Study On The Preparation Of Wheat Germ Peptides And Their Flavor Activity

Wheat is an important food crop in my country,and its by-product,wheat germ,has obvious resource advantages and nutritional value.However,at present,the processed products of wheat germ are mostly primary processed products with low added value,so they cannot meet the needs of consumers,resulting in a huge waste of resources.At the same time,with the change of consumption concept,people’s demand for nutritious and healthy food is getting higher and higher,among which low-sodium and natural flavor peptides have been widely recognized.However,the current research on flavor peptides still focuses on the preparation process and few studies on their activity.Therefore,this paper uses wheat germ to prepare flavor active peptides to study the effects of enzymatic hydrolysis and fermentation on the flavor characteristics and physiological activity of products,in order to prepare flavor peptides with good flavor and specific physiological activities.Provide technical and theoretical guidance for improving the processing utilization rate of wheat germ and the added value of products.The main research contents and results are as follows:The defatted wheat germ powder was used as the raw material,and the peptide yield and sensory score were used as the measurement indicators.The volatile substances,non-volatile substances and peptide molecular weights in the products were determined by GC/MS and high performance liquid chromatography,and the antioxidant activity of the products with molecular weights less than 3 000 Da was studied.The experimental results show that the optimal enzymatic hydrolysis conditions are:enzymatic hydrolysis p H was 7,substrate concentration 2%,enzymatic hydrolysis temperature 50℃,enzyme addition 4%;optimal fermentation conditions:yeast addition 5 g/100 m L,fermentation time was 48 h,fermentation p H was 4,and the ratio of material to liquid was 1:14.Under these conditions,the yields of peptides were 8.17%±0.70%and 16.76%±2.48%,respectively,and the obtained products showed a certain salty and fresh flavor as a whole.The contents of volatile substances and taste substances in the enzymatic hydrolysate and fermentation products were different,but the molecular weight distribution of peptides in the products were all concentrated in the range of molecular weight less than 3 000 Da.The antioxidant activity of the product with molecular weight less than 3 000 Da was studied,and it was found that the enzymatic hydrolysis product had better ABTS free radical scavenging ability(IC₅₀=0.448mg/m L)and hydroxyl radical scavenging ability(IC₅₀=0.574 mg/m L),The fermented product had good ABTS free radical scavenging ability(IC₅₀=0.156 mg/m L).The products with molecular weight less than 3 000 Da were further separated,purified and identified by ultrafiltration,gel filtration chromatography and reversed-phase high performance liquid chromatography,and the amino acid sequence of wheat germ peptide was determined by liquid chromatography-mass spectrometry.By means of simulation,six polypeptides with umami taste were screened,which were EY,DF,EEL,DWK,TDEE,and VDSE in turn.Using molecular docking again,it was predicted that they may have hypoglycemic and hypotensive activities.Solid-phase synthesis was performed on the screened wheat germ peptides（EY,DF,EEL,DWK,TDEE,VDSE）.The electronic tongue was used for further sensory analysis,and sodium glutamate was used as a control to study its taste characteristics.The results showed that the synthetic peptides showed obvious sour taste and a certain umami aftertaste.