Fabrication Of Heat-treated Soy Protein Isolate-EGCG Conjugates And Its Study As Functional Carrier

This study mainly prepared functional complex carrier based on soybean protein isolated(SPI)/heat-treatment soy protein isolates(HSPI)-epigallocatechin-3-gallate(EGCG).Then,the heat treatment effect on the reaction of SPI with EGCG and its complex properties was explored.The interaction mechanism of different complex carrier(SPI-EGCG and HSPI-EGCG)and curcumin(C)to form load system,and the stability,sustained release ability and bioaccessibility of curcumin in different load system were evaluated.The main researches of this study are as follows:(1)The effect of heat treatment on the covalent reaction and covalently-linked complex properties of soybean protein isolate and EGCG was explored.The results show HSPI exposes more active binding sites(-NH₂and-SH)and possesses more superior structure,making it can easier combine with EGCG.Compared to SPI-EGCG,HSPI-EGCG has a higher EGCG binding rate,antioxidant improving capacity and smaller particle size.(2)Two functional complex carriers,SPI-EGCG and HSPI-EGCG,were prepared using alkali covalent crosslinking method.The interaction mechanism and binding capacity of the two complex carriers and curcumin were explored,and the particle size,morphology and antioxidant properties of the complex carrier-curcumin load system were evaluated.The results show that hydrophobic interaction,hydrogen bonding and electrostatic interaction drives the interaction between complex carrier and curcumin.Curcumin opens the spherical shape structure of complex carrier,making the load systems(SPI-EGCG-C and HSPI-EGCG-C)show sheet shape structure.Compared to SPI-EGCG,HSPI-EGCG had stronger combination capacity,higher curcumin load rate and stronger synergistic antioxidant capacity.The load system,HSPI-EGCG-C,shows smaller particle size and thinner sheet shape structure.(3)The protection ability,stability and bioaccessibility of curcumin in SPI-C,SPI-EGCG-C and HSPI-EGCG-C load systems were studied.The results shows that the bioaccessibility of curcumin in the complex carriers decreased,in addition,compared with single carrier SPI,the complex carriers show a sustained release behavior after 6 hours,and the performance of HSPI-EGCG-C was more significant In high temperature,acid and cold storage away from light environment,the complex carriers perform better protection capacity and stability than that of the single carrier,and the HSPI-EGCG-C load system has superior protection ability and stronger stability.The results of this paper not only benefit the development of functional food,cosmetics and drug delivery systems,but also solve the environmental instability of single protein carrier at a certain extent,and overcome the acid deposition problem of protein.