A Study On Edible Quality Improvement Of Brown Rice

The composition of bran of the brown rice were studied,while the quality of brown rice was analyzed after improvement by enzyme in this dissertation.In the bran of brown rice,pericarp contains the highest dietary fiber,reaching to 30.91%,also abundance of fat nearly 21.32%,and starch just 9.69%;seed coat contains much fat,dietary fiber;aleurone layer contains the highest phytic acid of 7.98%;The sub-aleurone layer contains the highest protein, about 15.84%,starch is over 50% of its mass,and lowest of the phytic acid.From outer to inner in the brown rice bran,ash,fat and dietary fiber content become decreasing, protein and starch content increase.Ash,protein,fat,dietary fiber and phytic acid of rice decreased with the bran remove ratio increasing.The content of ash,protein,fat,dietary fiber and phytic acid of rice is less than that of the cortex. At the same pressure and time conditions,different degree of milling rice and bran were obtained by graded milling.The previous bran remove ratio were larger than behind.The pericarp and seed coat's structural force are weak, and aleurone layer,endosperm layer structural are strong in brown rice.The total bran remove ratio of change with times is y=-0.0533x2 +1.7454x-0.1271,regression coefficient R2 = 0.9988.Pectinase, xylanase,cellulase and mixed-enzyme was selected to improve edbile quality of the brown rice.Cellulase can be effectively decomposed cortex fibers of brown rice.The best technical parameters of the degration was gained though the mathematical analysis by means of response surface on the basis of the single-factor test.The optimal cellulase enzyme addition conditions were : enzyme concentration 1mg/ml,ratio of material to solvent 1:3.4,pH 5,temperature 49.7℃,time 118min . By cellulase treatment, brown rice's bran fibers decomposed effectively,fiber content is from 0.94% to 0.72%, lower by 22%.Through SEM observe brown rice epidermis,the fiber structure of bran was damaged after action, and then it had holes.Cooking characteristics of rice was tested , dry matter of rice water ,starch-iodine- blue of the enzyme-improved brown rice(EIBR) water were higher than brown rice,water absorption,swelling volume and the pH value was between brown rice and milled rice,hardness/adhesion of EIBR was significantly less than brown rice, which were measured by texture analyzer. These indicates that enzymolysis treatment improved the eating quality . Micro-nutrient nutrient composition shows thatγ-aminobutyric acid content is 2.6 and 10.3 times to brown rice and milled rice.VB1,VB2,nicotinic acid,calcium,iron contents are 2.62,1.54,1.48,1.2 and 3.26 times to milled rice respectively.The reasults of the dynamic rheometer shows that the initial gelatinization temperature of EIBR is 57.6℃,the highest gelatinization temperature is 74.4℃,the initial gelatinization temperature is close to milled rice, and lower than the brown rice for about 5℃, the highest gelatinization temperature is slightly lower than the brown rice.Dried by microwave digestion, the fatty acid value of EIBR is less than that in hot air drying, and fatty acids value is also less in the vacuum packing compared with ordinary package.