±1.0°C and -36±1.0°C, and taken out immediately when the center temperature of the fish blocks reached -18°C, and marked as IF-24 and IF-36.

[0039] First, insert the probe of the temperature recorder precisely into the geometric center of the fish block to ensure that the recorded temperature data can accurately reflect the temperature changes inside the fish block. Set the time interval of the temperature recording point to 10 seconds so that the temperature change process can be captured in detail. After the freezing begins, the temperature recorder begins to record the changes in the center temperature of the fish block at the set time interval until the center temperature of the fish block drops to -18°C. Freezing rate V calculation formula: Where L is the shortest distance from the surface of the fish block to its temperature center / cm, and t is the time required for the center temperature of the fish block to drop to 10°C below the freezing point of the fish meat after the surface reaches 0°C / h. The freezing parameters and freezing rates of northern pike frozen by different freezing methods are shown in Table 1.

[0040] Table 1 Freezing parameters and freezing rates for freezing northern pike Freezing method Medium temperature / ℃ Phase change time / s Total time / s Freezing rate / (cm / h) RF-24 -24±1 3600 9740 0.53 IF-24 -24±1 120 760 7.20 RF-36 -36±1 2530 4060 1.10 IF-36 -36±1 70 410 17.14 It can be clearly seen from Table 1 that the freezing rate of the freezing liquid IF-36 of Example 1 is significantly better than that of other groups, because the heat exchange efficiency of the liquid freezing medium is high, which improves the convective heat exchange rate between the frozen material and the freezing medium. The control group did not add the knotweed extract, and the freezing rate was significantly lower than that of the experimental group, indicating that the various components of the freezing liquid of the present invention play a good promoting role, and the effective ingredients resveratrol and rhein in the knotweed extract can play a synergistic role with other components to improve the freezing efficiency of the freezing liquid.

[0041] 2. Effect of freezing liquid on thawing loss rate of northern pike during frozen storage After thawing, weigh the total weight of the packaged fish pieces of the four groups of RF-24, RF-36, IF-24, and IF-36 (m1), the weight of the vacuum bag (m2), and the weight of the fish meat after removing the vacuum bag and absorbing the moisture on the surface of the fish meat with filter paper (m3); calculate the thawing loss rate of each group respectively, the formula is as follows: The changes of thawing loss rate of each group over time are shown as follows Figure 1 .

[0042] Thawing loss rate is an important indicator to measure the water retention capacity and quality of frozen food. An increase in thawing loss rate will affect the appearance of the product and reduce consumer acceptance; it may also cause a loss of total weight and water-soluble nutrients, thereby reducing economic value. Figure 1 As shown in the figure, over time, the loss rates of the IF-36 and IF-24 groups were lower than those of the RF-36 and RF-24 groups. At the same temperature, the loss rates of the RF-36 and RF-24 groups were higher. The thawing loss rate of fish meat treated by immersion freezing at -36°C was always lower than that of the other three groups of samples. The reason is that the freezing rate of the IF-36 group was the fastest, and the formation rate of ice crystals was faster than the diffusion rate of water, resulting in the formation of small ice crystals that could be evenly distributed inside and outside the cells, causing minimal mechanical damage to the fish tissue during thawing. The freezing solution in the RF-36 and RF-24 groups did not contain Polygonum cuspidatum extract, which also shows that resveratrol can protect the cell structure. Resveratrol has a protective effect on the protective membrane, which can reduce the rupture and damage of the cell membrane during freezing, thereby ensuring the integrity and activity of the cells. This is also a key factor in reducing the mechanical damage to muscle fibers caused by repeated formation of ice crystals and protecting the quality of fish meat.

[0043] 3. Effect of freezing liquid on the color of northern pike during frozen storage Comparative freezing (RF) group: the fish pieces were immersed in the freezing liquid of Comparative Example 2 which was pre-cooled to -24±1.0℃ and -36±1.0℃, and taken out immediately when the center temperature of the fish pieces reached -18℃, and were marked as RF-24 and RF-36 respectively; Experimental freezing (IF) group: The fish blocks were immersed in the immersion freezing solution of Example 2 which was precooled to -24±1.0°C and -36±1.0°C, and were taken out immediately when the center temperature of the fish blocks reached -18°C, and were marked as IF-24 and IF-36.

[0044] Thaw (2 × 2 × 1 cm) was measured using a calibrated handheld colorimeter. 3 ) The L* and b* of fish meat were measured three times and the average value was taken. * represents brightness, b * Represents the yellow-blue degree, and the color change of northern pike meat during freezing is obtained as follows Figure 2 As shown. Figure 2 As shown in (A), after 28 days of frozen storage, the brightness of IF-24 and IF-36 samples is still lower than that of RF-24 and RF-36. * The change in the value is mainly due to protein oxidation during frozen storage. The stability of meat color is deeply affected by storage temperature. As the storage time increases, sample b * The values ​​increased, indicating that freeze-thaw cycles had an adverse effect on the color stability of northern pike samples, e.g. Figure 2 (B) shows that IF-36 * The value was obviously lower than that of other groups. This indicates that under the same freezing conditions, IF-24 and IF-36 immersion freezing methods are more conducive to the preservation of northern pike. This also verifies that resveratrol is a key factor in reducing the damage to fish quality during freezing.

[0045] 4. Effect of freezing liquid on the hardness of northern pike meat during frozen storage Comparative freezing (RF) group: the fish pieces were immersed in the freezing liquid of comparative example 1 which was precooled to -24±1.0℃ and -36±1.0℃, and taken out immediately when the center temperature of the fish pieces reached -18℃, and were marked as RF-24 and RF-36 respectively; Experimental freezing (IF) group: The fish blocks were immersed in the immersion freezing solution of Example 3 which was precooled to -24±1.0°C and -36±1.0°C, and were taken out immediately when the center temperature of the fish blocks reached -18°C. The fish blocks were marked as IF-24 and IF-36.

[0046] The P / 50 probe of the TA-XT-plus texture analyzer was used to perform two compression tests on the thawed fish meat to determine its hardness. The measurement parameters were set as follows: the rate was 1.0 mm / s during the test and the trigger force was 5.0 g. The ambient temperature was maintained between 18-24°C during the test. Figure 3 shown.

[0047] like Figure 3As shown in the figure, due to the increase in muscle shear resistance and protein denaturation caused by changes in protein conformation and myogenicity, the hardness of all samples showed a gradual downward trend with the extension of storage time, among which the downward trend of the IF-36 group was significantly lower than that of other groups, indicating that the faster the immersion freezing speed, the less mechanical damage to muscle cells and protein denaturation caused by ice crystals can be minimized, which can effectively alleviate the deterioration of the texture of the white pike meat during frozen storage, and is more beneficial to the quality of the white pike meat during cold storage. Protein conformational changes and myogenic changes can lead to changes in the hardness and texture of the fish meat. At the same temperature, the fish meat of the IF group had better hardness and good quality; while the RF group did not add spearmint extract and chitosan, and its fish meat hardness and quality decreased significantly. It can be seen that spearmint extract and chitosan play a good role in promoting the function of each component of the freezing solution.

[0048] In summary, the present invention significantly improves the freezing rate of white pike meat, greatly reduces the mechanical damage to muscle fibers caused by repeated formation of ice crystals, and minimizes the effect of freezing on the color and hardness of white pike meat. The problem of short shelf life and long-term preservation of white pike is solved, which promotes the economic development prospects of cold-water fish resources and provides more options for cold-water fish in terms of frozen storage and preservation.

[0049] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A freezing liquid that significantly improves the freezing quality of fish meat, characterized in that: The invention is composed of the following components in percentage by mass: 10-15% ethanol, 1-3% chitosan, 1.0-2.5% knotweed extract, 0.05-0.15% spearmint extract, 2-5% malic acid, and the balance is deionized water.

2. The freezing liquid for significantly improving the freezing quality of fish meat according to claim 1, characterized in that: Ethanol 10-12%, chitosan 1-2%, knotweed extract 1.0-2%, spearmint extract 0.05-0.10%, malic acid 3-5%, and the balance is deionized water.

3. The freezing liquid for significantly improving the freezing quality of fish meat according to claim 2, characterized in that: Ethanol 12%, chitosan 2%, Polygonum cuspidatum extract 1.0%, Spearmint extract 0.10%, malic acid 3%, and the balance is deionized water.

4. A freezing liquid for significantly improving the freezing quality of fish meat according to claim 1, 2 or 3, characterized in that: The ratio between the absolute value of the freezing point of the freezing liquid and its viscosity at -20°C is 1.

19.

5. The freezing liquid for significantly improving the freezing quality of fish meat according to claim 1, characterized in that: The freezing method of the freezing liquid is immersion freezing, and the fish meat is immersed in the pre-cooled freezing liquid and then frozen and stored, and the freezing temperature is -18°C to -38°C.

6. A method for preparing a freezing liquid for significantly improving the freezing quality of fish meat according to any one of claims 1 to 3, characterized in that: The steps include: (1) adding chitosan to malic acid and deionized water according to the formula amount and stirring evenly to obtain solution A; (2) adding ethanol and spearmint extract to solution A in sequence, stirring for 20-40 min, to obtain a mixed solution B; (3) Add the Polygonum cuspidatum extract to the mixed solution B and continue stirring until uniform and homogenous.

7. The method for preparing a freezing liquid for significantly improving the freezing quality of fish meat according to claim 6, characterized in that: The stirring time of the spearmint extract is 30 minutes.

8. The method for preparing a freezing liquid for significantly improving the freezing quality of fish meat according to claim 6, characterized in that: In the step (3), after stirring, the mixture is homogenized with a high-speed disperser at a speed of 3000-15000 rpm for 1-5 minutes.

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