A Study On Preparation And Enrichment Of Antioxidant Peptide From Wheat Germ

Wheat germ is a by-product of wheat processing, and the current use is mainly concentrated in the extraction of wheat germ oil, but they are very rarely use the defatted wheat germ. This article use defatted wheat germ as raw material to prepare antioxidative peptides with Alcalase2.4L. This experiment include: auxiliary enzymatic hydrolysis, purify of antioxidative peptides and detection of the purified antioxidative peptides.First of all the physical methods is used to improve the antioxidative activity of the Enzyme Hydrolysis. Ultrasound-Assisted Enzymatic Hydrolysis is an important way. On the basis of single-factor test, Response surface analysis method was applied to study the effects of ultrasonic power, ultrasonic time and ultrasonic temperature on the enzymatic hydrolysis of defatted wheat germ. The result showed that the optimal parameters are as follows: ultrasonic power 214W, ultrasonic time 3min and ultrasonic temperature 25℃.The predictive best DPPH radical scavenging rate is 62.4%, the actual scavenging rate is 61.2%.Microwave processing for raw materials is to make use of microwave thermal effects and improve the reaction efficiency of protein. Effect of microwave processing is studied to get the optimal time and optimal power on the DPPH radical scavenging rate. The results showed that: Microwave processing time for 1min, power of 200W, the DPPH radical scavenging rate of the solution eventually reached 71.26%.After the hydrolysis, powdered activated carbon was used to the solution for decolorization. Effects of decoloration were studied on the decolorizing rate and the reserved rate of nitrogen. Meanwhile, this study investigated the antioxidative activities of the hydrolysis of the decolorizing wheat germ. The result showed that when powdered activated carbon concentration 2%,decolorization time 30min and decolorization temperature 50℃, the decolorizing rate was 83.9% and the reserved rate of nitrogen was 60.6%. Antioxidative activity exhibited 62.4%, 0.162 and 31.9% of scavenging activities on DPPH radical, the reducing power and chelating effect on ferrous ion respectively.After the samples was dealed by ultrafiltration, desalting and desugaring with macroporous adsorption resin was investigated. The results showed that the molecular weight of the purified antioxidative peptides for less than 1000 accounted for 90.46%; after desaling, the salt content changed from 6.17% to 2.42%; Desugaring which were the main elements of the experiment, were operated by Acid Precipitation and macroporous adsorption resin. The results showed that, the desugaring rate arrived 33.92% and the protein was 58.69% after Acid Precipitation. After dealing with macroporous adsorption resin, the desugaring rate arrived 35.45% and the protein was 55.73%. Combining the two ways, the desugaring rate arrived 41.93% and the protein was 65.23%. Meanwhile, the antioxidative activity of the purified peptides was improved: scavenging activities on DPPH radical changed from 36.37% to 59.01%, the reducing power changed from 0.234 to 0.974 and chelating effect on ferrous ion increased from 72.07% to 88.37%. Finally, the yield of the purified peptides was 3%.