| In this paper, the rice dreg,which was a by-product from rice starch syrup manufacture, was studied for prepatation methods, enzymatic modification and functional property of rice dreg protein(RDP). The aim is to find the best extraction process to obtain high purity RDP and improve its applicable properties to exploit a rice protein product. It provides gist and technological bases for the further development and utilization of rice resources.l.The results of determining the content of rice residue, such as protein, carbohydrte, fats and ash content showed that there is abundant of protein in rice dreg and it was a good resource for obtaining high purity protein. The analytical results indicated lower contents of every kind of proteins as Albumin, Globulin, Prolamin and Glutelin in rice dreg than in rice flour. The lique fying at high temperature leaded to the denaturation of protein and cut down the solubleness in alkali.2.Five methods, namely, alkaline extraction, water washing, protease extraction, enzymatic removal of sugars by cellulase, and by amylase, dual enzyme of celuulase:amylase extraction were used to prepare rice dreg protein from rice dregs. The last method gave the highest RDP extraction rate(90.25%) and purity(87.6%); and alkaline extraction gave the lowest RDP extraction rate(23.5%). The optimum extraction conditions of dual enzyme of amylase:celuulase extraction are liquid-solid ratio 1:10, amylase 8u/g; celuulase7 u/g, time 4h(amylasel.5h).3.Investigated effects of Alcalase, Neutrase, Trypsin, protamex and PaPain to hydrlysis degree of enzymatic hydrolyzed rice residues protein. It was found that alcalase was much better than the other fourth. The hydrolysis characters of rice residue protein were studied with Alcalase and the results are pH8.0, temperature45℃, enzyme in 28u/g, concentration of substrate 50mg/ml. The charaeteristics of rice dreg protein such as solubleness, emulsifiability and emulsification stabilities, whipability and whipabication stabilities were studied at different pH. The results showed that:at pH4.0-6.0 the solubleness of modification rice dreg protein is lowest and it is highest in alkaline environment; when the temperature lower than 80℃, the solubleness increaces as the increase of the temperature; but too high temperature can lead to protein denaturation and the solubleness decreases. In alkaline environment the modification rice dreg protein has good emulsifiability and whipability and they add with pH increasing, but the emulsification stabilities and whipabication stabilities changer a little. Water hiding capacity and oil hiding capacity were increased, respectively 1.45-1.68 times and 3.19-3.67 times.4.The rice dreg protein was modified by acidic deamidation. The results showed that the optimum conditions were as follows:0.4mol/L HCl solution at 85℃for 4 hours with 4% rice protein content. On these conditions, the deamidation was 63.53 percent and the degree of hydrolysis was 6.30 percent. Seven functional properties of rice dreg protein at this deamidation level including hydration, emulsifiability, emulsification stabilities, whipability, whipabication stabilities, water hiding capacity and oil hiding capacity were detected. In the deamidation range of 19.2%～63.53%, the results showed that the solubility and whipability were increased with the deamidation. The bigest solubility and whipability respestively are 70.5% and 57.6%. But the whipabication stabilities just has identical result and it decreases from 70.5% to 48.1%. In the deamidation range of 43.2%～51.6%, the emulsifiability and emulsification stabilities were better. And water hiding capacity and oil hiding capacity were changed a little as the addition of deamidation.
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