Studies On Preparation Of High Quality Rice Protein By Two-enzyme Method

Rice protein is a kind of high quality plant protein for its composition of amino acid is balanced and equitable, besides, it has high BV and PER value and low allergy, so it's suitable for the infants and the special people to diet. RP has broad market potential. The reports on preparation of RP by protease method are very common, but research on debitttering of protein product is quite rare. The paper had proposed a new preparation technology of high quality RP from raw material of rice dreg. Meanwhile, the process design and preliminary cost accounting were carried on.The process carried out and the conclusion obtained were as follows:1. The assurance of technology conditions for pretreatment of rice dregThe pretreatment conditions of rice dreg were assured by the indexes of protein content and yield : the raw material was extracted in petroleum ether for 2 hours with the 10 times/h siphonal frequency; the temperature of desugar by water was 80℃and the ratio of liquid versus solid was 3:1, the wash time was 1 hour and the material was washed once. The protein content was risen from 63.23% to 68.25% by degrease treatment, it was further promoted to 71.33% by desugar treatment.2. The assurance of optimized conditions for protease hydrolyzeWe carried on the experiments with the acid protease,neutral protease and alkali protease separately and found that the neutral protease was the best choice. The production of trypsin was the best among several neutral protease by the indexes of protein content and yield. The optimized hydrolysis conditions of trypsin were as follows: enzyme/substrate 0.2%, pH value 7.4±0.2, hydrolysis time 14 hours and temperature 40～45℃.3. Studies on debittering of protein productsWe come to thinking of using excision enzyme to get ride of bitter by considering the reasons of bitter generates. We carried on the experiments by treating the trypsin as the main enzyme and the high efficient protease as assist enzyme, the product of the protein content was slightly promoted and the degree of hydrolysis (DH) was 3 times of the product without adding the high efficient protease. We got the technics of two-enzyme method by three indexes of protein content,yield and DH as follows: material/liquid 1:5, enzyme/substrate of trypsin 0.2%, enzyme/substrate of high efficient protease 0.1%, the adding time of high efficient protease was after 4～5 hours of trypsin, the total reaction time was 14 hours, pH value were 7.4±0.2(trypsin)and 7.0～7.2(high efficient protease) separately, reaction temperature was 40～45℃.The studying results of process show that two-enzyme method of rice protein preparation has the following advantages: the technology is concise and reasonable and without the emission of waste water, low air pollution. The product has good dissolve character and can be easily absorbed, in addition, its composition of amino acid is reasonable and its industrial manufacture has considerable benefits, so the new process has vast market prospect.