罗非鱼-豆粕共沉淀蛋白的提取及溶解性、氨基酸组成分析

摘要

以罗非鱼和脱脂豆粕为原料,将两者按不同质量比(1∶0、1∶1、1∶2、2∶1和0∶1,以干基计)混合,采用pH调节法提取罗非鱼-豆粕共沉淀蛋白,冷冻干燥制备罗非鱼分离蛋白(FPI)、共沉淀蛋白(CoPP-1∶1、CoPP-1∶2、CoPP-2∶1)和大豆分离蛋白(SPI)等18种蛋白粉,分析了其基本成分、溶解性、白度及氨基酸组成.结果表明,共沉淀蛋白粉的粗蛋白含量均高于80％,脂肪含量低于1.07％,高于或者接近FPI和SPI中粗蛋白和脂肪;共沉淀蛋白在pH 4.0～6.0范围内溶解性较差,而pH值低于4.0或高于6.0时,溶解度提高,且在极端酸碱pH范围内溶解度达到最大;比较而言,CoPP-1∶1和CoPP-1∶2在pH 7.0～8.0时溶解度高于CoPP-2∶1和FPI,但低于SPI的水溶性,蛋白粉的白度较好,表明CoPP-1∶1和CoPP-1∶2更接近SPI的蛋白组成,SPI主要由水溶性球蛋白组成,在水中的溶解性较高;共沉淀蛋白的必需氨基酸种类齐全,占总氨基酸的比例约42％左右,属于优质蛋白质.因此,pH调节法可用于提取蛋白含量高和营养价值高的共沉淀蛋白.%Co-precipitation protein was prepared from Tilapia muscle and defatted soybean meal by pH-shifting at the different mass ratio of 1∶0,1∶ 1,1∶2,2∶1 and 0∶1 (drying basis).Tilapia protein isolate (FPI),co-precipitation protein (CoPP-1 ∶ 1,CoPP-1∶ 2,CoPP-2∶1) and soybean protein isolate (SPI) of 18 kinds of protein powder were prepared by Freeze drying.The basic components,solubility,whiteness and amino acid composition were analyzed.The results showed that the content of the crude protein,and fat of co-precipitation protein was above 80％,less than 1.07％,which was more than or near to the crude protein,and fat content of FPI and SPI.The solubility of co-precipitation protein was poor at pH 4.0-6.0,but increased when pH below 4.0 or above 6.0,and reached the maximum at the extreme pH environment.Relatively,the solubility of CoPP-1 ∶ 1 and CoPP-1 ∶ 2 at pH 7.0-8.0 was higher than that of CoPP-2∶1 and FPI,but both of them were lower than the solubility of SPI in water and the whiteness of co-precipitation protein was better.The results showed that the composition of CoPP-1 ∶ 1 and CoPP-1 ∶ 2 are closer to SPI.SPI mainly consists of water soluble globulin,and has higher solubility in water.The co-precipitation protein has completed essential amino acid,and the total essential amino acids are about 42 percent of total amino acids,which belongs to high quality protein.The use of pH-shifting method can extract high protein content and high nutritional value of co-precipitation protein.