Study On The Enzymatic Preparation Of Rice Antioxidant Peptides

Rice is one of the main grains of human beings. According to statistics, over 100 nations treat rice as staple food, and rice owns 25% of all grains. Asia is the primary region of the production and consumes of rice, has 91% of total yield on the earth. Rice total annual yield is up to 1.85 hundred ton which is 37% of total production of the world in China. For centuries, the production and deep processing of rice are highly concerned by bromatology scientists.Rice protein is a high-quality vegetable protein. Recently, many kinds of products are exploited according to rice protein features, such as food additive, high-nutrition protein powder and peptides with special creature features.Materials of the study are rice protein form Changsha Hunan. Rice protein were hydrolyzed by Aspergillus subtilis acid protease, Aspergillus subtilis neutral protease, Bacillus subitilis alkali protease, trypsin and complex enzyme, respectively, with the indexes of yield and reducing power of peptides in hydrolyzate. The result showed that optimum enzyme was Bacillus subitilis alkali protease when rice protein makes anti-oxidation intestinal peptides.In the experiment, Bacillus subitilis alkali protease was used as rice hydrolyzing enzyme. Temperature, time and pH of hydrolysis and enzyme dosage of rice protein hydrolysis were optimized by quaternionically quadratic common rotating combination. It was found that optimum complex of rice protein hydrolysis was enzyme dosage 60U/mL with pH9.5 and at thetemperature of 50℃for 180min, and the yield of peptides was 27.7% under the conditions.The thesis firstly discussesd scavenging hydroxy radical and superoxide radical activities of rice peptides in the rice protein hudrolyzate. It was indicated that the activities of rice peptides were weaker than vitamin C, but still showed a certain activity. Rice peptides have exploiting future as natural antioxidants.The thesis firstly discussed the isolation of rice anti-oxidant peptides. The componentsⅠ,Ⅱ,Ⅲof rice protein hydrolyzates isolated by sephadex G-15 have all a certain reducing ability. That means all of them can resist to oxidation, andⅠ>Ⅲ>Ⅱ.The peptides from rice protein hydrolyzed by alkali protease can clear epactal hydroxy radical and have a certain reducing ability, illustrating that they have marked resistance to oxidation. It becomes a primary exploiting way of rice deep processing that how to use the character mentioned above.