Protease Treatment For The Stabilization Of Rice Bran And The Preparation Of Rice Bran Peptide

Rice bran is a mixture of pericarp,germ and broken rice.It is rich in nutritional components of coarse rice.The fresh rice bran is easy to rancid,which can affect its application.The current reported stabilization methods include physical treatment,chemical treatment and enzymatic hydrolysis.In this paper,three proteases were tested to stabilize rice bran.Procedure and effectiveness of enzymatic stabilization were discussed.The extraction and enzymolysis of rice bran protein and the biological activity of rice bran protein peptides were also investigated.The conclusions are as follows:1.Three proteolytic enzymes including alkaline protease,papain and trypsin were selected to investigate their efficiency in the stability of rice bran.The results showed that alkaline protease was better.Increasing the solid-liquid ratio and alkaline protease dosage was better for the effect of rice bran stabilization.Compared with the heating and microwave treatment,the rice bran treated with alkaline protease not only had a higher content of ?-oryzanol and total phenol,but also had better stabilization.2.The process of the rice bran protein extraction through alkali extraction was studied.By the orthogonal test,the most optimal extraction conditions were as follows: the amount of enzyme was 4.0%,the ratio of material to liquid was 1:10,the extraction time was 2.0h,the pH value was 11.0 and the temperature was 50.0 ?.Under this condition the protein extraction rate was 29.70%3.The DPPH clearance rate had been measured after the enzymolysis of papain and typsin on rice bran protein.The optimum combinations of hydrolysis of rice bran protein with papain were as follows: the time was 86.56 min,the temperature was 54.20 ?,the pH value was 6.30,the amount of enzyme was 3.96%.Under the optimal combination condition,the DPPH clearance rate was 50.63%.The optimal combinations of trypsin to hydrolyze rice bran protein were as follows : the time was 68.00 min,the temperature was 35.00 ?,the amount of enzyme was 3.96%,the pH value was7.41.Under the optimal combination condition,the DPPH clearance rate was 42.85%.4.The enzymatic hydrolysis degree had been measured after the enzymolysis of papain,typsin and alkaline protease on rice bran protein.The results showed that the hydrolysate with enzymatic hydrolysis degree of 11.26%(papain),12.67%(trypsin)and 16.43%(alkaline protease)had the highest NK cell activity.5.The effect of time,temperature,pH and enzyme dosage on amino nitrogen content in the extact was studied.By the orthogonal test,the most optimal extraction conditions were as follows: the time was 2.5 h,the temperature was 45.0 ?,the pH value was9.0,enzyme dosage 14.0 mg/g.The DPPH clearance rate and NK cell activity were determined.The results showed that with the increase of the concentration,the DPPH clearance rate and NK cell activity increased.