Study On Wheat Germ Hydrolysis By Enzyme And The Antioxidant Activity Of Hydrolysates

Wheat is the collective name for genus Triticum, widely cultivated in all overthe world. The yield of wheat stands second in the world, which is higher thanpaddy rice and lower than corn. Wheat germ is a by-product of wheat processingwith high nutritional value. The current use of wheat germ is mainly concentratedin the extraction of germ oil, but defatted wheat germ is underutilized. Wheatgerm contains the rich high quality protein, in this dissertation, a method ofpreparation of wheat germ protein hydrolysates have been researched, w hichwould provides the theoretical foundations for the utilization of wheat germprotein hydrolysates.This article use defatted wheat germ as raw material to prepare antioxidativepeptides. On the basis of the methods which combine the dissolution with a lkaliand hydrolysis with α-amylase and deposition with acid, wheat germ protein wasextracted by ultrasound-assisted method. The conditions of hydrolytic pretreatm-ent of wheat germ protein were investigated. This experiment also include: purifyof antioxidative peptides and detection of the purified antioxidative peptides. Theresults are as follows:Extraction of wheat germ protein. The conditions of ultrasound assistedmethod are as follows: ultrasonic power80W, ultrasonic temperature60℃,ultrasonic time30min, and in this conditions the yield radio and the purity of theprotein has reached77.99%and86.53%, respectively. The result showed that theultrasonic–assisted has a higher extraction and shorten the extraction time.The conditions of hydrolytic pretreatment of wheat germ protein. Theexperiment was conducted to study the process parameters on enzymatichydrolysis and antioxidant activity of hydrolysates by five protease. The resultsshowed that the neutral protease was the best single enzyme, the neutral protea seand the alkaline protease were the best double-enzyme. In addition, single enzymehad a better enzyme hydrolysis result by comparison with the double-enzyme. Theoptimum hydrolytic conditions were: substrate concentration4%, neutral proteasedosage6000u/g, temperature50℃, and pH value7.5. Under this conditions, theantioxidant activity of hydrolysates attained maximum when hydrolysis time270min, and the DH was36.70%, the content of peptide was15.14mg/mL, thescavenging activities on DPPH radical was55.13%, the redu cing power(700nm) is0.615.Refining of wheat germ protein hydrolysates. After the sample was dealed byultrafiltration, desalting with macroporous was investigated. The results showed that the sample which can through MWCO3000Da membrane has a betterantioxidative activity. After desalting, the salt content changed from11.64%to2.42%, the desalting rate arrived82.22%. After refining, the antioxidative activityof the wheat germ protein hydrolysates was improved.Antioxidant of wheat germ peptide. Stronger antioxidant activities of wheatgerm peptide were obsovered in6antioxidant systems in vitro. Although theantioxidant activity is not as well as the antioxidant usually used in food industry,but as functional ingredients added in natural health food, the wheat germ peptidehas a bright prospect of application in the future.