玉米肽的制备、特性及活性研究

【作者】 李艳丽；

【导师】 陈光；

【作者基本信息】 吉林农业大学 ， 生物物理学， 2003， 硕士

【摘要】 玉米蛋白粉是玉米湿法生产淀粉的主要副产物之一。它含有60％以上的蛋白质，约68％的蛋白质为醇溶蛋白，难溶于水。其中必需氨基酸含量高于大豆和小麦，但赖氨酸和色氨酸含量较低，限制了其在食品领域的应用。目前，多数淀粉厂家把其低价当作饲料原料出售。随着科学技术的发展，玉米蛋白作为饲料将不能满足于淀粉工业副产品深加工的要求。面对当今世界蛋白质资源严重短缺现状，只有运用高新技术对玉米蛋白粉进行深加工，才能提高其附加值，提高企业的经济效益，从而提高对玉米资源的综合利用率。 现代营养学研究发现，人类摄食的蛋白质经消化酶作用后，大多数是以低肽而不是氨基酸形式吸收的，且组成这些低肽的氨基酸不一定是必需氨基酸。这些低肽除了具有易消化吸收性质外，还具有许多良好的功能特性和生理活性，可以被广泛地应用到食品领域中去。 玉米肽是玉米蛋白质经酶水解、精制后所得到的短肽混合物。日本在此领域的研究处于世界领先位置，日本、西欧、美国的玉米肽类食品早已上市。我国对玉米肽的研究还处于起步阶段，仅限于理论报道，玉米肽食品几乎空白。且一般均采用单一酶进行水解，对水解后的玉米肽的理化性质研究较多，对其生物活性研究较少。 本文运用混合蛋白酶对玉米肽制备进行了探索。分别运用单因素试验和正交试验方法确定了两种酶的最佳水解条件。对两种酶单独水解以及双酶共同水解制备玉米肽进行了比较研究，最终确定以双酶分步水解法制备玉米肽的最佳酶解条件。即：温度为55℃，底物浓度为5％，pH分别为两种酶最适(碱性蛋白酶为8.5，木瓜蛋白酶为7.5)，先以4％的酶与底物比的比例加碱性蛋白酶，水解1.5h后，再以3.5％的酶与底物比加木瓜蛋白酶，水解1.5h。此时水解液中氮溶指数X和水解度DH分别达到81.06％和80.97％。分析了各因素对水解效果的影响。对水解液进行了脱苦、脱色、减压浓缩、冷冻干燥等精制步骤研究，确定了干粉玉米肽制备的工艺流程及各参数。最终得到得率达65％、含量在75％左右的干粉玉米肽。对玉米肽的组成、理化性质及生理活性进行了研究。表明：玉米肽富含谷氨酸和亮氨酸，大部分肽分子量分布在5000Da以下。极大改善了玉米蛋白粉的水不溶性，具有溶解性不受pH值影响及高浓度低粘度等特性。还具有众多的生理活性：抗氧化、促进酵母发酵活性，还具有抗疲劳，促进乙醇代谢活性，吉林农业大学硕士学位论文玉米肤的制备、特性及活性研究且有量效关系。 运用酶工程技术对玉米蛋白粉进行深加工制得新一代功能保健因子一一玉米肤，弥补了玉米蛋白粉难溶于水和氨基酸分布不平衡的特性，良好的溶解性使玉米肤表现出许多良好的性质及生理活性，将作为保健食品的原料而广泛应用于食品及医药领域。随着人们崇尚保健意识的增强，玉米肤的开发必将会有广阔的市场前景。更多还原

【Abstract】 Corn protein powder is the main one of by-products that produce the starch in corn wet-milling process. It implies more than 60% protein and the major protein fractions are zein (68%). It is insoluble in water. The content of essential amino acids is higher than soybean and wheat. But the content of Lys and Trp is low. These drawbacks limit its application to the food fields. Now, most of starches factories regard it as the animal feed to sell in low price. Facing lack protein resources in the world , the corn protein is used as the animal feed can not satisfied with the requirement that deal with the by-products of starch industries-corn protein powder. Only using modern high and new techniques to deal with the corn protein powder deeply, we can increase its additional value and increase the economic benefit of the business. Thus it will improve total utilization rate of the corn resources.The modern nutrition research discovers that the protein is digested and absorbed mainly in low peptide but not in amino acids after enzymes hydrolyzing. And the amino acids what is consisted of low peptide may not be essential amino acids. In additional to having the easily absorption characteristic, these low peptide still have many good functions characteristic and the physiological activity. They can be used widely in the food field.Corn peptide is the mixture of short peptides that the corn protein is hydrolyzed by enzymes and again is refined. Japan takes the first place in the field of corn peptides’ research. Corn peptide food has appeared on market early. In our country, this field still is placed in the starting stage and only has theories reports. There are few corn peptide products in the market. Corn protein is hydrolyzed only by one enzyme in their researches and properties of corn peptide are researched more but the physiological activity studies are researched less.Two kinds of protein enzymes have been used to hydrolyze corn protein to produce corn peptide in this article. Through the single factor experiments and orthogonal test, the optimum hydrolyzing conditions have been determined: Temperature is 55 癈 ,pH value is two enzymes’ optimum pH value(pH of an alkaline protease is 8.5 and pH value of pepsin is 7.5). After hydrolyzing 1.5 hours adding alkaline protease with the 4% enzyme concentration, corn protein powder iscontinuously hydrolyzed 1.5 hours again adding pepsin with 3.5% enzyme concentration. In this condition Nitrogen Solubility Index (X) and degree of hydrolysis (DH) are respectively 81.06% and 80.97%. The effect of factors on hydrolysis has been analyzed. Then the hydrolysis is refined by removing bitterness, color, decompression condensing and ice drying and the process parameters to produce corn peptide powder has been determined. At last corn peptide powder is gained and its gotten rate is about 65% and protein content is about 75%. The constitution, physical and chemical properties and physiological function of corn peptide powder are studied. The results show that the corn peptide is abundant in Glu and Leu and most of molecular weight distributions is below about 5000Da. The solubility in water is improved and is not changeable with the changing of pH. It has low viscosity in high concentration. Further more corn peptide has many physiological activity: anti-oxidation promoting yeast fermentation activity anti-fatigue, promoting the alcohol metabolism activity and has quantity and effect connection.Using enzyme-engineering techniques, corn protein powder is produced deeply into corn peptide what is a new generation function factor. Corn peptide makes up the drawbacks of corn protein such as unbalanced amino acids constitution and insolubility in water. Better solubility can make corn peptide present many good characteristic and physiological activity at the same time. It will be extensively applied to the raw material of heath food. As people’s consciousness of health is building up, the development of corn peptide will have the vast market foreground necessarily.更多还原