A double gel anti-freezing agent, its preparation method and application for enhancing the freeze-thaw quality of minced fish products

Abstract

The application discloses a double-gel anti-freezing agent, a preparation method thereof and application of the double-gel anti-freezing agent in enhancing the freeze-thaw quality of surimi products. The double-gel anti-freezing agent is obtained by mixing a double-network hierarchical hydrogel and a network interpenetrating self-assembled reinforced oil gel, high-speed shearing and emulsification and then cooling. The hydrogel is formed by crosslinking low-ester pectin and xanthan gum in water through Ca 2+ , Fe 3+ , and the oil gel is formed by using DHA algal oil as an oil phase and compounding enzymatic ethyl cellulose and monoglyceride. The double-gel anti-freezing agent has the functions of binding free water and limiting water migration of the water-phase gel and the functions of hydrophobic barrier and inhibiting ice crystal coarsening of the oil-phase gel, and the double-gel anti-freezing agent can reduce the loss of juice during the freeze-thaw cycle of the surimi product, inhibit the growth of ice crystals, relieve the protein oxidation of the freeze-thaw surimi product and improve the gel strength, and thus the freeze-thaw quality of the surimi product is improved.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a dual-gel antifreeze agent and its preparation method, as well as its application in enhancing the freeze-thaw quality of surimi products. Background Technology

[0002] Fish intestines, fish balls, and other surimi products are high-protein, low-fat gel foods made from surimi with myofibrillar protein as the main structural basis. They are produced by chopping, mixing, heating, and gelling, and are characterized by good elasticity and ease of consumption. Because surimi products are prone to quality deterioration, freezing or frozen storage is used to extend shelf life and meet transportation, storage, and sales requirements. However, during freezing and repeated freeze-thaw cycles, free water and weakly bound water in the surimi gel system are prone to recrystallization and ice crystal coarsening. The growth of ice crystals causes mechanical damage to the network structure of the surimi gel, severely affecting the quality of frozen surimi products.

[0003] Currently, commonly used freeze-thaw protection methods in surimi products include sucrose, sorbitol, and phosphates. However, sucrose and sorbitol can easily lead to excessive sweetness and increased calories, while the use of phosphates is limited by relevant regulations and consumer acceptance. With the increasing demand for lipid fortification, emulsions and emulsion gels are considered as a type of structured filler. Although conventional emulsification systems can improve the gel filling state, they are prone to oil droplet aggregation and precipitation or interfacial instability during freeze-thaw cycles, making it difficult to continuously form a stable barrier in the surimi protein gel network. Therefore, developing a composite freeze-thaw protection system that combines hydrophilic water-binding and hydrophobic barrier effects and can be stably dispersed in the surimi gel network is a key direction for improving the quality stability of frozen surimi products.

[0004] Based on this, the present invention proposes a dual-gel antifreeze-thaw stabilization system for surimi products. This dual-gel system is composed of a hydrogel and an olegel, possessing both hydrophilic and hydrophobic networks. The hydrogel is composed of a low-ester pectin / xanthan gum compound, which undergoes sequential Ca2+ processing. 2+ and Fe 3+ Cross-linking constructs a dual-network hierarchical structure, enhancing free water binding capacity through polysaccharide chain entanglement and ionic cross-linking. During thawing, it binds free water, blocks water molecule migration channels, and prevents juice loss. The oleogel phase uses DHA algal oil as the oil phase, employing enzymatically hydrolyzed ethyl cellulose and monoglycerides to construct an interpenetrating self-assembly network, improving oil retention and structural stability. During freezing, it competes for ice crystal growth channels through hydrophobic interactions, inhibiting ice crystal growth and coarsening. Adding the above hydrogel and oleogel to the surimi after homogenization and emulsification to form a dual-gel system can inhibit ice crystal growth and coarsening, water migration, and protein oxidation, thereby protecting the freeze-thaw quality of surimi products. Summary of the Invention

[0005] To address the problems of gel network damage and protein oxidation caused by ice crystal growth and coarsening during the freezing and repeated freeze-thaw cycles of surimi products, this invention provides a dual-gel antifreeze agent, its preparation method, and its application in enhancing the freeze-thaw quality of surimi products.

[0006] The dual-gel antifreeze agent of this invention comprises: an ionically cross-linked dual-network hydrogel and a network interpenetrating self-assembled reinforced olegel. It is formulated with low-ester pectin / xanthan gum and subjected to sequential Ca... 2+ and Fe 3+ Cross-linking forms a dual-network hydrogel; DHA algal oil is used as the oil phase and enzymatically hydrolyzed ethyl cellulose / monoglyceride is used to construct a network interpenetrating self-assembled reinforced oleogel; the hydrogel and oleogel are emulsified by high-speed shearing to form a dual-gel system, which is then applied to the freeze-thaw quality protection of surimi products.

[0007] This dual-gel system can be stably dispersed and filled in a surimi gel network, achieving the following respectively: (1) During the thawing process, the hydrogel component in the double gel prevents the loss of juice from the surimi product by binding free water and blocking the migration channels of water molecules. (2) During the freezing process, the oleogel component in the double gel competes for ice crystal channels through hydrophobic interaction and inhibits ice crystal growth, thereby improving the quality stability of surimi products during freezing or repeated freeze-thaw cycles.

[0008] The technical solution of the present invention is as follows: A bigel antifreeze agent is obtained by mixing a bi-network hierarchical hydrogel and a network interpenetrating self-assembled reinforced oleogel, followed by high-speed shear emulsification and cooling. The aforementioned dual-network hierarchical hydrogel is made by dissolving low-ester pectin and xanthan gum in water, and then using Ca... 2+ Fe 3+ Formed by sequential cross-linking; The network interpenetrating self-assembly enhanced oleogel is formed by using DHA algal oil as the oil phase and compounding it with enzymatically hydrolyzed ethyl cellulose and monoglycerides.

[0009] The preparation method of the dual-gel antifreeze agent of the present invention includes: (1) Preparation of a dual-network hierarchical hydrogel: Dissolve low-ester pectin and xanthan gum in water, and first add calcium lactate (Ca 2+ A solution was used to crosslink low-ester pectin at 30-60 °C for 1 h to form the first network layer; then ferric citrate (Fe) was added. 3+ The xanthan gum was crosslinked with a solution at 30-60 °C for 1 h to form a second network, resulting in a double-network hierarchical hydrogel. Specifically, low-ester pectin and xanthan gum are added to water and stirred at 70 °C for 20 min to ensure complete dissolution; the resulting aqueous solution preferably contains 0.5-2.0% by mass of low-ester pectin and 0.5-2.5% by mass of xanthan gum. The preferred concentration of the calcium lactate solution is 1.0 mol / L; the amount of calcium lactate solution added is 0.1% to 1% based on the total mass of the hydrogel system. The preferred concentration of the ferric citrate solution is 0.5 mol / L; the amount of ferric citrate solution added is 0.1% to 1% based on the total mass of the hydrogel system. Low-ester pectin in Ca 2+ The first layer of gel network is formed under the action of xanthan gum in Fe 3+ A second gel network is formed under the action of [the process]. (2) Preparation of enzymatically hydrolyzed ethyl cellulose: Ethyl cellulose is dispersed in sodium acetate buffer, cellulase is added for enzymatic hydrolysis, then the enzyme is inactivated, and then centrifuged, washed and dried to obtain enzymatically hydrolyzed ethyl cellulose; The preferred amount of cellulase added is 0.1-6.0% of the mass of ethyl cellulose, the enzymatic hydrolysis temperature is 45-65 °C, the enzymatic hydrolysis time is 0.5-5 h, and the enzymatic hydrolysis pH is 4.5-6.0. The enzyme inactivation conditions are 80-100 ℃ for 5-20 min; (3) Preparation of network interpenetrating self-assembled reinforced oleogel: The enzymatic hydrolyzed ethyl cellulose obtained in step (2) is mixed with monoglyceride and DHA algal oil, heated to 130 °C under light-protected conditions and stirred to dissolve (30 min), and then cooled to form network interpenetrating self-assembled reinforced oleogel. The preferred mass ratio of DHA algal oil, enzymatically hydrolyzed ethyl cellulose, and monoglycerides is 88-92:4-6:4-6; Enzymatically hydrolyzed ethyl cellulose and monoglycerides form an interpenetrating self-assembled network structure in DHA algal oil; (4) Preparation of bigel antifreeze: The hydrogel obtained in step (1) is mixed with the oleogel obtained in step (3), and after high-speed shear emulsification and cooling, a bigel antifreeze is obtained; The preferred mass ratio of hydrogel to oleogel is 1:9 to 9:1; The optimal operating parameters for high-speed shear emulsification are: 6000~18000 rpm, 1~10 min; The preferred cooling temperature is 4 °C and the time is 12 h.

[0010] This invention's dual-gel antifreeze agent can be used to enhance the freeze-thaw quality of surimi products, such as fish sausages, fish balls, and fish cakes. Specific application methods are as follows: A dual-gel antifreeze agent is added to fish paste, which is then chopped, shaped, and heated to gel, resulting in fish paste products with improved freeze-thaw quality. The preferred amount of dual-gel antifreeze agent added is 1 to 10% of the fish paste mass.

[0011] The beneficial effects of this invention are as follows: The dual-gel antifreeze agent constructed in this invention provides dual protection through both hydrogel and olegel phases. This mitigates the dual damage to the surimi gel network caused by water migration and coarse ice crystal growth during freeze-thaw cycles, thereby reducing freeze-thaw losses and improving the quality of surimi products. The dual-gel antifreeze agent of this invention utilizes widely available raw materials and has a simple preparation process, making it suitable for quality protection of various frozen surimi products. Attached Figure Description

[0012] Figure 1 The process flow diagram for the preparation of the dual-gel antifreeze agent of this invention and its application in surimi products is shown below.

[0013] Figure 2 Graphs showing the freeze-thaw hardness results of the double gels in Examples 1-6 and Comparative Examples 1-6 after no freeze-thaw, one freeze-thaw cycle, and five freeze-thaw cycles.

[0014] Figure 3 The results of freeze-thaw centrifugation stability determination of the double gels in Examples 1-6 and Comparative Examples 1-6 after no freeze-thaw, 1 freeze-thaw cycle, and 5 freeze-thaw cycles are shown in the figure.

[0015] Figure 4 Comparison of freeze-thaw juice loss rates of surimi products from blank control group, Examples 1-4, and Comparative Examples 4, 6, and 7 after 1 and 5 freeze-thaw cycles.

[0016] Figure 5 Comparison of gel strength of surimi products from blank control group, Examples 1-4, and Comparative Examples 4, 6, and 7 after no freeze-thaw cycles, 1 freeze-thaw cycle, and 5 freeze-thaw cycles.

[0017] Figure 6 : Thiol content graphs of surimi products from blank control group, Examples 1-4, and Comparative Examples 4, 6, and 7 after no freeze-thaw cycles, 1 freeze-thaw cycle, and 5 freeze-thaw cycles.

[0018] Figure 7 Carbonyl content graphs of surimi products from blank control group, Examples 1-4, and Comparative Examples 4, 6, and 7 after no freeze-thaw cycles, 1 freeze-thaw cycle, and 5 freeze-thaw cycles.

[0019] Figure 8 Ice crystal morphology diagrams of surimi products from blank control group, Example 1, and Comparative Examples 4 and 6 after 1 and 5 freeze-thaw cycles. Detailed Implementation

[0020] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0021] In the following embodiments, Low-ester pectin (Hengyue Food Biotechnology Co., Ltd., food grade); xanthan gum (Shandong Gukang Biotechnology Co., Ltd., food grade); ethyl cellulose (Fufeng Group, food grade); cellulase (Xiasheng Industrial Group, 3500 u / g food grade); monoglycerides (Shanghai Xintai Industrial Co., Ltd., food grade); DHA algal oil (Xi'an Minglang Biotechnology Co., Ltd., 50% DHA food grade); calcium lactate (Shanghai Xintai Industrial Co., Ltd., food grade); ferric citrate (Shanxi Leda Biotechnology Co., Ltd., food grade); golden threadfin bream surimi (Qingdao Shengteng Seafood Co., Ltd., food grade).

[0022] Example 1

[0023] A bigel antifreeze agent, the preparation method of which includes the following steps: (1) Preparation of the double-network hydrogel: Low-ester pectin and xanthan gum were added to deionized water to make the mass fraction of low-ester pectin 1.5% and the mass fraction of xanthan gum 1.0%. The mixture was heated and stirred in a water bath at 70 ℃ for 20 min to ensure complete dissolution. 1 mol / L calcium lactate (Ca) was added at 40 ℃. 2+ The solution crosslinked low-ester pectin for 1 h to form the first network layer, and then 0.5 mol / L ferric citrate (Fe) was added. 3+ A solution was used to crosslink xanthan gum for 1 h to form a second network, resulting in a double-network hydrogel. The amount of calcium lactate solution added was 0.3% of the hydrogel system mass, and the amount of ferric citrate solution added was 0.2% of the hydrogel system mass. After stirring and cooling, a low-ester pectin / xanthan gum / Ca solution was obtained. 2+ / Fe 3+ Dual-network hydrogel.

[0024] (2) Preparation of enzymatically hydrolyzed ethyl cellulose: Ethyl cellulose was dispersed in sodium acetate buffer at pH 5.0, and cellulase was added. The amount of cellulase added was 1.0% of the mass of ethyl cellulose. Enzymatic hydrolysis was carried out at 55 °C for 2 h. After enzymatic hydrolysis, the enzyme was inactivated by treatment at 90 °C for 10 min. After separation, washing and drying, enzymatically hydrolyzed ethyl cellulose was obtained.

[0025] (3) Preparation of network interpenetrating self-assembled reinforced oleogel: DHA algal oil, enzymatic hydrolyzed ethyl cellulose and monoglyceride obtained in step (2) are mixed in a mass ratio of 90:6:4, heated to 130 °C in a constant temperature oil bath under light-protected conditions, and stirred for 30 min to fully dissolve it. Then, it is cooled to obtain enzymatic hydrolyzed ethyl cellulose / monoglyceride / DHA algal oil network interpenetrating self-assembled reinforced oleogel.

[0026] (4) Preparation of dual gel: The hydrogel obtained in step (1) and the oleogel obtained in step (3) are mixed at a mass ratio of 5:5, and emulsified by high-speed shearing at 12000 rpm for 4 min. Then, the mixture is cooled and crosslinked at 4 ℃ for 12 h to obtain a dual gel system.

[0027] In the dual-gel system obtained in Example 1, the low-ester pectin / xanthan gum / Ca 2+ / Fe 3+ The dual-network hydrogel is used to bind free water and restrict water migration. The enzymatically hydrolyzed ethyl cellulose / monoglycerate / DHA algal oil network interpenetrating self-assembly reinforced oleogel is used to improve the stability of the oil phase and form a hydrophobic barrier. After high-speed shear emulsification, the two phases form a dense network structure, thereby improving the freeze-thaw stability of the dual gel.

[0028] Example 2

[0029] The difference between Example 2 and Example 1 is that the low-ester pectin / xanthan gum / Ca in Example 1 is changed. 2+ / Fe 3+ The dual-network hydrogel was replaced with one without added Ca. 2+ and Fe 3+ The low-ester pectin / xanthan gum hydrogel with crosslinking agent; the composition of the remaining oleogels and the preparation methods of the dual gels are the same as in Example 1.

[0030] (1) Preparation of low-ester pectin / xanthan gum composite hydrogel: Low-ester pectin and xanthan gum were added to deionized water to make the mass fraction of low-ester pectin 1.5% and the mass fraction of xanthan gum 1.0%. The mixture was heated and stirred for 20 min in a water bath at 70 °C to dissolve it completely. No calcium lactate solution or ferric citrate solution was added. The mixture was then cooled to obtain low-ester pectin / xanthan gum composite hydrogel without the addition of ionic crosslinking agent.

[0031] (2) Preparation of enzymatically hydrolyzed ethyl cellulose: Ethyl cellulose was dispersed in sodium acetate buffer at pH 5.0, and cellulase was added at a concentration of 1.0% of the mass of ethyl cellulose. Enzymatic hydrolysis was carried out at 55 °C for 2 h. After the enzymatic hydrolysis was completed, the enzyme was inactivated by treatment at 90 °C for 10 min. After separation, washing and drying, enzymatically hydrolyzed ethyl cellulose was obtained.

[0032] (3) Preparation of network interpenetrating self-assembled reinforced oleogel: DHA algal oil, enzymatic hydrolyzed ethyl cellulose and monoglyceride obtained in step (2) are mixed in a mass ratio of 90:6:4, heated to 130 °C in a constant temperature oil bath under light-protected conditions, and stirred for 30 min to fully dissolve it. Then, it is cooled to obtain enzymatic hydrolyzed ethyl cellulose / monoglyceride / DHA algal oil network interpenetrating self-assembled reinforced oleogel.

[0033] (4) Preparation of dual gel: The hydrogel obtained in step (1) and the oleogel obtained in step (3) are mixed at a mass ratio of 5:5, and emulsified by high-speed shearing at 12000 rpm for 4 min. Then, the mixture is cooled and stabilized at 4 ℃ for 12 h to obtain the dual gel system.

[0034] Example 2 is used to illustrate the process without adding Ca. 2+ and Fe 3+ Under the condition of the crosslinking agent, the low-ester pectin / xanthan gum composite hydrogel forms a weak gel structure, and the density of the resulting bigel network is weaker than that of the bigel system in Example 1.

[0035] Example 3

[0036] The difference between Example 3 and Example 1 is that the enzymatically hydrolyzed ethyl cellulose in Example 1 is replaced with unenzymatically hydrolyzed ethyl cellulose, and the oleogel is prepared using unenzymatically hydrolyzed ethyl cellulose, monoglyceride, and DHA algal oil; the composition of the remaining hydrogel and the preparation method of the dual gel are the same as in Example 1.

[0037] (1) Preparation of the double-network hydrogel: Low-ester pectin and xanthan gum were added to deionized water to make the mass fraction of low-ester pectin 1.5% and the mass fraction of xanthan gum 1.0%. The mixture was heated and stirred in a water bath at 70 ℃ for 20 min to ensure complete dissolution. 1 mol / L calcium lactate (Ca) was added at 40 ℃. 2+ The solution crosslinked low-ester pectin for 1 h to form the first network layer, and then 0.5 mol / L ferric citrate (Fe) was added. 3+ A solution was used to crosslink xanthan gum for 1 h to form a second network, resulting in a double-network hydrogel. The amount of calcium lactate solution added was 0.3% of the hydrogel system mass, and the amount of ferric citrate solution added was 0.2% of the hydrogel system mass. After stirring and cooling, a low-ester pectin / xanthan gum / Ca solution was obtained. 2+ / Fe 3+ Dual-network hydrogel.

[0038] (2) Preparation of unhydrolyzed ethyl cellulose oleogel: DHA algal oil, unhydrolyzed ethyl cellulose and monoglyceride are mixed in a mass ratio of 90:6:4, heated to 130 °C in a constant temperature oil bath under light protection, and stirred for 30 min to fully dissolve it. Then, it is cooled to obtain unhydrolyzed ethyl cellulose / monoglyceride / DHA algal oil oleogel.

[0039] (3) Preparation of dual gel: The hydrogel obtained in step (1) and the oleogel obtained in step (2) are mixed at a mass ratio of 5:5, and emulsified by high-speed shearing at 12000 rpm for 4 min. Then, the mixture is cooled and stabilized at 4 ℃ for 12 h to obtain the dual gel system.

[0040] Example 3 illustrates that, without enzymatic hydrolysis of ethyl cellulose, the network structure enhancement effect of unhydrolyzed ethyl cellulose and monoglycerides in DHA algal oil is relatively limited, and the stability of the bigel oil phase network formed by them is weaker than that of the bigel system formed in Example 1.

[0041] Example 4

[0042] The difference between Example 4 and Example 1 is that the low-ester pectin / xanthan gum / Ca in Example 1 is replaced with... 2+ / Fe 3+ The dual-network hydrogel was replaced with one without added Ca. 2+ and Fe 3+ The low-ester pectin / xanthan gum hydrogel with crosslinking agent was prepared by replacing the enzymatically hydrolyzed ethyl cellulose in Example 1 with unenzymatically hydrolyzed ethyl cellulose; the preparation methods of the other dual gels were the same as in Example 1.

[0043] (1) Preparation of low-ester pectin / xanthan gum composite hydrogel: Low-ester pectin and xanthan gum were added to deionized water to make the mass fraction of low-ester pectin 1.5% and the mass fraction of xanthan gum 1.0%. The mixture was heated and stirred for 20 min in a water bath at 70 °C to dissolve it completely. No calcium lactate solution or ferric citrate solution was added. The mixture was then cooled to obtain low-ester pectin / xanthan gum composite hydrogel without the addition of ionic crosslinking agent.

[0044] (2) Preparation of unhydrolyzed ethyl cellulose oleogel: DHA algal oil, unhydrolyzed ethyl cellulose and monoglyceride are mixed in a mass ratio of 90:6:4, heated to 130 °C in a constant temperature oil bath under light protection, and stirred for 30 min to fully dissolve it. Then, it is cooled to obtain unhydrolyzed ethyl cellulose / monoglyceride / DHA algal oil oleogel.

[0045] (3) Preparation of dual gel: The hydrogel obtained in step (1) and the oleogel obtained in step (2) are mixed at a mass ratio of 5:5, and emulsified by high-speed shearing at 12000 rpm for 4 min. Then, the mixture is cooled and stabilized at 4 ℃ for 12 h to obtain the dual gel system.

[0046] Example 4 illustrates that, in the absence of Ca2+ in the hydrogel... 2+ / Fe 3+ Under conditions of ionic crosslinking and without the use of enzymatically hydrolyzed ethyl cellulose to reinforce the oleogel, the network density and structural stability of the dual-gel system are both weaker than those of the dual-gel system obtained in Example 1.

[0047] Example 5

[0048] The difference between Example 5 and Example 1 is that the low-ester pectin / xanthan gum / Ca in Example 1 is replaced with... 2+ / Fe 3+The dual-network hydrogel was replaced with one using only Ca. 2+ Cross-linked low-ester pectin / xanthan gum, without added Fe 3+ The cross-linking system; the composition of the remaining oleogel and the preparation method of the dual gel are the same as in Example 1.

[0049] (1) Preparation of Ca only 2+ Cross-linked hydrogel: Low-ester pectin and xanthan gum were added separately to deionized water to achieve a pectin mass fraction of 1.5% and a xanthan gum mass fraction of 1.0%. The mixture was heated and stirred in a 70 °C water bath for 20 min to ensure complete dissolution. Then, 1 mol / L calcium lactate (Ca) was added at 40 °C. 2+ The solution was used to crosslink low-ester pectin for 1 h, wherein the amount of calcium lactate solution added was 0.3% of the mass of the hydrogel system. After stirring evenly and cooling, low-ester pectin / xanthan gum / Ca was obtained. 2+ Hydrogel.

[0050] (2) Preparation of enzymatically hydrolyzed ethyl cellulose: Ethyl cellulose was dispersed in sodium acetate buffer at pH 5.0, and cellulase was added at a concentration of 1.0% of the mass of ethyl cellulose. Enzymatic hydrolysis was carried out at 55 °C for 2 h. After the enzymatic hydrolysis was completed, the enzyme was inactivated by treatment at 90 °C for 10 min. After separation, washing and drying, enzymatically hydrolyzed ethyl cellulose was obtained.

[0051] (3) Preparation of network interpenetrating self-assembled reinforced oleogel: DHA algal oil, enzymatic hydrolyzed ethyl cellulose and monoglyceride obtained in step (2) are mixed in a mass ratio of 90:6:4, heated to 130 °C in a constant temperature oil bath under light-protected conditions, and stirred for 30 min to fully dissolve it. Then, it is cooled to obtain enzymatic hydrolyzed ethyl cellulose / monoglyceride / DHA algal oil network interpenetrating self-assembled reinforced oleogel.

[0052] (4) Preparation of dual gel: The hydrogel obtained in step (1) and the oleogel obtained in step (3) are mixed at a mass ratio of 5:5, and emulsified by high-speed shearing at 12000 rpm for 4 min. Then, the mixture is cooled and stabilized at 4 ℃ for 12 h to obtain the dual gel system.

[0053] This Example 5 is for illustrative purposes only, and only uses Ca. 2+ During cross-linking, low-ester pectin can form a certain gel network, but xanthan gum lacks Fe. 3+ The mediated ionic crosslinking results in a bigel network with weaker density than the bigel system in Example 1.

[0054] Example 6

[0055] The difference between Example 6 and Example 1 is that the low-ester pectin / xanthan gum / Ca in Example 1 is changed. 2+ / Fe 3+The dual-network hydrogel was replaced with Fe-only hydrogel. 3+ Cross-linked low-ester pectin / xanthan gum hydrogel, without added Ca 2+ The cross-linking system; the composition of the remaining oleogel and the preparation method of the dual gel are the same as in Example 1.

[0056] (1) Preparation of Fe-only 3+ Cross-linked hydrogel: Low-ester pectin and xanthan gum were added separately to deionized water to achieve a pectin mass fraction of 1.5% and a xanthan gum mass fraction of 1.0%. The mixture was heated and stirred in a 70 °C water bath for 20 min to ensure complete dissolution. Then, 0.5 mol / L ferric citrate (Fe3+) was added at 40 °C. 3+ Crosslinking of xanthan gum with a solution of ferric citrate for 1 h, wherein the amount of ferric citrate solution added is 0.2% of the mass of the hydrogel system, and after stirring evenly and cooling, low-ester pectin / xanthan gum / Fe2+ solution is obtained. 3+ Hydrogel.

[0057] (2) Preparation of enzymatically hydrolyzed ethyl cellulose: Ethyl cellulose was dispersed in sodium acetate buffer at pH 5.0, and cellulase was added at a concentration of 1.0% of the mass of ethyl cellulose. Enzymatic hydrolysis was carried out at 55 °C for 2 h. After the enzymatic hydrolysis was completed, the enzyme was inactivated by treatment at 90 °C for 10 min. After separation, washing and drying, enzymatically hydrolyzed ethyl cellulose was obtained.

[0058] (3) Preparation of network interpenetrating self-assembled reinforced oleogel: DHA algal oil, enzymatic hydrolyzed ethyl cellulose and monoglyceride obtained in step (2) are mixed in a mass ratio of 90:6:4, heated to 130 °C in a constant temperature oil bath under light-protected conditions, and stirred for 30 min to fully dissolve it. Then, it is cooled to obtain enzymatic hydrolyzed ethyl cellulose / monoglyceride / DHA algal oil network interpenetrating self-assembled reinforced oleogel.

[0059] (4) Preparation of dual gel: The hydrogel obtained in step (1) and the oleogel obtained in step (3) are mixed at a mass ratio of 5:5, and emulsified by high-speed shearing at 12000 rpm for 4 min. Then, the mixture is cooled and stabilized at 4 ℃ for 12 h to obtain the dual gel system.

[0060] Example 6 is for illustrative purposes only, and only Fe is used. 3+ During cross-linking, xanthan gum can form a certain ionic cross-linking network, but low-ester pectin lacks Ca2+. 2+ The induced gel enhancement effect results in a bigel network with weaker support than the bigel system of Example 1.

[0061] Comparative Example 1

[0062] Comparative Example 1 is a low-ester pectin hydrogel that does not mix with oleogel to form a bigel.

[0063] Preparation of low-ester pectin hydrogel: Low-ester pectin was added to deionized water to make the mass fraction of low-ester pectin 1.5%, and heated and stirred in a water bath at 70 ℃ for 20 min to fully dissolve it. After cooling, low-ester pectin hydrogel was obtained.

[0064] Comparative Example 2

[0065] Comparative Example 2 is a xanthan gum hydrogel that does not mix with oleogel to form a bigel.

[0066] Preparation of xanthan gum hydrogel: Xanthan gum was added to deionized water to make the xanthan gum mass fraction 1.0%, and heated and stirred in a water bath at 70 ℃ for 20 min to fully dissolve it. Then it was cooled to obtain xanthan gum hydrogel.

[0067] Comparative Example 3

[0068] Comparative Example 3 is a low-ester pectin / xanthan gum compound hydrogel that does not mix with oleogel to form a bigel.

[0069] Preparation of low-ester pectin / xanthan gum composite hydrogel: Low-ester pectin and xanthan gum were added to deionized water to make the mass fraction of low-ester pectin 1.5% and the mass fraction of xanthan gum 1.0%. The mixture was heated and stirred in a water bath at 70 ℃ for 20 min to fully dissolve it. After cooling, the low-ester pectin / xanthan gum composite hydrogel was obtained.

[0070] Comparative Example 4

[0071] Comparative Example 4 is a dual-network hydrogel that does not mix with oleogel to form a bigel.

[0072] Preparation of the dual-network hydrogel: Low-ester pectin and xanthan gum were added separately to deionized water to achieve a pectin mass fraction of 1.5% and a xanthan gum mass fraction of 1.0%. The mixture was heated and stirred in a 70 ℃ water bath for 20 min to ensure complete dissolution. Then, 1 mol / L calcium lactate (Ca) was added at 40 ℃. 2+ The solution crosslinked low-ester pectin for 1 h to form the first network layer, and then 0.5 mol / L ferric citrate (Fe) was added. 3+ A solution was used to crosslink xanthan gum for 1 h to form a second network, resulting in a double-network hydrogel. The amount of calcium lactate solution added was 0.3% of the hydrogel system mass, and the amount of ferric citrate solution added was 0.2% of the hydrogel system mass. After stirring and cooling, a low-ester pectin / xanthan gum / Ca solution was obtained. 2+ / Fe 3+ Dual-network hydrogel.

[0073] Comparative Example 5

[0074] Comparative Example 5 is an ethyl cellulose / monoglyceride / DHA algal oil oleogel that does not mix with hydrogel to form a bigel.

[0075] Preparation of ethyl cellulose / monoglyceride / DHA algal oil oleogel: DHA algal oil, ethyl cellulose and monoglyceride were mixed in a mass ratio of 90:6:4, heated to 130 °C in a constant temperature oil bath under light-protected conditions, and stirred for 30 min to ensure complete dissolution. The mixture was then cooled to obtain ethyl cellulose / monoglyceride / DHA algal oil oleogel.

[0076] Comparative Example 6

[0077] Comparative Example 6 is a network interpenetrating self-assembly enhanced oleogel that does not mix with hydrogel to form a bigel.

[0078] (1) Preparation of enzymatically hydrolyzed ethyl cellulose: Ethyl cellulose was dispersed in sodium acetate buffer at pH 5.0, and cellulase was added. The amount of cellulase added was 1.0% of the mass of ethyl cellulose. Enzymatic hydrolysis was carried out at 55 °C for 2 h. After the enzymatic hydrolysis was completed, the enzyme was inactivated by treatment at 90 °C for 10 min. After separation, washing and drying, enzymatically hydrolyzed ethyl cellulose was obtained.

[0079] (2) Preparation of network interpenetrating self-assembled reinforced oleogel: DHA algal oil, enzymatic hydrolyzed ethyl cellulose and monoglyceride obtained in step (1) are mixed in a mass ratio of 90:6:4. The mixture is heated to 130 °C in a constant temperature oil bath under light-protected conditions and stirred for 30 min to fully dissolve it. Then it is cooled to obtain enzymatic hydrolyzed ethyl cellulose / monoglyceride / DHA algal oil network interpenetrating self-assembled reinforced oleogel.

[0080] Comparative Example 7

[0081] Comparative Example 7 uses a commercial antifreeze composed of sucrose and sorbitol, without the addition of hydrogels, oleogels, or bigels formed by the two.

[0082] Sucrose and sorbitol were mixed evenly at a mass ratio of 1:1 to obtain a commercial antifreeze agent. The obtained commercial antifreeze agent was added to fish paste at a mass of 8.0% of the fish paste mass, of which sucrose and sorbitol were added at a mass of 4.0% each.

[0083] To further evaluate the freeze-thaw protection effect of the dual-gel system compared to single hydrogels and single oleogels, the dual-gels obtained in Examples 1-4 and the Ca obtained in Comparative Example 4 were selected. 2+ / Fe 3+ The double cross-linked hydrogel, the enzymatically hydrolyzed ethyl cellulose-reinforced oleogel obtained in Comparative Example 6, and the sucrose / sorbitol commercial antifreeze agent obtained in Comparative Example 7 were applied to surimi products, and a blank control group without the addition of gel materials was set up.

[0084] Example 1 was used to evaluate the freeze-thaw protection effect of the complete bigel system; Example 2 was used to investigate the lack of Ca in the hydrogel. 2+ / Fe 3+ The effects of ionic crosslinking were investigated. Example 3 examined the effect of using unenzymatically hydrolyzed ethyl cellulose in the oleogel. Example 4 examined the effect of using hydrogels without ionic crosslinking and oleogels without enzymatically hydrolyzed ethyl cellulose. Comparative Examples 4 and 6 were used to evaluate the improvement effects of hydrogels and oleogels alone on the freeze-thaw quality of surimi products, respectively. Comparative Example 7 evaluated the freeze-thaw protection effect of a traditional sucrose / sorbitol commercial antifreeze agent. By comparing the blank control group, the commercial antifreeze agent group, the hydrogel-only group, the oleogel-only group, and the dual-gel group, the water-binding effect of the hydrogel and the structural support and hydrophobic barrier effect of the oleogel were analyzed to verify the synergistic freeze-thaw protection effect of the dual-gel combination. The differences between the dual-gel antifreeze agent of this invention and traditional sugar-based antifreeze agents in maintaining the freeze-thaw quality of surimi products were also compared.

[0085] (1) Preparation of surimi products: Frozen surimi was thawed at 4 ℃, chopped for 1 min, and then salt was added at a rate of 2.0% of the surimi mass. The double gels obtained in Examples 1-4 and the single gels in Comparative Examples 4 and 6 were then added at a rate of 5% of the surimi mass. The mixture was chopped for another 2 min, then stuffed into intestines and kept warm at 40 ℃ for 30 min. After heating at 90 ℃ for 20 min, the surimi products were obtained after cooling. The blank control group did not add the double gels, and the total amount of commercial antifreeze added was 8% of the surimi mass. The rest of the preparation method was the same.

[0086] (2) Freeze-thaw treatment: The surimi product obtained in step (1) is frozen at -18 ℃ for 24 h and then thawed at 4 ℃ for 12 h as one freeze-thaw cycle. After repeating the freeze-thaw cycle 5 times, it is used for freeze-thaw quality evaluation.

[0087] Freeze-thaw hardness determination of dual-gel and single-gel systems

[0088] Samples from Examples 1-6 (unfrozen), Examples 1-6 (frozen and thawed once), and Examples 1-6 (frozen and thawed five times) were placed in a 50 mL cylindrical glass beaker with a sample height of 2.0 cm for hardness measurement. The probe was approached to the sample at a pre-test speed of 8 mm / s and a test speed of 10.0 mm / s, with a trigger force of 10.0 g. The probe penetrated the sample by 5 mm and then returned to the starting position at a post-test speed of 10.0 mm / s.

[0089] Result: As Figure 2As shown, after five freeze-thaw cycles, the hardness of each group decreased. The hardness of Examples 1-6 decreased to 238.1, 157.2, 172.2, 103.3, 140.0, and 128.6 g, respectively, indicating that freeze-thaw cycles damage the structural strength of the samples. In contrast, Example 1 maintained a high hardness of 238.1 g after five freeze-thaw cycles, indicating that its double-crosslinked hydrogel and network-interpenetrating self-assembled reinforced olegel helped maintain the biphase network structure and mitigate freeze-thaw damage. The hardness of Comparative Examples 1-6 was lower than that of the Examples, indicating that the freeze-thaw stability of a single hydrogel or olegel system is lower than that of a dual-gel system. The hardness of Comparative Example 4 was 100.1 g, higher than that of Comparative Example 3 (86.5 g) which did not undergo ionic crosslinking, indicating that Ca... 2+ / Fe 3+ Crosslinking enhances the low-ester pectin / xanthan gum hydrogel network, restricts water migration, and reduces damage to the gel system from ice crystals. The hardness of Comparative Example 6 was 94.7 g, higher than that of the un-enzymatically hydrolyzed Comparative Example 5 (79.6 g), indicating that enzymatically hydrolyzed ethyl cellulose helps improve the continuity and stability of the oleogel network. Therefore, both ionic crosslinking and enzymatic hydrolysis of ethyl cellulose can improve the freeze-thaw protection of the gel system. Furthermore, compared to Comparative Examples 4 and 6, the dual-gel combination significantly enhances the hardness of the hydrogel and oleogel alone, achieving a synergistic effect greater than the sum of its parts (1+1>2).

[0090] Determination of freeze-thaw centrifugal stability of dual-gel and single-gel systems

[0091] Samples from Examples 1-6 (unfrozen), 1-frozen, and 5-frozen samples, and Comparative Examples 1-6, were collected. Equal masses of the dual gel (3 g) were placed in centrifuge tubes, and the total mass was weighed. The tubes were then centrifuged at 10000 r / min for 20 min at 25 °C. The centrifuge tubes were inverted on filter paper for 5 min to completely absorb the centrifuged oil and water, and the masses of the dual gel and centrifuge tubes were weighed. The calculation formula is as follows:

[0092] Where M0 is the total mass before centrifugation, M t This represents the total mass after centrifugation.

[0093] Result: As Figure 3 As shown, Example 1 exhibited the highest centrifugal stability, reaching 100.00% before freeze-thaw cycles and maintaining 96.6% after five freeze-thaw cycles, significantly higher than the other treatment groups. This indicates that Ca... 2+ / Fe 3+The synergistic effect of the double-crosslinked hydrogel and the reinforced olegel helps to form a more stable and dense biphase network structure, which can resist ice crystal damage. The centrifugal stability of Comparative Examples 1-6 after 5 freeze-thaw cycles decreased to 25.7%, 29.2%, 25.1%, 51.7%, 22.0%, and 49.3%, respectively, all lower than that of the Examples. After 5 freeze-thaw cycles, the centrifugal stability of Comparative Example 4 was 51.7%, higher than that of Comparative Example 3 (25.1%) without ionic crosslinking, indicating that Ca... 2 + / Fe 3+ Crosslinking enhances the low-ester pectin / xanthan gum hydrogel network and reduces water loss after freeze-thaw cycles. The centrifugal stability of Comparative Example 6 was 49.3%, higher than that of Comparative Example 5 (22.0%) without enzymatic hydrolysis, indicating that enzymatically hydrolyzed ethyl cellulose helps improve the continuity and structural stability of the oleogel network. Therefore, both ionic crosslinking and enzymatic hydrolysis of ethyl cellulose can improve the freeze-thaw stability of the gel system. Furthermore, compared to Comparative Examples 4 and 6, Example 1 showed significantly enhanced centrifugal stability after five freeze-thaw cycles, demonstrating a synergistic effect.

[0094] Determination of freeze-thaw juice loss rate

[0095] Take the surimi products obtained from the blank control group, Examples 1-4, Comparative Examples 4, 6, and 7, and record the sample mass before freeze-thaw treatment as M0. After 1 and 5 freeze-thaw cycles, gently absorb the sample surface and the precipitated free water with filter paper, and record the sample mass after freeze-thaw treatment as M1. The calculation formula is as follows:

[0096] Where M0 represents the mass of the sample before freezing; M1 represents the mass of the sample after thawing and drying the surface moisture.

[0097] Result: As Figure 4 As shown, the freeze-thaw loss rate of the surimi products in each group increased with the number of freeze-thaw cycles. After 5 freeze-thaw cycles, the freeze-thaw loss rates of Examples 1-4 were 6.4%, 13.7%, 12.7%, and 15.8%, respectively, which were lower than the 24.6% of the blank group, indicating that different gel systems all have a certain freeze-thaw protection effect. The freeze-thaw loss rate of Example 1 was the lowest, significantly lower than the blank control group and the examples and comparative groups. This shows that the dual-gel antifreeze agent of the present invention, through Ca... 2+ / Fe 3+The combined effect of the dual-crosslinked hydrogel and the network-interpenetrating self-assembled reinforced olegel can synergistically reduce juice leakage during freeze-thaw cycles. Comparative Example 7, using a commercial sucrose / sorbitol antifreeze agent, showed a thawing loss rate of 11.7% after 5 freeze-thaw cycles, lower than Examples 2-4 but still higher than Example 1, indicating that the freeze-thaw protection effect of the complete dual-gel system of this invention is superior to traditional sugar-based antifreeze agents. In contrast, Example 4 showed a loss rate of 15.8% after 5 freeze-thaw cycles, indicating a relatively weak protective effect, further demonstrating that the lack of complete hydrogel ionic crosslinking and olegel network reinforcement reduces the freeze-thaw stability of the system. While the thawing loss rates of Comparative Examples 4 and 6 were lower than the blank control group, they were significantly higher than those of the examples, indicating that the lack of key components or the failure to form a complete dual-gel synergistic network reduces both the water-binding capacity and freeze-thaw stability of the system.

[0098] Determination of gel strength parameters

[0099] Surimi products from Examples 1-4, Comparative Examples 4, 6, and 7 (unfrozen, after 1 and 5 freeze-thaw cycles, blank control group, and comparative examples 1-4) were cut into uniform cylindrical samples, and their gel strength was determined using a texture analyzer. The gel strength was measured using a TA-XT Plus C texture analyzer equipped with a spherical probe (P / 5s). The surimi products were first cut into cylinders 15 mm × 20 mm high. The test was then conducted at a constant speed of 1 mm / s. The trigger force was 5 g, and the gel strength was determined by multiplying the breaking force by the breaking distance (g). The gel strength is calculated using cm.

[0100] Result: As Figure 5 As shown, the gel strength of the surimi products in each group decreased to varying degrees with increasing freeze-thaw cycles. After 5 freeze-thaw cycles, the gel strengths of Examples 1-4 were 378.3, 225.8, 249.9, and 218.4 g, respectively. cm, significantly higher than the blank control group's 140.5 g. cm. Example 1 maintained 378.3 g after 5 freeze-thaw cycles. The gel strength (cm) was significantly higher than that of the blank control group and each comparative group, indicating that the dual-gel antifreeze agent of this invention has significant application value in improving the gel structure stability of freeze-thawed surimi. Comparative Example 7 used a conventional commercial antifreeze agent composed of sucrose / sorbitol, and the gel strength after 5 freeze-thaw cycles was 257.0 g. The gel strength of the present invention is lower than that of Example 1, indicating that the freeze-thaw protection effect of the dual-gel antifreeze is superior to that of traditional sugar-based antifreeze. The gel strengths of Comparative Examples 4 and 6 are 189.9 and 168.4 g, respectively. The concentration of 1 cm was higher than that of the blank control group, but lower than that of each example, especially Example 1. This indicates that a single gel structure or the absence of key network reinforcing components can still alleviate freeze-thaw damage to some extent, but its structural protection effect is weaker than that of a complete dual-gel system. Therefore, the dual gel obtained in this invention can provide synergistic freeze-thaw protection.

[0101] thiol group determination

[0102] Surimi products from unfrozen, unthawed, and 1-5 freeze-thaw cycles-tested blank control groups, Examples 1-4, Comparative Examples 4, 6, and 7 were used. The content of sulfhydryl and carbonyl groups was used as indicators of protein oxidation degree. 0.3 g of surimi product was weighed and added to 20 mL of buffer (0.2 M tris-HCl, 8 M urea, 10 mM EDTA, 2% SDS, pH 6.8), and then homogenized at 8000 rpm for 1 min. Subsequently, it was shaken overnight. The next day, 3.6 mL of the supernatant was collected, and 0.4 mL of 0.1% DTNB was added. The mixture was then reacted at 40 °C for 25 min, and the absorbance was measured at 412 nm. The calculation formula is as follows:

[0103] In the formula, A is the absorbance value of the sample at 412 nm; D is the dilution factor, 11; ε is the molar absorptivity, 13600 L / mol. cm; C is the protein concentration, 5 mg / mL.

[0104] Result: As Figure 6 As shown, with the increase of freeze-thaw cycles, the total sulfhydryl content of the surimi products in each group showed a decreasing trend, indicating that repeated freeze-thaw cycles promoted the oxidation of protein sulfhydryl groups and aggravated the deterioration of surimi protein structure. The total sulfhydryl content of the blank control group further decreased to 16.1 nmol / mg after 5 freeze-thaw cycles. The total sulfhydryl contents of Examples 1-4 were 62.3, 35.0, 38.1, and 33.2 nmol / mg, respectively, all significantly higher than those of the blank control group. Among them, the total sulfhydryl content of Example 1 was the highest, significantly higher than that of the blank control group, indicating that the dual-gel antifreeze agent of the present invention can effectively slow down the oxidative loss of protein sulfhydryl groups during freeze-thaw cycles. After 5 freeze-thaw cycles, the total sulfhydryl content of the commercial antifreeze agent group in Comparative Example 7 was 40.8 nmol / mg, which was higher than that of Examples 2-4, but still significantly lower than that of Example 1, indicating that the complete dual-gel system of the present invention has a better protective effect on protein sulfhydryl groups than the traditional sucrose / sorbitol antifreeze agent. The total thiol content of Comparative Examples 4 and 6 was 28.1 and 23.2 nmol / mg, respectively. Although this was higher than that of the blank control group, it was lower than that of each example, indicating that the inhibitory effect on protein oxidation was relatively weak when key components were missing or a complete bigel synergistic network was not formed.

[0105] Carbonyl determination

[0106] Weigh 1 g of surimi product and add it to 20 mL of phosphate buffer (20 mM Na2HPO4, 0.6 M NaCl, pH 6.0). Homogenize at 8000 rpm for 3 min. Adjust the concentration of the sample dispersion to 2 mg / mL. Then, take 1 mL of the sample and add 1 mL of 10 mM DNPH (dissolved in 2 M HCl). Incubate in the dark for 1 h, shaking every 15 min. Add 1 mL of 15% trichloroacetic acid (TCA), shake to mix, centrifuge at 5000 rpm for 10 min, remove the supernatant, wash thoroughly with an ethanol-ethyl acetate mixture (1:1, v / v), and dissolve the precipitate with 3 mL of 6 M guanidine hydrochloride. Measure the absorbance at 370 nm. The calculation formula is as follows:

[0107] In the formula, A is the absorbance value of the sample at 370 nm; D is the dilution factor, 3; ε is the molar absorptivity, 22000 L / mol. cm; C is the protein concentration, 1 mg / mL.

[0108] Result: As Figure 7 As shown, the carbonyl content of the surimi products in each group increased with the number of freeze-thaw cycles, indicating that repeated freeze-thaw cycles promoted the oxidation of surimi proteins and the formation of carbonylation products. After 5 freeze-thaw cycles, the carbonyl content of the blank control group increased to 47.0 nmol / mg, while that of Examples 1-4 were 20.6, 36.9, 34.8, and 38.4 nmol / mg, respectively, all lower than that of the blank control group. Among them, Example 1 had the lowest carbonyl content, indicating that the dual-gel antifreeze agent of the present invention can effectively inhibit the formation of carbonyl groups in surimi proteins during repeated freeze-thaw cycles, and reduce protein oxidation and structural deterioration. The carbonyl content of the commercial antifreeze agent group in Comparative Example 7 was 29.2 nmol / mg, which was lower than that of Examples 2-4, but still higher than that of Example 1, indicating that the dual-gel antifreeze agent of the present invention has a better inhibitory effect on protein oxidation than the traditional sucrose / sorbitol antifreeze agent. After five freeze-thaw cycles, the carbonyl content of Comparative Example 4 and Comparative Example 6 was 41.8 and 43.4 nmol / mg, respectively. Although these were lower than the blank control group, they were significantly higher than that of Example 1, indicating that the inhibitory effect of hydrogel or oleogel alone on protein oxidation was relatively limited, while the synergistic effect of Example 1 was obvious.

[0109] Observation of ice crystal morphology and structure

[0110] Surimi products from the blank control group, Example 1, Comparative Example 4, and Comparative Example 6, after 1 and 5 freeze-thaw cycles, were collected. The frozen surimi products were cut into 4 mm × 4 mm × 4 mm cubes and then fixed in 4% paraformaldehyde solution for 22 h. The samples were then eluted with a gradient of ethanol (30%, 50%, 70%, 80%, and 95%, v / v) and embedded in paraffin. The samples were cut into 4 μm thick slices using a cryostat, placed on glass slides, and then dewaxed with xylene. After HE staining, the samples were observed using an E100 optical microscope.

[0111] Result: As Figure 8 As shown, the blank control group exhibited larger ice crystal voids after freeze-thaw treatment, indicating that repeated freeze-thaw cycles led to ice crystal growth and coarsening, damaging the surimi gel network. Compared to the blank control group, the ice crystals in Comparative Examples 4 and 6 were smaller and fewer in number, but the improvement effect was weaker than that in Example 1. In Example 1, the ice crystals were smaller and more uniformly distributed, indicating that the network interpenetrating self-assembled reinforced oleogel portion of the dual-gel antifreeze agent of this invention forms a hydrophobic barrier, which can more effectively limit ice crystal growth and coarsening, thereby mitigating freeze-thaw damage.

Claims

1. A bigel antifreeze agent, characterized in that, It is obtained by mixing a dual-network hierarchical hydrogel and a network interpenetrating self-assembled reinforced oleogel, followed by high-speed shear emulsification and cooling. The aforementioned dual-network hierarchical hydrogel is made by dissolving low-ester pectin and xanthan gum in water, and then using Ca... 2+ Fe 3+ Formed by sequential cross-linking; The network interpenetrating self-assembly enhanced oleogel is formed by using DHA algal oil as the oil phase and compounding it with enzymatically hydrolyzed ethyl cellulose and monoglycerides.

2. The method for preparing the bigel antifreeze agent as described in claim 1, characterized in that, The method includes: (1) Preparation of double network hierarchical hydrogel: Dissolve low-ester pectin and xanthan gum in water, first add calcium lactate solution, crosslink the low-ester pectin at 30~60 ℃ for 1 h to form the first network; then add ferric citrate solution, crosslink the xanthan gum at 30~60 ℃ for 1 h to form the second network, and obtain double network hierarchical hydrogel. (2) Preparation of enzymatically hydrolyzed ethyl cellulose: Ethyl cellulose is dispersed in sodium acetate buffer, cellulase is added for enzymatic hydrolysis, then the enzyme is inactivated, and then centrifuged, washed and dried to obtain enzymatically hydrolyzed ethyl cellulose; (3) Preparation of network interpenetrating self-assembled reinforced oleogel: The enzymatic hydrolyzed ethyl cellulose obtained in step (2) is mixed with monoglyceride and DHA algal oil, heated to 130 °C under light-protected conditions and stirred to dissolve, and then cooled to form network interpenetrating self-assembled reinforced oleogel. (4) Preparation of bigel antifreeze: The hydrogel obtained in step (1) is mixed with the oil gel obtained in step (3), and after high-speed shear emulsification and cooling, a bigel antifreeze is obtained.

3. The preparation method according to claim 2, characterized in that, In step (1), low-ester pectin and xanthan gum are added to water and stirred at 70 °C for 20 min to dissolve them completely. The mass fraction of low-ester pectin in the resulting mixed aqueous solution is 0.5-2.0%, and the mass fraction of xanthan gum is 0.5-2.5%.

4. The preparation method according to claim 2, characterized in that, In step (1), the concentration of calcium lactate solution is 1.0 mol / L and the concentration of ferric citrate solution is 0.5 mol / L; based on the total mass of the hydrogel system, the amount of calcium lactate solution added is 0.1~1% and the amount of ferric citrate solution added is 0.1~1%.

5. The preparation method according to claim 2, characterized in that, In step (2), the amount of cellulase added is 0.1~6.0% of the mass of ethyl cellulose, the enzymatic hydrolysis temperature is 45~65 ℃, the enzymatic hydrolysis time is 0.5~5 h, and the enzymatic hydrolysis pH is 4.5~6.0; the enzyme inactivation conditions are 80~100 ℃ for 5~20 min.

6. The preparation method according to claim 2, characterized in that, In step (3), the mass ratio of DHA algal oil, enzymatically hydrolyzed ethyl cellulose, and monoglyceride is 88~92:4~6:4~6.

7. The preparation method according to claim 2, characterized in that, In step (4), the mass ratio of hydrogel to oleogel is 1:9 to 9:

1.

8. The preparation method according to claim 2, characterized in that, In step (4), the working parameters for high-speed shear emulsification are: 6000~18000 rpm, 1~10 min; cooling temperature 4 ℃, time 12 h.

9. The dual-gel antifreeze agent as described in claim 1 is used to enhance the freeze-thaw quality of surimi products.

10. The application as described in claim 9, characterized in that, The method is as follows: A dual-gel antifreeze agent is added to fish paste, which is then chopped, shaped, and heated to gel, resulting in fish paste products with improved freeze-thaw quality. The amount of dual-gel antifreeze agent added is 1-10% of the fish paste mass.

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