A phosphorus-free frozen storage water-retaining agent for tilapia fillets and its preparation method and application

Abstract

The invention relates to the field of food technology, and discloses a phosphorus-free frozen water-retaining agent for tilapia fillets, and a preparation method and application thereof. A phosphorus-free frozen water-retaining agent for tilapia fillets is composed of the following substances in mass fractions: 0.3-0.7% sorbitol, 0.1-0.5% sodium citrate, 0.5%-1.3% soy protein isolate, and the rest is distilled water. The preparation method of the phosphorus-free frozen water-retaining agent is to take sorbitol, sodium citrate, and soy protein isolate in a container respectively, add distilled water, stir and dissolve to obtain. The phosphorus-free frozen storage method of tilapia fillets is to take the tilapia fillets and soak them in the water-retaining agent solution for 0.5-1.5 hours, take them out and vacuum pack them, and then quickly put them into a -20°C environment for frozen storage. The phosphorus-free frozen water-retaining agent of the present invention can not only inhibit the denaturation of protein and fat of tilapia during frozen storage, maintain the stability of fish fillet protein, but also improve the texture characteristics of the fish fillets, and improve the antifreeze and water retention.

Description

Technical Field

[0001] The invention relates to the technical field of food, and more specifically to a phosphorus-free frozen storage water-retaining agent for tilapia fillets, and a preparation method and application thereof. Background Art

[0002] Fish is high in protein and is particularly prone to spoilage. Frozen storage is the most common way to store it. However, frozen storage will cause drying and thawing losses, which not only reduce nutrition and taste, but also cause considerable economic losses to merchants. For users, the quality loss after thawing and cooking is large, which will also reduce their confidence in buying food again. Therefore, various frozen water retainers have been continuously developed, but most of the water retainer formulas contain phosphorus. Excessive intake of phosphorus in the diet is harmful to the body, and the increase of phosphorus in the environment will cause many environmental problems.

[0003] The prior art discloses a sodium-free water-retaining agent for frozen tilapia fillets and a method thereof. The components and mass ratio of the sodium-free water-retaining agent for frozen tilapia fillets are: 45-60 parts of potassium pyrophosphate, 15-30 parts of potassium carbonate, 5-15 parts of trehalose, and 15-30 parts of potassium chloride. The method of using the water-retaining agent comprises four main steps: raw material processing, preparation of the water-retaining agent, soaking, and refrigeration. The solution mainly solves the water retention of tilapia fillets during the soaking process, maintains the natural color of the fillets, and improves the yellowing and drying phenomenon during storage.

[0004] The prior art discloses a phosphorus-free water-retaining agent for peeled squid and a method for using the same. The proportion of the components by mass is: 10-20 parts of sodium citrate; 10-20 parts of tea polyphenols; 5-10 parts of sodium D-isoascorbate; 30-35 parts of sorbitol; and 25-30 parts of lactitol. The use steps include processing squid, preparing a water-retaining agent solution, soaking the peeled squid, and freezing and preserving the squid. The solution mainly solves the water retention of the peeled squid during the soaking process, and can effectively inhibit the oxidation of squid fat and the corruption and deterioration of fish products. However, there is a significant difference in the meat quality of squid and tilapia, and the solution is not suitable for tilapia fillets.

[0005] The prior art discloses a frozen surimi compound water retaining agent and its preparation method and application, belonging to the technical field of aquatic product processing. The present invention firstly takes carrageenan oligosaccharide solution and soybean egg gelatin, cholesterol, and 1% Tween 80 to prepare carrageenan oligosaccharide liposomes by dynamic high-pressure microjetting; then, 0.3-0.7% carrageenan oligosaccharide nanoliposomes, 0.4-0.8% soybean protein isolate, 0.5-1.2% sodium caseinate, 0.2-0.7% sucrose ester, 0.3-0.6% maltodextrin, and 0.3-1% sodium diacetate are added to the surimi mass as a matrix, and mixed through secondary dynamic high-pressure microjetting to prepare a water retaining agent with a uniform state. The water retaining agent of this scheme is applied to the processing of frozen surimi, but there is an essential difference between surimi and fish fillet, and the water retaining agent of frozen surimi cannot be applied to fish fillet.

[0006] In summary, the disadvantages of the prior art include the potential impact of phosphorus in water retaining agents on the human body and the environment, and the failure to solve the problems of protein and fat denaturation, aging of fillet texture, poor antifreeze and water retention during frozen storage of tilapia. In addition, when processing fillets, there are problems such as low weight gain rate during soaking, poor water holding capacity during freezing, poor chewiness, elasticity and adhesiveness of fillets after thawing, and high loss rate after thawing relative to fresh fillets, thawing loss rate and cooking loss rate. Summary of the invention

[0007] The present invention is to overcome the above-mentioned defects of the prior art and provide a phosphorus-free frozen storage water-retaining agent for tilapia fillets.

[0008] Another object of the present invention is to provide a method for preparing a phosphorus-free frozen storage water-retaining agent for tilapia fillets.

[0009] Another object of the present invention is to provide the application of phosphorus-free frozen storage water-retaining agent for tilapia fillets.

[0010] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0011] A phosphorus-free frozen storage water-retaining agent for tilapia fillets, comprising the following substances in different mass fractions:

[0012] Sorbitol 0.3~0.7%,

[0013] Sodium citrate 0.1~0.5%,

[0014] Soy protein isolate 0.5% to 1.3%,

[0015] The rest is distilled water.

[0016] Preferably, the phosphorus-free frozen storage water-retaining agent for tilapia fillets is composed of the following substances in mass fractions:

[0017] Sorbitol 0.5%,

[0018] Sodium citrate 0.3%,

[0019] Soy protein isolate 1%,

[0020] The rest is distilled water.

[0021] Preferably, the phosphorus-free frozen storage water-retaining agent for tilapia fillets is composed of the following substances in mass fractions:

[0022] Sorbitol 0.3%,

[0023] Sodium citrate 0.5%,

[0024] Soy protein isolate 1.3%,

[0025] The rest is distilled water.

[0026] Preferably, the phosphorus-free frozen storage water-retaining agent for tilapia fillets is composed of the following substances in mass fractions:

[0027] Sorbitol 0.7%,

[0028] Sodium citrate 0.1%,

[0029] Soy protein isolate 0.5%,

[0030] The rest is distilled water.

[0031] A method for preparing the phosphorus-free frozen storage water retaining agent for tilapia fillets comprises the following steps: taking sorbitol, sodium citrate and soy protein isolate into a container respectively, adding distilled water and stirring to dissolve the obtained water retaining agent.

[0032] A method for phosphorus-free frozen storage of tilapia fillets is disclosed, which adopts the water retaining agent to carry out phosphorus-free frozen storage of tilapia fillets.

[0033] Preferably, the phosphorus-free frozen storage method of tilapia fillets comprises soaking the tilapia fillets in the water retaining agent solution for 0.5 to 1.5 hours, taking them out, vacuum packaging them, and then quickly freezing them in a -20°C environment.

[0034] Further preferably, the method for phosphorus-free frozen storage of tilapia fillets comprises the following steps:

[0035] Step 1. Slaughter healthy fresh tilapia weighing 0.75-1kg, remove the head and tail, internal organs and fish scales, wash and take the fish fillets on both sides of the spine;

[0036] Step 2. Take sorbitol, sodium citrate and soy protein isolate in a container respectively, add distilled water and stir to dissolve, so as to obtain the water retaining agent;

[0037] Step 3. Soak the fish fillets processed in step 1 in the water retaining agent prepared in step 2 for 0.5 to 1.5 hours, take them out, vacuum pack them, and then quickly freeze them in a -20°C environment.

[0038] Preferably, the size of the fish fillet in step 1 is (2-4 cm)×(0.5-1.5 cm)×(0.5-1 cm).

[0039] Preferably, the temperature of the fish fillet soaking in the water retaining agent is 4-15°C.

[0040] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0041] The phosphorus-free frozen storage water-retaining agent of the present invention can not only inhibit the denaturation of protein and fat of tilapia during frozen storage and maintain the stability of fish fillet protein, but also improve the texture characteristics of the fish fillet and enhance the freezing resistance and water retention.

[0042] The formula of the invention is a commonly used and inexpensive food additive compound formula that is optimized, which improves the soaking weight gain rate of fresh tilapia, the water holding capacity after frozen storage, chewiness, elasticity and adhesiveness, reduces the thawing loss rate, the loss rate after thawing relative to fresh fish fillets and the cooking loss rate, and improves the sales quality of tilapia.

[0043] The phosphorus-free frozen storage water-retaining agent of the present invention has excellent water-retaining capacity, can effectively reduce the dry loss of tilapia fillets during frozen storage, can improve the water-retaining capacity of the fillets after soaking, can significantly improve the water-retaining capacity after thawing and cooking, improve the texture characteristics after thawing and cooking, and enhance the chewing feeling of the fillets.

[0044] The phosphorus-free frozen storage water retaining agent effective additive of the present invention can improve the water retention of fish fillets, promote the redistribution of water in the muscle tissue of fish fillets, increase the ratio of semi-bound water, greatly improve the water retention of protein, and the gel properties of soy protein isolate and sodium citrate reduce muscle damage, freezing denaturation and dry loss during the freezing process, thereby improving the frozen storage quality of fish fillets and effectively extending the shelf life of fish fillets.

[0045] The phosphorus-free frozen water retaining agent of the present invention is phosphorus-free and environmentally friendly, the three substances in the formula are easily available, safe and inexpensive, and the preparation of the water retaining agent solution is also simple and easy to operate. While maintaining product quality and flavor, it also ensures the health of consumers. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The figures are the results of the soaking weight gain rate of each embodiment and comparative example;

[0047] Figure 2 The thawing loss rate results of various embodiments and comparative examples are shown below;

[0048] Figure 3 The loss rate results of each embodiment and comparative example after thawing relative to fresh fish fillet;

[0049] Figure 4 The water holding capacity results of various embodiments and comparative examples;

[0050] Figure 5 The cooking loss rate results of various embodiments and comparative examples are shown in FIG.

[0051] Figure 6 The chewability results of various embodiments and comparative examples are shown below;

[0052] Figure 7 The elasticity results of various embodiments and comparative examples;

[0053] Figure 8 The following are the adhesiveness results of various embodiments and comparative examples. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention is clearly and completely described below. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The raw materials used in the following examples and comparative examples are all commercially available.

[0056] A phosphorus-free frozen storage water-retaining agent for tilapia fillets, comprising the following substances in different mass fractions:

[0057] Sorbitol 0.3~0.7%,

[0058] Sodium citrate 0.1~0.5%,

[0059] Soy protein isolate 0.5% to 1.3%,

[0060] The rest is distilled water.

[0061] The preparation method of the phosphorus-free frozen storage water retaining agent for tilapia fillets comprises the following steps: taking sorbitol, sodium citrate and soy protein isolate into a container respectively, adding distilled water and stirring to dissolve the mixture.

[0062] The method for freezing and storing tilapia fillets without phosphorus comprises the following steps:

[0063] Step 1. Slaughter healthy fresh tilapia weighing 0.75-1kg / piece, remove the head, tail, internal organs and fish scales, wash and take the fish fillets on both sides of the spine. The size of the fish fillets is (2-4cm)×(0.5-1.5cm)×(0.5-1cm). ;

[0064] Step 2. Take sorbitol, sodium citrate and soy protein isolate in a container respectively, add distilled water and stir to dissolve, so as to obtain the water retaining agent;

[0065] Step 3. Soak the fish fillets processed in step 1 in the water retaining agent prepared in step 2 at a soaking temperature of 4 to 15° C. for 0.5 to 1.5 hours, take them out, vacuum pack them, and then quickly freeze them in a -20° C. environment.

[0066] Sorbitol, also known as glucitol, is a sugar alcohol that can be metabolized slowly by humans. It has a similar structure to monosaccharides and has the nutritional advantages of polyols. It is low in caloric value and sugar. It is hygroscopic, not easily used by common pathogenic bacteria, not easily oxidized, and can prevent the denaturation of carotenoids, fats, and proteins. It is a common sweetener, moisturizer, and preservative in food, daily chemicals, and medicine.

[0067] Sodium citrate, also known as sodium citrate, is derived from food, is safe and reliable, and does not cause damage to the human body. The Food and Agriculture Organization of the United Nations and the World Health Organization do not limit its daily dosage. It is a common food additive, such as a food emulsifier, flavoring agent, stabilizer, preservative, thickener, gelling agent and sweetener.

[0068] Soy protein isolate is a protein powder with a protein content of more than 90% obtained by processing soybean meal. Its structure and properties can basically replace pure soy protein. It contains nearly 20 kinds of amino acids and does not contain cholesterol. When used as a food additive, it has good emulsification, water retention, oil absorption and gelation. Adding it to meat products can improve the texture, increase the flavor and increase the protein content. As a safe antifreeze agent, soy protein isolate can effectively control the growth of ice crystals and inhibit the occurrence of recrystallization, thereby improving the quality of low-temperature cold chain food and reducing the loss of nutritional components. Soy protein isolate is a surfactant that can reduce the surface tension of water and oil, as well as the surface tension of water and air. Along its peptide chain skeleton, soy protein isolate contains many polar groups, so it has water absorption, water retention and expansion. The water absorption capacity of soy protein isolate is much stronger than that of concentrated protein, and it is almost unaffected by temperature. Therefore, soy protein isolate has the ability to retain moisture during processing.

[0069] Example 1

[0070] A phosphorus-free frozen storage water-retaining agent for tilapia fillets, comprising the following substances in different mass fractions:

[0071] Sorbitol 0.5%,

[0072] Sodium citrate 0.3%,

[0073] Soy protein isolate 1%,

[0074] The rest is distilled water.

[0075] The preparation method of the phosphorus-free frozen storage water retaining agent for tilapia fillets comprises the following steps: taking sorbitol, sodium citrate and soy protein isolate into a container respectively, adding distilled water and stirring to dissolve the mixture.

[0076] The method for freezing and storing tilapia fillets without phosphorus comprises the following steps:

[0077] Step 1. Slaughter healthy fresh tilapia weighing 0.75-1kg / piece, remove the head, tail, internal organs and fish scales, wash and take the fish fillets on both sides of the spine. The size of the fish fillets is (2-4cm)×(0.5-1.5cm)×(0.5-1cm). ;

[0078] Step 2. Take sorbitol, sodium citrate and soy protein isolate in a container respectively, add distilled water and stir to dissolve, so as to obtain the water retaining agent;

[0079] Step 3. Soak the fish fillets processed in step 1 in the water retaining agent prepared in step 2 at a soaking temperature of 15° C. for 1 hour, take them out, vacuum pack them, and then quickly freeze them in a -20° C. environment.

[0080] Example 2

[0081] A phosphorus-free frozen storage water-retaining agent for tilapia fillets, comprising the following substances in different mass fractions:

[0082] Sorbitol 0.3%,

[0083] Sodium citrate 0.5%,

[0084] Soy protein isolate 1.3%,

[0085] The rest is distilled water.

[0086] The preparation method of the phosphorus-free frozen storage water retaining agent for tilapia fillets comprises the following steps: taking sorbitol, sodium citrate and soy protein isolate into a container respectively, adding distilled water and stirring to dissolve the mixture.

[0087] The method for freezing and storing tilapia fillets without phosphorus comprises the following steps:

[0088] Step 1. Slaughter healthy fresh tilapia weighing 0.75-1kg / piece, remove the head, tail, internal organs and fish scales, wash and take the fish fillets on both sides of the spine. The size of the fish fillets is (2-4cm)×(0.5-1.5cm)×(0.5-1cm). ;

[0089] Step 2. Take sorbitol, sodium citrate and soy protein isolate in a container respectively, add distilled water and stir to dissolve, so as to obtain the water retaining agent;

[0090] Step 3. Soak the fish fillets processed in step 1 in the water retaining agent prepared in step 2 at a soaking temperature of 4° C. for 0.5 hours. Take them out, vacuum pack them, and then quickly freeze them in a -20° C. environment.

[0091] Example 3

[0092] A phosphorus-free frozen storage water-retaining agent for tilapia fillets, comprising the following substances in different mass fractions:

[0093] Sorbitol 0.7%,

[0094] Sodium citrate 0.1%,

[0095] Soy protein isolate 0.5%,

[0096] The rest is distilled water.

[0097] The preparation method of the phosphorus-free frozen storage water retaining agent for tilapia fillets comprises the following steps: taking sorbitol, sodium citrate and soy protein isolate into a container respectively, adding distilled water and stirring to dissolve the mixture.

[0098] The method for freezing and storing tilapia fillets without phosphorus comprises the following steps:

[0099] Step 1. Slaughter healthy fresh tilapia weighing 0.75-1kg / piece, remove the head, tail, internal organs and fish scales, wash and take the fish fillets on both sides of the spine. The size of the fish fillets is (2-4cm)×(0.5-1.5cm)×(0.5-1cm). ;

[0100] Step 2. Take sorbitol, sodium citrate and soy protein isolate in a container respectively, add distilled water and stir to dissolve, so as to obtain the water retaining agent;

[0101] Step 3. Soak the fish fillets processed in step 1 in the water retaining agent prepared in step 2 at a soaking temperature of 10° C. for 1.5 hours. Take them out, vacuum pack them, and then quickly freeze them in a -20° C. environment.

[0102] Comparative Examples 1 to 6

[0103] The formulas and preparation methods of the phosphorus-free frozen storage water-retaining agents for tilapia fillets of Comparative Examples 1 to 6, as well as the phosphorus-free frozen storage methods for tilapia fillets, are similar to those of Example 1, except that the differences are shown in Table 1:

[0104] Table 1 Schemes of Comparative Examples 1 to 6

[0105] Sorbitol / % Sodium citrate / % Soy protein isolate / % Comparative Example 1 0.1 0.3 1 Comparative Example 2 1 0.3 1 Comparative Example 3 0.5 0 1 Comparative Example 4 0.5 0.7 1 Comparative Example 5 0.5 0.3 0.3 Comparative Example 6 0.5 0.3 1.5

[0106] Comparative Example 7

[0107] A phosphorus-free frozen storage water-retaining agent for tilapia fillets, comprising the following substances in different mass fractions:

[0108] Sorbitol 0.64%,

[0109] Sodium citrate 0.4%,

[0110] Tea polyphenols 0.24%

[0111] Sodium D-isoascorbate 0.12%

[0112] Lactitol 0.6%

[0113] The rest is distilled water.

[0114] The preparation method of the phosphorus-free frozen storage water retaining agent for tilapia fillets comprises the following steps: taking sorbitol, sodium citrate, tea polyphenols, sodium D-isoascorbate and lactitol into a container respectively, adding distilled water and stirring to dissolve the mixture.

[0115] The method for freezing and storing tilapia fillets without phosphorus comprises the following steps:

[0116] Step 1. Slaughter healthy fresh tilapia weighing 0.75-1kg / piece, remove the head, tail, internal organs and fish scales, wash and take the fish fillets on both sides of the spine. The size of the fish fillets is (2-4cm)×(0.5-1.5cm)×(0.5-1cm). ;

[0117] Step 2. Take sorbitol, sodium citrate, tea polyphenols, sodium D-isoascorbate and lactitol in a container respectively, add distilled water and stir to dissolve, so as to obtain the water retaining agent;

[0118] Step 3. Soak the fish fillets processed in step 1 in the water retaining agent prepared in step 2 at a soaking temperature of 15° C. for 0.5 to 1.5 hours, take them out, vacuum pack them, and then quickly freeze them in a -20° C. environment.

[0119] Comparative Example 8

[0120] A phosphorus-free frozen storage water-retaining agent for tilapia fillets, comprising the following substances in different mass fractions:

[0121] Sorbitol 0.5%,

[0122] Sodium citrate 0.3%,

[0123] Soy protein isolate 1%,

[0124] Trehalose 1%

[0125] Lactitol 0.5%

[0126] The rest is distilled water.

[0127] The preparation method of the phosphorus-free frozen storage water retaining agent for tilapia fillets comprises the following steps: taking sorbitol, sodium citrate, isolated soy protein, trehalose and lactitol into a container respectively, adding distilled water and stirring to dissolve the mixture.

[0128] The method for freezing and storing tilapia fillets without phosphorus comprises the following steps:

[0129] Step 1. Slaughter healthy fresh tilapia weighing 0.75-1kg / piece, remove the head, tail, internal organs and fish scales, wash and take the fish fillets on both sides of the spine. The size of the fish fillets is (2-4cm)×(0.5-1.5cm)×(0.5-1cm). ;

[0130] Step 2. Take sorbitol, sodium citrate, soy protein isolate, trehalose and lactitol respectively in a container, add distilled water and stir to dissolve, so as to obtain the water retaining agent;

[0131] Step 3. Soak the fish fillets processed in step 1 in the water retaining agent prepared in step 2 at a soaking temperature of 15° C. for 0.5 to 1.5 hours, take them out, vacuum pack them, and then quickly freeze them in a -20° C. environment.

[0132] Comparative Example 9

[0133] A phosphorus-free frozen storage water-retaining agent for tilapia fillets, comprising the following substances in different mass fractions:

[0134] Trehalose 0.3%

[0135] Potassium pyrophosphate 1.2%

[0136] Potassium carbonate 0.7%

[0137] Potassium chloride 0.7%

[0138] The rest is distilled water.

[0139] The preparation method of the phosphorus-free frozen storage water retaining agent for tilapia fillets comprises the following steps: taking trehalose, potassium pyrophosphate, potassium carbonate and potassium chloride into a container respectively, adding distilled water and stirring to dissolve the mixture.

[0140] The method for freezing and storing tilapia fillets without phosphorus comprises the following steps:

[0141] Step 1. Slaughter healthy fresh tilapia weighing 0.75-1kg / piece, remove the head, tail, internal organs and fish scales, wash and take the fish fillets on both sides of the spine. The size of the fish fillets is (2-4cm)×(0.5-1.5cm)×(0.5-1cm). ;

[0142] Step 2. Take trehalose, potassium pyrophosphate, potassium carbonate and potassium chloride respectively in a container, add distilled water and stir to dissolve, so as to obtain the water retaining agent;

[0143] Step 3. Soak the fish fillets processed in step 1 in the water retaining agent prepared in step 2 at a soaking temperature of 15° C. for 0.5 to 1.5 hours, take them out, vacuum pack them, and then quickly freeze them in a -20° C. environment.

[0144] Effect testing and evaluation

[0145] Take fresh tilapia, kill it, remove the skin, bones and internal organs, take the muscles on both sides and cut them into blocks of about 20g, load them with weight m0, soak them in the additive solution for one hour, take them out and weigh m1, vacuum pack them and put them in a -20 degree refrigerator to freeze for 48 hours, then take them out and weigh the weight after freezing m2, then thaw them in running water for 30 minutes, wipe off the surface moisture, and weigh the weight after thawing m3.

[0146] Each experiment was repeated three times.

[0147] Experimental and computational methods:

[0148] 1. Determination of the soaking weight gain rate W1: Weigh the mass m0 of fresh tilapia fillets, soak them in the water retaining agent solution, take them out after one hour and weigh the mass m1. The soaking weight gain rate is calculated as follows:

[0149]

[0150] W is the soaking weight gain rate, m0 is the mass of the fish fillet before soaking (g), and m1 is the mass of the fish fillet after soaking (g)

[0151] 2. Determination of thawing loss rate W2: After soaking, vacuum pack the tilapia fillets and put them into the freezer of a refrigerator at -20 degrees Celsius. Take them out after freezing for 48 hours, weigh the frozen mass m2, thaw them in running water for 30 minutes, wipe off the surface moisture, and weigh the mass m3. The calculation formula for thawing loss is as follows:

[0152]

[0153] 3. Calculation of the mass loss W3 of the thawed fish fillet relative to the mass loss of the fresh fish fillet: Because the difference between the mass of the thawed fish fillet and the mass of the fresh fish fillet is an important indicator for testing the performance of the water retaining agent, it can be reflected that the water retaining agent is also very important.

[0154]

[0155] 4. Determination of water-holding capacity (WHC): According to the method of Lakshmanan et al.

[69] , accurately weigh 10g of minced fish meat, wrap it with double-layer filter paper, put it into a large centrifuge tube, put the centrifuge tube into a centrifuge, set it to 3000r / min, 10 degrees, centrifuge for 10 minutes, take out and weigh the weight of the fish meat m4. The water holding capacity is calculated as follows:

[0156]

[0157] 5. Determination of cooking loss W4: Put the thawed tilapia fillets (mass m3) into a cooking bag and cook in boiling water for 2 minutes. When the fillets are cooked, take them out and wipe dry. Weigh the mass m5 after cooking. The calculation method of cooking loss is as follows:

[0158]

[0159] Chewing, elasticity and stickiness were measured using the TMS-Pro texture analyzer from FTC, USA. The size of the sample was 10cm×5cm×5cm. The instrument was set with the following measurement parameters: the force sensor was set to 1000N, the probe was raised to 12mm from the sample surface, the deformation was 50%, the detection speed was 60mm / min, and the starting force was 0.5N. Three different positions were measured for each sample, and the measurement was repeated 3 times.

[0160] Effect test results:

[0161] The experimental results are shown in Table 2.

[0162] Table 2 Effect test results

[0163]

[0164] As can be seen from Table 2, within the concentration range of the present invention, each test index of the embodiment is better than the comparative case. Comparative cases 1 to 6 are designed according to this formula, but the values ​​are not within the formula range. The various indicators are not as good as the optimized embodiments, but the values ​​are close. Comparative Example 7 is a phosphorus-free water-retaining agent formula in the literature. All indicators are not as good as the present invention, and there are more ingredients. The tea polyphenols are also relatively expensive. When treating tilapia, a fish with a light taste, it will leave the taste of tea, which reduces the taste of tilapia. Comparative Example 8 is based on this formula and adds two common water-retaining agents on the market, trehalose and lactitol. The added water-retaining agent does not improve the water-retaining performance of the fish fillet, but rather reduces it. This shows that the more types of water-retaining agents added, the better. Comparative Example 9 is a phosphorus-containing water-retaining agent formula, and the water holding capacity, cooking loss, chewiness, elasticity and viscosity are also lower than the present invention.

[0165] The implementation methods of the present invention are not limited to the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A phosphorus-free frozen storage water-retaining agent for tilapia fillets, characterized in that: It is composed of the following substances by mass fraction: Sorbitol 0.3~0.7%, Sodium citrate 0.1~0.5%, Soy protein isolate 0.5% to 1.3%, The rest is distilled water.

2. The phosphorus-free frozen storage water-retaining agent for tilapia fillets according to claim 1, characterized in that: It is composed of the following substances by mass fraction: Sorbitol 0.5%, Sodium citrate 0.3%, Soy protein isolate 1%, The rest is distilled water.

3. The phosphorus-free frozen storage water-retaining agent for tilapia fillets according to claim 1, characterized in that: It is composed of the following substances by mass fraction: Sorbitol 0.3%, Sodium citrate 0.5%, Soy protein isolate 1.3%, The rest is distilled water.

4. The phosphorus-free frozen storage water-retaining agent for tilapia fillets according to claim 1, characterized in that: It is composed of the following substances by mass fraction: Sorbitol 0.7%, Sodium citrate 0.1%, Soy protein isolate 0.5%, The rest is distilled water.

5. The method for preparing the phosphorus-free frozen water-retaining agent for tilapia fillets according to any one of claims 1 to 4, characterized in that: Take sorbitol, sodium citrate and soy protein isolate in containers respectively, add distilled water and stir to dissolve.

6. A method for phosphorus-free frozen storage of tilapia fillets, characterized in that: The water retaining agent according to any one of claims 1 to 4 is used for phosphorus-free frozen storage of tilapia fillets.

7. The method for freezing and storing tilapia fillets without phosphorus according to claim 6, characterized in that: Soak the tilapia fillets in the water retaining agent solution for 0.5 to 1.5 hours, take them out, vacuum pack them, and then quickly freeze them in a -20°C environment.

8. The method for phosphorus-free frozen storage of tilapia fillets according to claim 7, characterized in that: The following steps are involved: Step 1. Slaughter healthy fresh tilapia weighing 0.75-1kg, remove the head and tail, internal organs and fish scales, wash and take the fish fillets on both sides of the spine; Step 2. Take sorbitol, sodium citrate and soy protein isolate respectively in a container, add distilled water and stir to dissolve, so as to obtain the water retaining agent according to any one of claims 1 to 4; Step 3. Soak the fish fillets processed in step 1 in the water retaining agent prepared in step 2 for 0.5 to 1.5 hours, take them out, vacuum pack them, and then quickly freeze them in a -20°C environment.

9. The method for phosphorus-free frozen storage of tilapia fillets according to claim 8, characterized in that: The size of the fish fillet in step 1 is (2-4 cm)×(0.5-1.5 cm)×(0.5-1 cm).

10. The method for phosphorus-free frozen storage of tilapia fillets according to claim 8, characterized in that: The temperature for soaking the fish fillets in the water-retaining agent is 4-15°C.

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