Studies On Enzymatic Process Of Preparing Rice Bran Protein Isolate

The research was conducted on enzyme hydrolysis in preparing protein from rice bran. Several enzymes were selected and hydrolysis technique was optimized. The functional properties of rice bran protein were primary studied.The material was produced by Wu Chang Rice Manufactory. The composition of rice bran was that protein: 12.28%, fat:20.01%% cellulose: 23.95%, starch: 15.44%, moisture: 10.78%.Enzyme is a kind of protein, so the suitable method was selected by testing, which can effectively inactivate enzyme, it was that pH:4.0, temperature:50 C, time:3h.As pI of rice bran protein was not reported by references. It was determined by testing protein concentration at different pH. The result of rice bran protein pI was pH=4.6.Different enzyme has different hydrolysis process. The kind of broken kernels enzymes and proteases were selected in the process of preparing rice bran protein. Comparing nitrogen reclaim and degree of hydrolysis, cellulase and protamex were fitted.Cellulase , protamex, phytase were differently used to hydrolysis rice bran under the optimum temperature and pH, the time and substrate concentration were under the same condition. Single factor was adopted to determine optimum enzyme concentration of every enzyme, and the result showed nitrogen reclaim of single enzyme was not high under the optimum condition. At the same time, in the ingredient test the range of every enzyme concentration was determined by above result.In the ingredient test, the range of single enzyme concentration was transformed to the percent of total. Then revolving, orthogonal and tropical design of the second power of two factors was adopted to study the percent of cellulase , protamex and phytase. Under the condition of substrate concentration 15%, temperature 45 C,pH=5.5,time 2h and enzyme concentration 2%, the model was established: y =70.76+1.58X1+2.40X2-0.9X12+1.28X1X2y: nitrogen reclaim X1: cellulase concentration X2: protamex concentrationF-test was used to verity the model. The result indicated the testing goodness of it. The result of frequency analysis and variable transform showed that the optimum enzyme proportion was that cellulase 65.84%; protamex 18.52%; phytase 15.64%.The orthogonal experiment and single factor test were used to determined the optimum condition of multiple enzyme, it was substrate concentration20%, temperature 45"C,pH=5.5,time 2h, enzyme concentration 4%.Emulsion capacity, foaming capacity and viscosity of rice bran protein were tested andwere compared to soybean protein. The results were that emulsion capacity of rice bran protein was higher than soybean protein, and foaming capacity and viscosity were lower than it.Postgraduate: Wang Xuefei Major: Food Science Supervisor: Associate Prof Yu Guoping...