Emulsifying Properties Of Whey Protein Isolate Fibrils And The Effect Of Quercetin On Its Emulsifying Properties

The use of vegetable oil to replace animal fat in the process of emulsifying meat products will have a negative effect on product quality.The use of vegetable oil preemulsion instead of animal fat can not only reduce the content of saturated fatty acids in meat,,more beneficial to the health of consumers,but also better retain product quality.However,this kind of emulsion has the problem of physical instability and oxidative protein fibrosis will improve the hydrophobic ability of protein,and fibrosis of the structure can form stable interface membrane structure,improve the stability of the emulsion plant polyphenols has strong oxidation resistance,it can be to hydrophobic interactions such as hydrogen bonding forces combined with protein,affect the functional properties of protein.Therefore,in this paper,whey protein isolate was used as the raw material to prepare fibrous aggregates of proteins,and the main force of fiber formation and fiber properties were studied.Quercetin,a representative polyphenol,was used as the research object to explore the influence of quercetin and fiber interaction on emulsion emulsification.The main conclusions are as follows:1.Preparation and characterization of whey protein fiberThe whey protein with different contents was treated with low acid and high heat to study the fiber formation with different protein contents,the main force of fiber formation was studied,and the viscosity surface tension of the fiber was measured.The results showed that at 4% and 5% of the protein content,the netlike fibrous structure was found by afm.After the formation of the fiber,the surface hydrophobicity increased and the content of sulfhydryl group decreased,indicating that the hydrophobic interaction and disulfide bond were the main forces for the formation of the fiber.The viscosity of the fiber solution increases and the surface tension decreases,which is conducive to the formation of stable emulsion2.Emulsifying properties of whey protein fibersCompared with unmodified whey protein,the viscosity of emulsion with emulsifyingactivity and emulsifying stability was used as the basis,The effects of different protein /fiber additions(0%,1.5%,2.5% and 3.5%)on emulsion properties were determined at pH2,pH 5 and pH 7..The results showed that the particle size of pH 5 emulsion in the fiber group was the largest,and the particle size of the fiber emulsion was larger than that of the protein emulsion.The viscosity of different pH emulsions was pH 7>pH 5>pH 2,and the higher the protein dosage,the higher the viscosity of the emulsion.The addition of fiber increased the stability of different pH emulsions,pH 5,fiber addition 3.5% and pH 7,when the fiber dosage is 2.5% and 3.5%,a stable emulsion can be formed,while the emulsion prepared under other pH and protein / fiber conditions is unstable..3.Effect of quercetin on the structure and emulsification of whey protein fiberThe interaction of quercetin with different amounts of quercetin and its effect on the stability of emulsion were studied.The results showed that quercetin could inhibit the degree of lipid oxidation,but the antioxidant capacity was related to the amount of quercetin.The interaction between quercetin and whey protein fibers generated hydrophobic interaction,but also made the fiber structure unfold,exposing the hydrophobic groups hidden inside.The crosslinking products of quercetin and fiber will increase the particle size of the emulsion,increase the content of the interfacial protein,increase the viscosity of the emulsion,thus increasing the stability of the emulsion;however,quercetin has little effect on the emulsifying activity of the emulsion.