Evaluation Of The Digestibility And Thermal Stability Of Whey Protein Hydrolysates

Whey protein is nutrient-rich and has many functional propertities.There has been a lot of whey protein products in the market,in recent years,modification of whey protein is widely used.Enzymatic hydrolysis is a mild modification method.Enzymatic hydrolysis of whey protein can not only significantly improve its application characteristics but also produce biologically active peptides with specific physiological functions.This article focuses on the basic physicochemical properties of the hydrolyzed products of whey protein after enzymatic hydrolysis,nutritional properties,thermal stability and its application in infant formula liquid milk.Neutral protease was chosen as the hydrolysing enzyme of whey protein.The optimal conditions for hydrolyzing whey protein were:hydrolysis temperature 45?,pH 7 and E/S 2500 U/g.The degree of hydrolysis of the hydrolyzed products at different hydrolysis times was determined.The hydrolyzed whey proteins with hydrolysis times of 10,30,90,and 120 minutes were selected as the subject of this experiment.At the same time,WPC 8350,the commercial hydrolyzed whey protein product was chosen as a reference.Compare the similarities and differences between the commercial hydrolyzed whey protein product and the laboratory-made hydrolyzed whey protein.After whey protein was hydrolyzed,the protein content decreased slightly and ash content increased.Free amino acid content increased,the content of essential amino acid and non-essential amino acid was more abundant than before.With the increase of the degree of hydrolysis,the molecular weight distribution of hydrolysate gradually decreased.The proportion of low molecular weight gradually increased.Compared with unhydrolyzed whey protein,protein with large molecular weight decreased.Therefore,many short peptides and free amino acids appeared,the in vitro digestibility of hydrolysates was significantly higher than that of unhydrolyzed whey protein.And there was a positive correlation between digestibility and degree of hydrolysis.Using the free sulfhydryl content,particle size distribution,and Turbiscan stability as indicators,determination of thermal stability of hydrolysed whey protein and whey protein at different heat treatment temperatures,different heat treatment times,different pH and different Ca2+concentrations,respectively,were done.Compared with the whey protein before and after hydrolysis,the thermal stability after hydrolysis was significantly improved.Whey protein and hydrolyzed whey protein were used as protein supplements in the infant formula liquid milk.The two proteins were added separately.After the analysis of the product,there was no obvious difference in product stability,but the digestion of the product with hydrolysed whey protein was significantly better than the former.