Studies On Extraction Of Wine Less Protein Concentration By Enzyme

In order to make full use of the protein resource in rice wine grains (RWG), theextraction technology of protein from RWG was investigated. Then protein extractedby hydrolysis was compared with the one by alkali solution in some physicochemicalproperties. The main results were listed below:(1) The optimum conditions of washing were: temperature 60℃, the ratio of stuffto water was 1:6, washing 30 minutes. Under these conditions, concentration ofprotein in washed grains was about 35.71%. Based on pre-trials and optimumconditions for cellulase, the de-cellulase technology was confirmed as follows: theratio of stuff to water was 1:10, enzyme dosage [E]/[S]= 28U/g, pH 5, reaction time30 minutes, temperature 50℃.(2) Through single factor experiment and Orthogonal experiment, the conditions forenzymic extraction of protein were optimized: enzyme dosage [E]/[S]= 2000U/g, the ratioof stuff to water was 1:8, pH 10, reaction time 3h, temperature 50℃. Under theseconditions, the protein recovery was 74.42%.(3) Compared with extraction by alcalase, Orthogonal experiment results showed theoptimum conditions for extraction by alkali solution: the ratio of stuff to water was 1:8, pH11, reaction time 3h, temperature 50℃or the ratio of stuff to water was 1:8, pH 11,reaction time 4h, temperature 45℃.Under these conditions, the protein recovery wasabout 67%.(4) A Method of combination design of quadratic regression rotation was used toanalyze protein extraction from RWG by alcalase. The result suggested that X₁,X₂,X₃,X₄,X₁²,X₁X₃,X₂X₃,X₂X₄,X₃² were significant factors. After excluding theinsignificant ones, a model equation was obtained:Y=74.19+1.07X₁-0.64X₂-1.05X₃+1.95X₄-1.24X₁²+0.92X₁X₃-2.34X₂X₃+1.51X₂X₄-0.51X₃²(5) The predigested protein was analyzed Using SDS-PAGE. The result suggestedthe molecular weight of most extracts by alcalase, which had a good solubility, was below 4.1KDa.On the other hand, the molecular weight of extraction by alkali Solutionranged from 20KDa to 35KDa, and the solubility was low. The protein extracted by bothalcalase and alkali solution was not good at foaming and emulsification. The foaming propertyof protein were 43% and 27%, the emulsification property were 50% and 13% for proteinsextracted with enzymic and alkali methods respectively.