Studies On Hydrolytic Processing Of Wheat Embryo Protein And Antioxidant Of Hydrolysate

Wheat germ is a by-product of wheat production, protein content of which as high as 30% or more.Meanwhile, wheat germ protein is a complete protein containing 8 amino acids necessary to human health. In addition, wheat germ is rich in vitamin B family, VE, unsaturated fatty acid, lysine, dietary fiber and some functional trace elements. Wheat germ protein polypeptide chain will be broken by enzymes, and release a variety of peptide compounds, so that their functional properties are improved, and obtein certain biological activities. Therefore, this paper will make further analysis on the hydrolysates.The author selected three different proteases to hydrolyze wheat germ protein, and reached optimum process conditions for three kinds of enzymatic hydrolysis of wheat germ protein respectively through single factor and orthogonal tests. The experimental results showed that, under 50℃, pH value 7, the amount of enzyme [E/S]7%, and substrate concentration of 5%, the papain hydrolysis degree was 18.23%; under 55℃, pH value 6.5, the amount of enzyme [E/S]5%, and substrate concentration of 4%, the flavorzyme proteinase hydrolysis degree was 16.37%; under 55℃, pH value 6.5, the amount of enzyme [E/S]5%, and substrate concentration of 4%, the alkaline protease hydrolysis degree was 20.08%. Using SDS-polyacrylamide gelelectrophoresis to determine three kinds of protease hydrolysate molecule quantity, the results showed that the molecular weight of the hydrolysate of alkaline protease being the smallest, mostly concentrated under 14.4 KDa.Finally, further analysis of wheat germ protein hydrolysates hydrolyzed by alkaline protease was proceeded, the thermal characteristics analysis results showed that the hydrolysate had good thermal stability under 200℃; using MALDI-TOF/TOF on the molecular weight determination, the results showed that the amount of molecular hydrolysates mostly concentrated under 2000 Da; structural analysis and functional properties analysis of wheat germ protein hydrolysates using infrared spectroscopy showed that the solubility of hydrolysate was higher than wheat germ protein before hydrolysis; hydrolysate had better hygroscopicity, and relatively worse oil absorption; foamability and foaming stability of hydrolysate was higher than that of wheat germ protein; emulsification and emulsion stability of wheat germ protein were lower than hydrolysate; the experimental results also indicated that the moisture absorption of hydrolysate was relatively poor.In addition, the in vitro antioxidant activity of wheat germ protein hydrolysate was estimated using four indexes. Results showed that wheat germ protein hydrolysate had higher reducibility; DPPH free radical scavenging rate was up to 85.5%; with hydroxyl radical scavenging rate of 81.2%; the scavenging rate of the superoxide anion was 67%. Results of the study indicated that wheat germ protein hydrolysate has strong antioxidation.