Study On Modification Of Rice Protein Degradation And Foaming Performance

Rice residue, by-product of rice starch sugar enterprises, is a kind of high-qualityplant protein resources, which protein content reaches60%. Taking rice residue as rawmaterial and foaming property as the core, the main research contents and results wereas follows.Extraction methods and conditions of rice protein were optimized by single factorexperiments. The optimal condition was that rice milk sifting200mesh sieve, addingfive times deionized water, then using0.1mol/L NaOH to adjust the pH to10.00. At40℃, the mixture was stirring for1h at10000rpm using a water bath, then, the supernatepH was adjusted to isoelectric point with1mol/L HCl, after centrifuged at10000rpmfor10min, the sediment was centrifuged again after three times wash, rice protein wasobtained from freeze drying. After separation and purification, the protein content ofrice was88.29%. The solubility of rice protein was lowest at pH4.0, however,solubility is much higher while pH under4.0or above5.0. Water and oil holdingcapacity of rice protein is1.17g/g and6.47g/g, respectively. According to the riceprotein SDS-PAGE electrophoresis, rice protein molecular weight is about42000、31000、27300、19200、15600、12600D.Alkaline hydrolysis and enzymatic are two ways of modification of the rice residueprotein. Optimum technological conditions was pH10.50, the concentration of theprotein (7.0%), reaction temperature of55℃. Alkaline protease enzyme hydrolysis ofrice residue protein, the best process conditions was pH8.50, the protein concentrationof6.0%, the enzymatic capacity of2.0%, the reaction temperature of55℃and the timeof90min. Modified rice residue protein foaming ability and foam stability werecompared before modification, significantly, foamability reached386%, foamingstability at64%. Rice, rice residue, enzymolysis liquid for electron microscope scanning,found that the rice grain surface is relatively full density continuous structure, smoothsurface and no pore size particles of the sphere. After rice residue desugaring anddegreasing, surface structure transfers to a smooth honeycomb structure, and exhibitsthe large diameter hole. The processed enzymatic hydrolysis showed a lamellarstructure after drying, whose network structure was completely destroyed.Rice residue liquid protease solution was for distribution. Foaming for index, theprotease hydrolysis of rice residue protein compound with the best combination wasadding NaCl (1.32g), glucose (1.44g), Na2CO3(1.32g), Na2SO3(0.72g), respectively.The measured foam volume is410mL. According to solubility, protease hydrolysis ofrice residue protein compound with the best combination was adding NaCl (1.44g),glucose (1.44g), Na2CO3(1.44g), Na2SO3(0.60g), respectively. The measuredsolubility is0.514.