【作者】 奚海燕；

【导师】 张晖；

【作者基本信息】 江南大学 ， 粮食油脂与植物蛋白工程， 2008， 硕士

【摘要】 本论文以粳米为原料,对大米蛋白的提取工艺、蛋白的功能特性和改性等进行了系统的研究,旨在通过改善大米蛋白的功能性质,开发一种大米蛋白产品,为稻米资源的深度开发和综合利用提供理论依据和技术基础。其主要研究结果如下:碱酶法提取大米水解蛋白的最佳工艺条件为:碱性蛋白酶在58℃,pH值8.5,料液比1:9,加酶量为1000 U/g米粉条件下提取4 h。在此工艺条件下,大米蛋白提取率达到70.50%,大米蛋白纯度为66.53%。分别采用物理-酶法,双酶法及碱酶分步法三种复合方法对大米蛋白提取工艺进行研究,结果表明三种复合方法均能提高大米蛋白提取率,其中碱酶分步法在提高大米蛋白提取率及纯度上效果显著。确定碱酶分步提取大米蛋白最佳工艺条件为:碱提,pH11.0,温度50℃,时间3 h,料液比1:8;酶提,加酶量750 U/g米粉,时间2 h,pH8.5,料液比1:9,温度55℃。在此条件下,大米蛋白的提取率达到90.21%,纯度达到83.34%。研究了pH值对大米蛋白溶解性、乳化特性、起泡性及起泡稳定性的影响,并对碱提大米蛋白和酶提大米蛋白的功能性质进行比较。最后采用碱性蛋白酶对碱提大米蛋白进行改性研究。确定南宁碱性蛋白酶最佳改性条件:加酶量5000 u/g蛋白,pH9.5,温度55℃和酶解时间2 h,得到大米蛋白溶出率为85.45%。对不同水解度条件下的大米蛋白的功能性质进行比较。结果表明DH为8%的大米蛋白酶解物具有良好的溶解性、乳化和起泡特性,随着DH的继续增大,蛋白的过度水解导致乳化和起泡性均有不同程度的降低。但其氨基酸组成无明显变化。同时对水解过程中蛋白酶的分配方式进行探讨。实验结果显示当加入较多的蛋白酶或随着反应时间的延长,分配于已溶蛋白水解的酶量比例较高。并在此基础上研究了TGase对DH16%大米蛋白水解液功能性质的影响。更多还原

【Abstract】 In this paper, the extraction process, functional property and modification of japonica rice protein are studied. The aim is to improve the functional property and exploit a rice protein product. It provides gist and technological bases for the further development and utilization of rice resources. The main results are as follows:The optimum extraction conditions of Alkali-protease is as follows: temperature 58℃, pH 8.5, the material-liquid ratio 9:1, enzyme/substrate1000 U/g,the time 4h. The ratio of extraction can reach 70.5%, and the purity can reach 66.53%.The rice protein extraction by the physical-Enzymatic, dual enzyme and the two-step method of alkaline–enzyme are studied. The results show that the three methods can increase the extraction rate of rice protein, and the effect of the two-step method of alkaline-enzyme is significant. The optimum extraction conditions of the two-step method of alkaline-enzyme: alkaline extraction, pH11.0, temperature50℃, time 3 h and the material-liquid ratio:8:1; alkali-proteased extraction, temperature: 55℃, pH:8.5, the material-liquid ratio:9:1, enzyme/substrate:750 U/g, the time 2 h. The ratio of extraction can reach 90.21%, and the purity can reach 83.34%.The effect of pH on solubility, emulsifying properties, and foaming properties of two rice protein( alkaline and protease ) are studied.The modification of rice protein by alkaline Nanning alkaline protease is researched. The best modified conditions: enzyme in5000 u/g, pH9.5, temperature 55℃and hydrolysis time 2 h and rice protein has the dissolution rate of 85.45%.The rice protein functional properties of different hydrolysi conditions, are compared. The results show that 8% of the DH for the rice protein has good solubility, emulsifying and foaming properties. With the DH increase, rice protein hydrolysis emulsification and excessive foaming characteristics were decreased in different degrees. And the amino acid compositions have no significant changes. The experimental results show that the relationship between solubility and hydrolysis in different hydrolysis conditions prove when joined with the more protease or reaction time,the distribution in the soluble protein hydrolysis has a higher proportion of the protease.And on the basis of modification by protease, the effect of TGase on rice protein of 16% DH was studied.更多还原