Study On The Preparation And Functional Properties Of Plant Protein Enzymatic Hydrolysis By Continuous Microwave Assisted Technique

Because the plant protein is rich in resource, large production, cheap price, and has unique functional properties and nutritional characteristics. Plant protein is often used as a food raw material ingredient or added base material. Due to some deficiencies of the plant protein limits its application in food industry, research shows that hydrolysis of protein is a good way. Enzymatic hydrolysis has great advantages, but conventional enzymatic hydrolysis time is very long. We found that enzymatic hydrolysis reaction in the assistance of microwave radiation can speed up the reaction rate. A laboratory scale continuous microwave reactor was designed, in this reactor the power of microwave radiation can be adjusted and the temperature can be controlled.In batch microwave condition, soybean protein isolates hydrolyzed by alkaline protease. Through single factor and orthogonal design experiments, the optimal microwave assisted hydrolysis condition is microwave temperature 60°C, microwave power 500 W, substrate concentration 6%, and enzyme substrate ratio 7%, reaction time 12 min. The content of peptide is 10.96 mg/mL, and has the greatest hydroxyl radical scavenging capacity. Water bath controlled trial found that protein 12 minute-hydrolysis under microwave radiation and protein 2 hour-hydrolysis under water bath has the same result.In continuous microwave condition, through single factor and orthogonal design experiments, the optimal microwave assisted alkaline protease hydrolysis condition for soybean protein isolates is microwave power 500 W, substrate concentration 4%, enzyme substrate ratio 9% , reaction time 15 min, and the content of peptide is 13.04 mg/mL. Water bath controlled trial found that protein 15 minute-hydrolysis under continuous microwave radiation and protein 1.5 hour-hydrolysis under water bath has the same result. Gel electrophoresis showed that hydrolysates molecular weight is less than 20000 Dalton, and is concentrated around 14400 Dalton.In batch microwave condition, through single factor experiments, the optimal microwave assisted alkaline protease hydrolysis condition for cottonseed meal is microwave temperature 60°C, microwave power 500 W, enzyme substrate ratio 5% , reaction time 15 min. The optimal microwave assisted Flavourzyme hydrolysis condition for cottonseed meal is microwave temperature 60°C, microwave power 600 W, enzyme substrate ratio 5% , reaction time 15 min. Reference to the above method, in continuous microwave condition, hydrolysates content of peptide is 13.32 mg/mL, is higher than the same condition in batch microwave radiation. Cottonseed meal after double enzymes hydrolysis , functional properties is improved. Oil absorption increased 50%, foaming increased 25.45%, emulsifying increased 28.62%, foam stability has greatly improved, only emulsion stability not have much change.