A crosslinking agent for improving the thermal stability of amino substrates and its application

Abstract

This invention relates to a crosslinking agent for improving the thermal stability of amino substrates and its application. The crosslinking agent for improving the thermal stability of amino substrates is one or more of glucuronic acid, galacturonic acid, glucuronide, methyl glucuronide, and methyl galacturonide. It improves substrate performance by reacting with the amino substrate through Maillard reactions or amidation reactions via its contained active aldehyde, carboxyl, or ester groups. This crosslinking agent exhibits significant crosslinking effect, good biocompatibility, and high permeability.

Description

Technical Field

[0001] This invention relates to the field of food crosslinking agents, and more particularly to a crosslinking agent for improving the thermal stability of amino substrates and its application. Background Technology

[0002] Crosslinking agents, as a class of functional additives, play a crucial role in bridging linear macromolecular chains (such as proteins and polysaccharides) into three-dimensional network structures through chemical bonding or physical interactions. This molecular network construction can significantly enhance the mechanical strength, swelling properties, and thermal stability of hydrogels, thereby meeting the diverse needs of various industries and thus possessing significant application value in food processing, biomedicine, and the development of novel materials.

[0003] Current research focuses on developing novel cross-linking systems that combine high efficiency, permeability, and good biocompatibility to enhance the stability of hydrogels and thus meet their application performance requirements. Based on differences in their mechanisms of action, existing cross-linking systems are mainly divided into two categories: chemical and biological. While chemical cross-linking agents (such as glutaraldehyde and citric acid) possess highly efficient cross-linking properties, their potential cytotoxicity and negative impact on matrix flavor characteristics limit their application in the food industry. Biological cross-linking agents are showing a diversified development trend: enzyme-based cross-linking agents (represented by transglutaminase) have been successfully applied to meat product reconstitution and edible film preparation, but their large molecular properties and insufficient permeability limit their wide application scope; natural small-molecule cross-linking agents such as genipin, while possessing excellent biocompatibility, can cause secondary effects such as matrix browning and the formation of bitter substances. Therefore, novel cross-linking agents with high efficiency, safety, and good permeability still need to be developed.

[0004] Patent application number CN202410595039.6 discloses a food-grade crosslinking agent and its application. This crosslinking agent is not only safe but also has good permeability and can crosslink large substrates. However, its crosslinking effect is limited. This application aims to develop a crosslinking agent with high permeability and more significant crosslinking effect. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a crosslinking agent for improving the thermal stability of amino substrates and its application. The crosslinking agent has the characteristics of significant crosslinking effect, good biocompatibility and high permeability.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: A crosslinking agent for improving the thermal stability of amino substrates, wherein the crosslinking agent is one or more of glucuronic acid, galacturonic acid, glucuronide lactone, methyl glucuronide, and methyl galacturonide, and improves substrate performance by reacting with the amino substrate through Maillard reaction and amidation reaction by the active groups aldehyde, carboxyl, or ester, respectively.

[0007] Furthermore, this application also provides a method for applying the crosslinking agent, wherein the weight ratio of the crosslinking agent to the amino substrate ranges from 1:1 to 1:5000.

[0008] Furthermore, the amino substrate is a hydrogel or a hydrogel precursor; the application method is as follows: immerse the target hydrogel or hydrogel precursor in an aqueous solution of a crosslinking agent, or mix the target hydrogel or hydrogel precursor with a crosslinking agent, with a crosslinking temperature of 50-150℃ and a crosslinking time of 0.5-6h.

[0009] Furthermore, the amino substrate is one of the following: rehydrated sea cucumber, fresh shrimp, fresh fish, fresh beef, fresh mutton, and fresh pork.

[0010] Furthermore, the crosslinking agent aqueous solution used has a mass fraction of 0.25-4% and a pH of 6-7.

[0011] The present invention employs the above-described structure and has the following advantages: 1. From the perspective of the crosslinking agent itself: First, uronic acid and its esters can effectively cross-link with amino macromolecules to form a stable hydrogel structure. Second, the cross-linking agent has a small molecular weight, allowing it to penetrate more easily into macromolecules or bulk materials; this high permeability ensures more uniform cross-linking. Third, the cross-linking products of this agent are biodegradable and possess good biocompatibility.

[0012] 2. From the perspective of crosslinking agent application: The crosslinking agent in this application can crosslink with amino substrates to form a stable gel structure, for example: Firstly, the rehydrated sea cucumbers treated with the cross-linking agent described in this application exhibit significantly improved thermal and storage stability. Specifically, after high-temperature sterilization, they do not exhibit instability issues such as tissue disintegration, surface collapse, or blurred shape and outline. When used as a raw material for deep processing or as a final product, their storage stability is significantly better than that of ordinary rehydrated sea cucumbers, with a firm texture, good chewiness, and moderate hardness.

[0013] Secondly, the cross-linking agent of this application can form a stable gel network structure with proteins in common aquatic products such as shrimp and squid, effectively reducing moisture loss during high-temperature cooking and enhancing meat firmness and elasticity. Furthermore, the cross-linking agent of this application can inhibit protein degradation and oxidation, extend shelf life, reduce the risk of spoilage, and improve product quality.

[0014] Thirdly, the cross-linking agent of this application can also cross-link with common meat products, giving them a stable structure. During high-temperature and high-pressure processes, protein denaturation and moisture loss are reduced, allowing the meat to better maintain its shape, texture, and nutritional components. When used as a raw material for further processing or as a final product such as ready-to-eat canned goods, the product quality will not decline due to high-temperature and high-pressure sterilization, increasing its economic value. Furthermore, the use of the cross-linking agent of this application also helps enhance the antioxidant and antibacterial properties of meat, delaying protein degradation and microbial growth during storage, thereby extending the product's shelf life. Attached Figure Description

[0015] Figure 1 Images showing the state of sea cucumbers treated with different cross-linking agents; Figure 2 Images of shrimp and squid after treatment with different cross-linking agents; Figure 3 Figures showing the state of chicken, pork, and beef after treatment with different cross-linking agents; Figure 4 The TVBN variation trend of chicken treated with different cross-linking agents during storage; Figure 5 The TVBN variation trend of pork treated with different cross-linking agents during storage; Figure 6 The TVBN variation trend of shrimp treated with different cross-linking agents during storage; Figure 7 This is a comparison image of ε-polylysine before and after crosslinking. Detailed Implementation

[0016] To clearly illustrate the technical features of this solution, the invention will be described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0017] (I) Crosslinking principle The specific crosslinking principle of the crosslinking agent of this invention is as follows: the aldehyde group in the crosslinking agent can undergo a Maillard reaction with the amino substrate; the carboxyl or ester group can undergo an amidation reaction with the amino substrate. This means that crosslinking can be formed when different functional groups of the same molecule undergo the above reactions with different amino molecules.

[0018] (II) Application Experiment To test the effect of the crosslinking agent of the present invention, glucuronic acid, galacturonic acid, methyl galacturonate and glucuronide were used as crosslinking agent samples in Examples 1-4, and enzymatically hydrolyzed phosphate distarch was used as control sample. The following application experiments were conducted.

[0019] 2.1 Application Experiment 1 Take the crosslinking agent samples from Examples 1-4 and the control group samples, add water to prepare crosslinking agent aqueous solutions with a mass concentration of 1%, and adjust the pH to 6-7 with sodium hydroxide solution for later use.

[0020] Dried sea cucumbers were soaked for 24 hours to form rehydrated sea cucumbers (dry weight ratio 1:10) and divided into six groups. One group served as a blank control, while the remaining five groups were placed in the prepared cross-linking agent aqueous solution and cross-linked at 100℃ for 0.5-1 hour. After cross-linking, the cross-linking agent was washed off with clean water and the surface moisture was wiped dry. The state of the sea cucumbers after cooking is shown in the figure. Figure 1 The sea cucumber was tested for various properties including hardness, elasticity, adhesiveness and chewiness. The test results are shown in Table 1.

[0021] Table 1. Results of the effects of cross-linking agents on various parameters of sea cucumbers.

[0022] pass Figure 1 As can be seen from the appearance, the sea cucumbers treated with the cross-linking agent of this invention have a complete structure after steaming, while the sea cucumbers in the control group are soft and mushy with blurred shapes. Table 1 shows that the sea cucumbers treated with the cross-linking agent of this invention are superior to the sea cucumbers in the control group in terms of hardness, elasticity, adhesiveness, and chewiness. This indicates that the cross-linking agent of this application has good cross-linking activity and high permeability, and can significantly improve the high thermal stability and storage resistance of rehydrated sea cucumbers.

[0023] Furthermore, at the same mass concentration, the crosslinking agents of Examples 1-4 of this invention showed better treatment effects on sea cucumbers than the enzymatically hydrolyzed phosphate distarch control group. In particular, the sea cucumbers treated with glucuronide crosslinking exhibited significantly improved properties, more closely resembling those of fresh sea cucumbers. This indicates that the crosslinking agents of this application have certain advantages in crosslinking large substrates.

[0024] 2.2 Application Experiment 2 Take the crosslinking agent samples from Examples 1-4 and the control group samples, add water to prepare crosslinking agent aqueous solutions with a mass concentration of 2%, and adjust the pH to 6-7 with sodium hydroxide solution for later use.

[0025] Fresh shrimp and squid were purchased from the market and placed in equal volumes of pure water (blank group), the crosslinking agent of Examples 1-4 of this invention, and the crosslinking agent of the control group, respectively. Crosslinking was carried out at 100°C for 0.5-2 hours. After crosslinking, the crosslinking agent was rinsed off with clean water and the surface moisture was dried. The quality results of the shrimp and squid after cooking are shown in the figure. Figure 2 The results of parameters such as hardness, elasticity, adhesiveness, and chewiness of shrimp and squid are shown in Table 2.

[0026] Table 2. Results of the effects of cross-linking agents on various parameters of shrimp, fish, and squid.

[0027] pass Figure 2 It can be seen that the shrimp and squid in the blank group became loose and lost their elasticity after being subjected to high heat, while the shrimp and squid in the cross-linking agent experimental group of this application exhibited advantages such as firm texture and intact appearance. Table 2 shows that the shrimp and squid treated with the cross-linking agent in Examples 1-4 of this invention were superior to the blank group in terms of hardness, elasticity, adhesion, and chewiness. This indicates that the cross-linking agent of this invention has good cross-linking ability and high permeability, and can significantly improve the high-heat stability of these common aquatic products. Furthermore, treatment with the cross-linking agent of this invention helps reduce damage and breakage of shrimp and squid during processing and storage, making them more intact in appearance, firmer and more elastic in texture, thus making them more appealing to consumers and possessing higher economic value.

[0028] Furthermore, at the same mass concentration, a comparison between Examples 1-4 and the control group shows that the crosslinking agent in Examples 1-4 is more effective than that of enzymatically hydrolyzed phosphate distarch, indicating that the crosslinking agent of this application has certain advantages in crosslinking large substrates.

[0029] 2.3 Application Experiment 3 Take the crosslinking agent samples from Examples 1-4 and the control group sample of enzymatically hydrolyzed phosphate distarch, add water to prepare crosslinking agent aqueous solutions with a mass concentration of 2%, and adjust the pH to 6-7 with sodium hydroxide solution for later use.

[0030] Fresh chicken, pork, and beef were purchased from the market and placed in equal volumes of pure water (blank group) and the crosslinking agents described in Examples 1-4 of this invention, respectively, and crosslinked at 100°C for 0.5-2 hours. After crosslinking, the crosslinking agent was washed off with clean water and the surface moisture was wiped dry. The quality results of the chicken, pork, and beef obtained after cooking are shown in the figure. Figure 3 The results of parameters such as elasticity, chewiness, water holding capacity, and cooking loss rate of chicken, pork, and beef are shown in Table 3.

[0031] Table 3. Results of the effects of crosslinking agents on various parameters of chicken, pork and beef.

[0032] pass Figure 3It can be seen that the chicken, pork, and beef treated with the crosslinking agent of this invention exhibit advantages such as firmer texture and more intact appearance compared to the control group. Table 3 shows that the chicken, pork, and beef treated with the crosslinking agent of this invention are superior to the control group in terms of elasticity, chewiness, water retention, and other parameters, and the cooking loss rate is lower than that of the control group. This indicates that the crosslinking agent of this application has good crosslinking ability, which can significantly improve the water retention and high thermal stability of common meats, and help to expand the development of the ready-to-eat meat market. Furthermore, the crosslinking agent treatment of this invention helps to reduce damage and breakage of chicken, pork, and beef during processing and storage, making their appearance more intact, their texture firmer, and their taste more chewy.

[0033] Furthermore, a comparison between Examples 1-4 and the control group shows that the crosslinking agent in Examples 1-4 is more effective than enzymatically hydrolyzed phosphate distarch, indicating that the crosslinking agent of this application has certain advantages in crosslinking large substrates.

[0034] 2.4 Application Experiment 4 Take the crosslinking agent samples from Examples 1-4, add water to prepare crosslinking agent aqueous solutions with a mass concentration of 1%, and adjust the pH to 6-7 with sodium hydroxide solution for later use.

[0035] Fresh chicken, pork, and shrimp were purchased from the market and placed in equal volumes of pure water (blank group) and the crosslinking agents of Examples 1-4 of this invention, respectively, for crosslinking at 100°C for 0.5-2 hours. After crosslinking, the crosslinking agent was washed off with clean water and the surface moisture was wiped off. After boiling and cooling, they were stored in a refrigerated environment at 4°C for 7 days. Samples were taken every two days during this period to determine their volatile basic nitrogen (TVBN) content. The TVBN change trends of chicken, pork, and shrimp during storage are shown in the figures. Figure 4 , Figure 5 and Figure 6 .

[0036] TVBN is a key indicator characterizing the degree of protein degradation; a decrease in its value directly indicates that the sample spoilage process has been effectively inhibited. Through... Figure 4-6 It can be seen that the TVBN values ​​of chicken, pork, and shrimp treated with the crosslinking agent of this invention were significantly lower than those of the control group during storage. This indicates that the crosslinking agent of this application can significantly improve the storage stability of common meat products after heat treatment, and has important application value for expanding the ready-to-eat meat product market.

[0037] 2.5 Application Experiment 5 Dissolve 0.5 parts by weight of ε-polylysine in 5 parts by weight of water, then add 0.03 mmol of the crosslinking agent from Example 1 of this invention, stir thoroughly, and then react in an autoclave at 121°C for 15 minutes. Figure 7As can be seen, ε-polylysine forms a gel and changes color after cross-linking, while the uncross-linked control group shows a flowing solution state, indicating that ε-polylysine has undergone cross-linking to form an active gel.

[0038] It should be noted that the crosslinking agent of this application can be used in fields such as organic chemical industry, oil and gas industry, light industry and handicraft industry, general chemical industry, materials, environmental science and resource utilization, construction, inorganic chemical industry, and biomedical engineering, specifically including but not limited to food protein stability, clothing finishing of cotton fabric properties, coating film formation, new materials, biological modification, petroleum processing, and molecular imprinting technology.

[0039] The specific embodiments described above should not be construed as limiting the scope of protection of this invention. Any alternative modifications or variations made to the embodiments of this invention by those skilled in the art will fall within the scope of protection of this invention. All aspects not detailed in this invention are well-known to those skilled in the art.

Claims

1. A crosslinking agent for improving the thermal stability of amino substrates, characterized in that, The crosslinking agent is one or more of glucuronic acid, galacturonic acid, glucuronide lactone, methyl glucuronide, and methyl galacturonide, which improves substrate performance by reacting with amino substrates through Maillard reaction and amidation reaction by the active groups aldehyde, carboxyl, or ester, respectively.

2. The application of the crosslinking agent of claim 1 for improving the thermal stability of amino substrates, characterized in that, When applying, the weight ratio of crosslinking agent to amino substrate is in the range of 1:1 to 1:5000.

3. The application of the crosslinking agent for improving the thermal stability of amino substrates according to claim 2, characterized in that, The amino substrate is a hydrogel or a hydrogel precursor; The application method is as follows: immerse the target hydrogel or hydrogel precursor in an aqueous solution of the crosslinking agent, or mix the target hydrogel or hydrogel precursor with the crosslinking agent, with a crosslinking temperature of 50-150℃ and a crosslinking time of 0.5-6h.

4. The application of the crosslinking agent for improving the thermal stability of amino substrates according to claim 3, characterized in that, The amino substrate is one of the following: rehydrated sea cucumber, fresh shrimp, fresh fish, fresh beef, fresh mutton, or fresh pork.

5. The application of the crosslinking agent for improving the thermal stability of amino substrates according to claim 3, characterized in that, The crosslinking agent used has a mass fraction of 0.25-4% and a pH of 6-7 in aqueous solution.

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