Study On The Extraction Of Wheat Germ Protein And Their Antioxidant Activity Of Enzymolysis Product

Wheat germ is the nutritional souce of wheat seed and contains 30% of protein which is the excellent potential souce of plant protein. The protein existed in wheat germ contains many amino acid sequences which may have biological activity. Thus, taking wheat germ protein as the material to develop functional peptides is the effective way to explore and use wheat germ.The objective of this study is to optimize the condition of wheat germ protein extraction by using supersonic wave auxiliary, study the preparation of wheat germ peptides and their antioxidant activity, and explore the separation conditions of hydrolysate of wheat germ protein.The results were as the following:1. The optimal conditons for protein extraction were as following: the ratio of wheat germ and water was 1:20, the power of supersonic machine was 200W, extraction time was 25 min and the pH of the extraction solution was 9.0.The protein extraction rate could reach to 83.45% under the optimal conditions and it increased 14.43% compared to the rate of 69.02% obtained from the extraction metnod which wheat germ protein dissolved with alkali solution and precipited with acid. The protein purity extracted under the optimal conditions was 87.50%.2. The optimal hydrolysis enzyme for wheat germ protein was Alcalase2.4L. There was no liner relationship between the ability of scavenging·OH and hydrolysis degree. The optimal hydrolysis conditions determined by the single factor and response surface optimization experiment were that pH was 7.8, temperature was 61℃, enzyme concentration was 6.8%, and the hydrolysis time was 3h.The·OH scavenging percentage of hydrolysate under the optimal conditions could reached to 72.9%(10mg/mL).3. Stronger antioxidant activities of hydrolysate of wheat germ protein were obsovered in 6 antioxidant systems in vitro.The scavenging ablity of O₂^-,·OH and DPPH·and reducing activity were in dose-dependent manner and the IC50 was 6.2mg/mL,3.5 mg/mLå’Œ2.3mg/mL,respectively. Moreover, the hydrolysate of wheat germ protein could inhibite the oxidation of linoleic acid and soybean oil.4. The optimal conditions for the separation of hydrolysate of wheat germ protein by the column of SephadexG-15 were that the sample concentration was 20 mg/mL, 0.05 mol/L of ammonium bicarbonate was as the elute and the flow rate of the elute was 0.5 mL/min. The hydrolysate could be separated into three components under the optimal separation conditions and the component of second peak had stronger antioxidant activity, and its IC50 was 1.68mg/mL, and its moleclar weight range was about 1000Da.