CN-121970897-A - Method for preparing gel-delivered epigallocatechin gallate by utilizing soybean protein isolate composite dialdehyde starch to overcome isoelectric point

Abstract

The invention discloses a method for preparing gel delivery epigallocatechin gallate by utilizing soybean protein isolate composite dialdehyde starch to overcome isoelectric points, and the prepared gel can carry EGCG with high efficiency, and belongs to the field of food processing. The method comprises the steps of dispersing SPI and DAS with the concentration of 1% in ultrapure water respectively, stirring, adjusting pH and hydrating to obtain a soybean protein isolate solution and a dialdehyde starch solution. SPI and DAS were mixed in a ratio of 4:1, 2:1, 1:1, 1:2, and 1:4, stirred under alkaline conditions (pH=8.0) for 2h, then adjusted to weakly acidic conditions (pH=6.0), and EGCG was added in an amount of 1/30 of the protein mass, and stirred again for 1: 1 h. And regulating the pH value of the obtained mixture to 4.0 and 4.5 respectively, standing for 24 h, and centrifuging to obtain the composite gel carrying EGCG. The SPI-DAS gel prepared by the method is free from adding any additive, the obtained composite gel is more environment-friendly and safer, has higher stability, and can improve the bioavailability of EGCG by carrying EGCG. The invention has simple process and environment protection, solves the application difficulty of SPI at isoelectric point to a certain extent, and widens the application of the isolated soy protein in food industry.

Inventors

• JIANG LIANZHOU
• ZHU WEIXIANG
• YANG BOWEN
• XU TIANHE
• XIE JUNFENG
• WANG HUAN

Assignees

• 东北农业大学

Dates

Publication Date

20260505

Application Date

20260128

Claims (5)

1. 1. A method for preparing gel delivery epigallocatechin gallate by utilizing soy isolate protein composite dialdehyde starch to overcome isoelectric point comprises the following steps: Dispersing SPI and DAS with concentration of 1% in ultrapure water respectively, stirring at speed of 700 r/min for 2h to dissolve completely, standing at 4deg.C for 12h to hydrate protein completely, preparing compound solution with mass ratio of SPI to DAS of 4:1, 2:1, 1:1, 1:2, 1:4, adjusting pH value to 8.0 with 0.1M NaOH, and stirring at normal temperature for 2h to ensure complete reaction; Step two, taking stirred SPI, namely DAS=4:1, 2:1, 1:1, 1:2 and 1:4 samples, regulating the pH value to 6.0, adding EGCG powder with the mass of 1/30 of that of the SPI into each sample, isolating air, stirring for 1h, regulating the pH value to 4.0 and 4.5 respectively, standing for 24 h, centrifuging for 20 min under the centrifugal force of 6,000Xg, and removing supernatant to obtain a gel sample.
2. 2. The optimal preparation parameters of the SPI-DAS composite gel loaded with EGCG are SPI: DAS=1:2, and pH is 4.5.
3. 3. According to the invention, the food-grade SPI and DAS are used as raw materials to prepare the composite gel, so that the addition of other modification modifiers can be avoided, and the stability and safety of the composite gel are effectively improved.
4. 4. The invention has simple production process, low cost, environmental protection and contribution to industrial production.
5. 5. The method utilizes SPI-DAS to prepare the composite gel, and the prepared composite gel has good performance and can carry EGCG with high efficiency, thereby effectively improving the bioavailability and stability of EGCG.

Description

Method for preparing gel-delivered epigallocatechin gallate by utilizing soybean protein isolate composite dialdehyde starch to overcome isoelectric point Technical Field The invention belongs to the technical field of food processing, and relates to a method for preparing gel delivery epigallocatechin gallate by utilizing soybean protein isolate composite dialdehyde starch to overcome isoelectric points. Background Soy Protein Isolate (SPI) is an important food ingredient and is also a well-accepted complete vegetable protein whose composition includes acidic amino acids and their amides, basic amino acids, polar and nonpolar amino acids, and cysteines, which make it structurally with many highly reactive groups and thus has quite excellent properties in terms of molecular interactions. The gel property is used as an important functional characteristic for intuitively reflecting the interaction of SPI molecules, so that the application prospect of SPI is further widened, the application range is expanded, and the unmodified SPI gel is often poor in mechanical strength and stability in the food processing and storage processes. Oxidation of polysaccharides is a more effective means of enhancing protein-polysaccharide interactions to improve the texture and properties of protein-polysaccharide complex gels. Compared with the covalent bond, rather than the hydrogen bond and the noncovalent effect of the Schiff base formed by oxidized polysaccharide, the covalent effect can keep the conformation of the protein to the greatest extent, thereby ensuring that the original excellent functional characteristics are not affected and making up the defect of single protein gel. Starch is a natural polysaccharide from plants, consisting of amylose and amylopectin. Natural starch is often limited in practical application and production due to its poor water solubility, stability, etc., and four basic modifications have been developed to accommodate the production system, namely physical, chemical, enzymatic and genetic, all of which are directed to the three highly reactive hydroxyl groups (C2, C3 and C6) on the starch molecule. Among them, chemical modification is the most commonly used modification method by changing or introducing new functional groups without changing the natural properties of starch. The oxidation of starch is one of the most important means, and commonly used oxidants are mainly permanganate, nitrogen dioxide, sodium hypochlorite, periodate and chromate, wherein sodium periodate is used as a special selective oxidant, and can act on C2 and C3 in a targeted manner to obtain dialdehyde starch (DAS), and the dialdehyde starch is applied to the fields of food, paper making and medicine. Epigallocatechin-3-gallate (EGCG) is the most abundant bioactive compound in catechin, is a typical flavone-3-ol phenolic substance, and has great potential in resisting tumor, resisting virus and regulating and treating various chronic diseases. However, its high instability such as easy degradation under light and heat conditions, results in low bioavailability and severely limits clinical transformation and practical application. In addition, self-assembly, chelation, partial oxidation, etc. of EGCG under physiological conditions may reduce the bioactivity during gastrointestinal digestion. Researchers have therefore developed various methods to improve the bioavailability and stability of EGCG. According to the invention, the SPI and the DAS are used as raw materials to prepare gel at the SPI isoelectric point and carry the EGCG, so that the biological accessibility and stability of the EGCG are effectively improved, the development of a more stable small molecular nutrient carrier is facilitated, the application difficulty of the SPI is solved to a certain extent, and the method has important significance in expanding the development of the SPI in gel based on vegetable proteins. Disclosure of Invention The invention aims to prepare gel at SPI isoelectric point by using SPI and DAS as raw materials and carry EGCG, so that the composite gel has better property and carries the maximum amount of EGCG and improves the bioavailability and stability of EGCG. The technical problems to be solved by the invention are realized by the following technical scheme: A method for preparing gel delivery epigallocatechin gallate by utilizing soy isolate protein composite dialdehyde starch to overcome isoelectric point comprises the following steps: Dispersing SPI and DAS with concentration of 1% in ultrapure water respectively, stirring at speed of 700 r/min for 2h to dissolve completely, standing at 4deg.C for 12h to hydrate protein completely, preparing compound solution with mass ratio of SPI to DAS of 4:1, 2:1, 1:1, 1:2, 1:4, adjusting pH value to 8.0 with 0.1M NaOH, and stirring at normal temperature for 2h to ensure complete reaction; Step two, taking stirred SPI, namely DAS=4:1, 2:1, 1:1, 1:2 and 1:4 samples, regulating the pH