A method of inhibiting the cold gelling of egg yolk with the addition of an antifreeze protein

Abstract

The application belongs to the technical field of agricultural product processing and storage, and provides a method for inhibiting gelation of ice egg yolk by adding antifreeze protein to inhibit the gelation phenomenon of ice egg yolk and improve the functional properties of ice egg yolk. The product uses antifreeze protein to perform cryoprotection on egg yolk, inhibits the cold denaturation of egg yolk protein, improves the fluidity of frozen-thawed egg yolk, and also can put the antifreeze protein into the market to expand the application range, so that more convenient and safe ice egg yolk can be used in large quantities.

Description

Technical Field

[0001] This invention relates to a method for inhibiting the freezing and gelation of egg yolks by adding antifreeze proteins, belonging to the field of agricultural product processing and storage technology. Background Technology

[0002] my country has a high egg production, but egg product processing is insufficient. Frozen eggs are one of the deep-processed egg products, with advantages such as long shelf life and ease of storage. With the development of modern technology, more and more frozen egg yolks are being used in various foods, such as cakes, salad dressings, and mayonnaise. Studies have shown that the quality of frozen egg yolks added to food is no different from that of fresh egg yolks. Frozen egg yolks also have higher food safety performance, are more convenient due to the elimination of the separation step, and are easier to transport and store, thus having a broad market. However, egg yolks gel during freezing. The internal viscosity of frozen egg yolks increases and their fluidity decreases due to low-temperature freezing, leading to a decline in quality and limiting their application in enterprises. Therefore, how to effectively inhibit gelation of egg yolks during frozen storage has become an urgent technical problem to be solved.

[0003] Currently, antifreeze agents are commonly added to egg yolks to maintain their quality. Common antifreeze agents on the market include sugars, complex phosphates, polyphenols, and protein hydrolysates; however, these agents are difficult to widely market due to price and availability issues. In contrast, antifreeze proteins are widely accepted due to their abundant sources and lower sweetness. Therefore, this invention uses the method of adding antifreeze proteins to improve the flowability of frozen-thawed egg yolks. Since antifreeze proteins have a good inhibitory effect on gelation of frozen egg yolks, they can also be marketed, expanding their application and making frozen egg yolks more convenient and safer to use in large quantities. This method is simple and easy to implement, and has a certain degree of innovation; therefore, the inventors have filed this application. Summary of the Invention

[0004] 1. This invention provides a method for inhibiting the freezing and gelation of egg yolks by adding antifreeze protein, thereby reducing the degree of freezing and gelation of egg yolks by treating them with antifreeze protein.

[0005] The technical solution of the present invention is as follows:

[0006] (1) Separation of egg yolk: Take fresh eggs, wash them, crack the shells, separate the egg white and the yolk, puncture the yolk membrane, collect the yolk, and stir at 300-400 r / min for 15-20 min to mix well, so as to obtain fresh and uniform egg yolk liquid.

[0007] (2) Pasteurize the uniform egg yolk liquid obtained in step (1) at 63.5℃ for 120s.

[0008] (3) Add the pasteurized egg yolk liquid obtained in step (2) to different concentrations of antifreeze protein and mix evenly at 300-400 r / min.

[0009] (4) Place the egg yolk liquid obtained in step (3) above into a -18±2℃ freezer for different times to prepare frozen egg yolks.

[0010] (5) Take out the frozen egg yolks obtained in step (4) above, thaw them at room temperature, and weigh them to obtain the finished product.

[0011] 2. The method for inhibiting the freezing and gelation of egg yolk by adding antifreeze protein according to claim 1, characterized in that the antifreeze protein used in step (3) is Anfei Bio antifreeze protein, and the amount added is 1%-5%.

[0012] 3. The method for inhibiting frozen gelation of egg yolk by adding antifreeze protein according to claim 1, characterized in that the freezing time in step (4) is 1-7 days.

[0013] Analytical methods

[0014] Viscoelasticity determination: using HAAKE TM MARS TM A rotational rheometer with a P35 rotor, a plate diameter of 35 mm, and a plate spacing of 0.3 mm was used. The sample was evenly spread on the plate, and excess was scraped off. The viscoelasticity of the sample was measured using the frequency scanning mode in oscillation mode. Parameter settings: temperature 25℃, oscillation frequency range 0.1–15 Hz. Changes in elastic modulus (G') and loss modulus (G”) were measured.

[0015] Flowability determination: The instrument settings and rotor / plate spacing selection are the same as in 1.1. The continuous scanning mode in the rotation mode is used to determine the sample's flowability. The sample is evenly spread on the plate, and excess is scraped off. The measurement parameters are set as follows: temperature 25℃, shear rate range 0.1-100s. -1 .

[0016] Particle size determination: Take 1g of each egg yolk sample, dilute it with 100mL of deionized water (1:100), and stir thoroughly with a magnetic stirrer. Perform particle size analysis using a laser particle size analyzer. Parameter settings: Measurement temperature 25℃, observation angle 90°, refractive index 1.330.

[0017] Turbidity determination: Prepare a 10% NaCl solution and set aside. Take 1g of each egg yolk sample, dilute it with 100mL of NaCl solution, and stir well with a magnetic stirrer. Place the diluted solution in a cuvette and measure the absorbance of the diluted sample at a wavelength of 660nm using a UV 2600 ultraviolet spectrophotometer, and record the result.

[0018] Zeta potential determination: Take 1g of each egg yolk sample, dilute it with 100mL of deionized water, and stir thoroughly with a magnetic stirrer. Transfer the sample supernatant to a nanoparticle size potentiometer to measure the zeta potential of the sample. Attached Figure Description

[0019] Table 1. Fitting values ​​of frozen egg yolk model at different concentrations of antifreeze protein.

[0020]

[0021] Table 1 shows a comparison of the model fitting values ​​of frozen egg yolks with different concentrations of antifreeze protein. As can be seen from Table 1, the blank group sample had the highest K value. When the proportion of antifreeze protein added increased, the K value gradually decreased, with the lowest value only slightly higher than that of fresh egg yolks. The trend of the n value was exactly the opposite of the trend of the K value. Therefore, it can be inferred that the addition of antifreeze protein can reduce the degree of aggregation between molecular chains, thereby reducing the viscosity of the sample.

[0022] Figure 1 A comparative graph showing the effect of different concentrations of antifreeze protein on the frequency scanning of frozen egg yolks.

[0023] Depend on Figure 1 It can be seen that the G″ values ​​of fresh egg yolks and frozen-thawed egg yolks with 5% added antifreeze protein both exceeded the G′ values, indicating that their viscous behavior was greater than their elastic behavior, making them viscous dominant substances. This may be because freezing causes water in the blank group egg yolks to turn into ice crystals, promoting protein denaturation and aggregation to form a gel network structure. The aggregation of egg yolk proteins after freezing forms a physical gel, which is more complex than the gel formed by intermolecular interactions. Therefore, the addition of antifreeze protein can inhibit the formation of gel networks, thereby improving the fluidity of frozen-thawed egg yolks. Further research is needed on the degree of cross-linking of frozen-thawed egg yolk proteins.

[0024] Figure 2 A comparative graph showing the effect of different concentrations of antifreeze protein on the apparent viscosity of frozen egg yolks.

[0025] Depend on Figure 2 It can be seen that the blank group samples have a higher apparent viscosity at the initial shear rate, while the apparent viscosity of the samples with added antifreeze protein is significantly reduced, indicating that the antifreeze protein inhibits the gelation of frozen egg yolks to varying degrees. (0.1-10s) -1 Within the low shear rate range, the apparent viscosity of the egg yolk sample decreases rapidly. With increasing shear rate, the apparent viscosity decreases within the range of 10-100 s⁻¹. -1 The changes within the range gradually stabilize, which is consistent with typical shear-thinning behavior, indicating that egg yolk is a pseudoplastic fluid.

[0026] Figure 3 A comparative graph showing the effect of different antifreeze protein concentrations on the particle size of egg yolk cryogels.

[0027] Depend on Figure 3 As can be seen, all sample curves exhibit a bimodal distribution. The fresh egg yolks had the smallest average particle size, followed by the sample with 5% antifreeze protein, while the blank group had the largest average particle size. This indicates that the average particle size of the frozen egg yolks treated with antifreeze protein decreased, suggesting a reduction in protein particle aggregation during the freezing process. Studies have shown that sucrose can stabilize protein molecules by covering proteins and trapping water molecules, preventing protein stretching and reducing their solubility, thus inhibiting protein particle aggregation. Antifreeze proteins may have a similar mechanism to sucrose.

[0028] Figure 4 A comparative graph showing the effect of different concentrations of antifreeze protein on the potential of egg yolk cryogels.

[0029] Depend on Figure 4 As can be seen, the blank group had the highest potential, indicating that freezing disrupted the protein structure, exposing charged groups, increasing the degree of protein cross-linking and aggregation, attracting more negative charges, and increasing the electrostatic repulsion between proteins, leading to an increase in the absolute value of the zeta potential and the formation of a stable gel structure. The addition of antifreeze proteins lowered the potential value of frozen-thawed egg yolks. This may be because the antifreeze proteins regulate ice crystal growth and prevent ice recrystallization, effectively mitigating the destructive force of ice crystals on the protein network. Therefore, it can be inferred that antifreeze proteins make the structure of frozen-thawed egg yolks more stable.

[0030] Figure 5 A comparative graph showing the effect of different antifreeze protein concentrations on the turbidity of egg yolk cryogels.

[0031] Depend on Figure 5 It can be seen that when stored at -18℃, the turbidity of egg yolks increased significantly compared to fresh egg yolks after freeze-thaw cycles, indicating significant gelation after thawing. As the concentration of antifreeze proteins increased, the turbidity of the egg yolks decreased. These results suggest that freezing-induced damage to the egg yolk leads to molecular aggregation, forming larger aggregates, while the addition of antifreeze proteins effectively reduces freezing damage and hinders molecular aggregation. Studies have shown that components in egg yolks such as LDL, HDL, and lipoproteins interact through slow freezing to form large, insoluble aggregates, thus increasing turbidity after freezing. During freezing, antifreeze proteins act on the ice-water interface system, slowing the rate of small ice crystal aggregation, resulting in smaller and more uniform ice crystals in the solution system. This slows down or prevents recrystallization in the ice-water system, effectively reducing ice crystal damage to cells, minimizing dehydration of proteins and other solids in the egg yolk, and effectively preventing protein denaturation and gelation caused by rearrangement of the egg yolk protein structure.

[0032] The good effects achieved by this invention are:

[0033] (1) This invention provides a method for inhibiting frozen gelation of egg yolks by adding antifreeze protein. By treating egg yolks with antifreeze protein, the gelation phenomenon of egg yolks under freezing and storage conditions is alleviated, the original fluidity of fresh egg yolks is maintained to a great extent, the shelf life of egg yolks is extended, and the application of frozen egg yolks in the food industry is expanded.

[0034] (2) This invention helps to solve the problem of frozen gelation of egg yolks, prolongs the storage time of liquid egg yolks and prevents them from spoiling; at the same time, it reduces their gel strength and improves their fluidity, making them easier to mix with other food ingredients during processing; the antifreeze protein series of antifreeze agents can replace traditional antifreeze agents, realizing consumers' pursuit of healthy and green food.

[0035] (3) The antifreeze protein studied in this invention better solves the problems of high cost, difficulty in extraction and poor molecular stability. At the same time, it reduces the cost of use for food companies while ensuring product quality, and has high commercial value. Detailed Implementation

[0036] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0037] Example 1

[0038] (1) Separation of egg yolk: Take a fresh egg, wash it, crack the shell, separate the egg white and the egg yolk, discard the egg white, place the egg yolk on absorbent paper and roll it back and forth to remove excess egg white, puncture the yolk membrane and collect the egg yolk liquid.

[0039] (2) The egg yolk liquid collected in step (1) is stirred for 15 minutes at a speed of 350 r / min using an electric mixer.

[0040] (3) The egg yolk liquid obtained in step (2) is sterilized in a constant temperature chamber at 63.2℃ for 3 minutes.

[0041] (4) Cool the sterilized egg yolk liquid obtained in step (3) to room temperature naturally.

[0042] (5) Add 3% antifreeze protein to the egg yolk liquid collected in step (4).

[0043] (6) The egg yolk liquid obtained in step (5) is stirred evenly for 10 minutes at a speed of 300 r / min using an electric mixer. (7) The frozen egg yolk liquid obtained in step (6) is stored in a -18℃ refrigerator for 7 days.

[0044] (8) Quickly remove the frozen egg yolk liquid obtained in step (7) and thaw it at room temperature for 3 hours.

Claims

1. A method for inhibiting the freezing and gelation of egg yolks by incorporating antifreeze proteins, characterized in that... The egg yolks are prepared according to the following steps: (1) Separation of egg yolk: Take fresh eggs, wash them, crack the shells, separate the egg white and the yolk, puncture the yolk membrane, collect the yolk, and stir at 300-400 r / min for 15-20 min to mix well, so as to obtain fresh and uniform egg yolk liquid. (2) Pasteurize the uniform egg yolk liquid obtained in step (1) at 63.5℃ for 120s. (3) Add the pasteurized egg yolk liquid obtained in step (2) to different concentrations of antifreeze protein and mix evenly at 300-400 r / min. (4) Place the egg yolk liquid obtained in step (3) above into a -18±2℃ freezer for different times to prepare frozen egg yolks. (5) Take out the frozen egg yolks obtained in step (4) above, thaw them at room temperature, and weigh them to obtain the finished product.

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