稻米蛋白提取工艺及其特性研究

Extraction and Characteristics of Water-soluble Proteins from Brown Rice (Oryza sativa L. subsp. japonica), Polished Rice and Rice Bran

以粳稻米为原料,分析其糙米、白米和米糠的营养成分及蛋白组成特点,研究提取条件对糙米、白米和米糠蛋白提取量的影响,并对这三种蛋白的溶解性及分子量分布特征进行比较。结果表明:糙米、白米中的蛋白均以谷蛋白为主,但糙米中谷蛋白含量比白米低4.78%,而清蛋白含量比白米高55.93%;糙米中清蛋白和球蛋白含量分别比米糠低77.22%、44.59%,但谷蛋白含量比米糠高47.00%。提取时间、温度及液料比对三种原料的蛋白提取量均有不同程度的影响,其中液料比是提取三种蛋白时最显著的影响因素(p<0.01);温度对白米蛋白提取影响显著(p<0.05)、对米糠蛋白极显著(p<0.01),而对糙米蛋白不显著;时间仅对提取白米蛋白有显著影响(p<0.05),对其他两种蛋白的提取没有明显作用。采用响应面法对提取条件进行优化,得到三个回归模型,经验证,用该模型可以预测稻米蛋白的提取量。稻米蛋白溶解性与SDS-PAGE电泳分析表明,糙米蛋白的溶解性及其蛋白分子量分布介于白米蛋白与米糠蛋白之间。

The brown rice, polished rice and rice bran of Oryza sativa L. subsp, japonica were analyzed for their proximate compositions and protein compositions. Soluble proteins were extracted from the brown rice, polished rice and defatted dee bran （our study indicated that removal of fat was favorable to dissolution of proteins） using deionized water （pH 8.5）, respectively, and response surface methodology was adopted to optimize the extraction of water-soluble proteins from the three materials based on one-factor-at-a-time experiments. In addition, the water-soluble proteins from different sources were subjected to analyses of solubility and molecular weight distribution. Protein composition analysis showed that both the brown rice and polished dee contained mainly glutelin, and the glutelin content in the former was 4.78% lower than that in the latter, while the former contained more albumin than latter by 55.93%; the contents of globulin and albumin in the brown rice were lower than those in the rice bran by 77.22% and 44.59%, respectively, while the glutelin content in the former was higher than that in the latter. All extraction duration, temperature, material/liquid ratio influenced yields of water-soluble proteins from these three materials to different extents - among the three factors, material/liquid ratio was the most significant one influencing all the extraction of water-soluble proteins from the three rice materials; temperature was a significant factor that influenced the extraction of polished rice water-soluble proteins （p 〈 0.05）, and for the extraction of rice bran water-soluble proteins, it was a extremely significant factor （p 〈 0.05）, while no significant influence was observe on the extraction of brown rice water-soluble proteins; extraction duration only presented significant influence on the extraction of polished rice water-soluble proteins （p 〈 0.05）. Three quadratic polynomial models for the extraction of water-soluble proteins from the three different materials were set up by response surface regression analysis. Predicted and actual values of extraction yield of water-soluble proteins were well fitted, indicating their validity was good. Solubility and SDS-PAGE analyses revealed that the solubility and molecular weight distribution of water-soluble proteins from brown rice were between those from polished rice and rice bran proteins.