Research On The Key Technology In The Value-added Utilization Of Rice Bran

As an important by-product in the process of rice processing, rice bran accounts for 5-6% wt.% of rice, but enriches about 80% nutrients of rice. The amount of the resource is huge in our country and it lies in world's top level. But it is mainly used as fodder in China, its effective utilization rate is less than 10%, resulting in a huge waste of resources. In order to improve the utilization of rice bran resources effectively, and realize the comprehensive utilization of rice bran, enzymatic hydrolysis of rice bran starch and enzymatic hydrolysis of rice bran protein were studied in this paper. Due to the relatively high content of starch in rice bran, hydrolysis of starch to glucose was studied firstly, so that protein content in rice bran residue will increase relatively, then extracted the rice bran protein. This study can achieve classification utilization of rice bran resource, and improve the effective utilization rate of the rice bran resource.In this paper, the rice bran starch was hydrolyzed by double enzyme method(amylase+glucoamylase) for preparation of fermented molasses. This method mainly includes the technology of paste, liquefaction, glycosylation and so on. In this paper, the gelatinization and liquefaction was carried out at the same time, that is, one step method of gelatinization and liquefaction. The technology of liquefaction and glycosylation were studied and optimized respectively.Through the study of the single factor experiment of liquefaction process, examined the influence of enzyme dosage, mash concentration, pH and temperature on liquefaction process. On the basis of single factor experiment, the liquefaction technology of rice bran starch was further optimized by the Box-Behnken of Design Expert 8.0.6 software, and the optimal liquefaction process conditions were obtained: 0.11% enzyme dosage, mash concentration 25%, pH=6.0, temperature 88?. Under this conditions, the liquefied DX(glucose value) average-value was 6.54%.Moreover, based on the iquefaction of rice bran starch, the saccharification process of liquefied was studied. Through the single factor experiment, examined the influence of enzyme dosage, temperature, pH on Saccharification process. The optimal conditions of saccharification process were obtained as follows: 0.03% dosage of enzyme, temperature 60°C, pH=4.5. Under the optimal conditions, the saccharification DX average was about 97% eventually. HPLC analysis showed that the content of glucose in saccharifying solution accounted for more than 99%, almost no two sugar and three sugar.After the hydrolysis of starch, rice bran protein was extracted from rice bran residue by double enzyme method(pretreatment enzyme+protease). First of all, pretreatment enzyme and protease species were screened to obtain the optimum enzyme composition. The optimum enzyme composition was complex cellulose(Celluclast 1.5L) and alkaline proteases(Alcalase 2.4L FG). Then the two enzymes were studied and optimized. Through the single factor experiment of composite cellulose, the optimized technological conditions were as followes: 0.2% of enzyme dosage, 60? temperature, pH=6.0, 12% of mash concentration. On this basis, the extraction of rice bran protein was further studied using alkaline protease. Through the single factor experiment of alkaline protease, the effects of temperature, pH, enzyme dosage on the extraction rate of protein was studied. On the basis of single factor experiment, the process of extracting rice bran protein by alkaline protease was optimized by response surface methodology. The optimal process conditions were obtained as follows: temperature 88?, pH=8.5, 2.11% dosage of enzyme. Under the conditions, the average value of the rice bran protein extraction rate was 85.3%. By SDS-polyacrylamide gel electrophoresis, the molecular weight of the extracted rice bran protein was lower than 25 kDa.Through the study on the hydrolysis of rice bran and the extraction technology of rice bran protein, this paper obtained the optimal conditions, in order to provide theoretical basis for the production of rice bran starch syrup and protein. thus realizing the high value and comprehensive utilization of rice bran resource.