发芽对糙米蛋白质及氨基酸组成特性的影响

研究了发芽过程中糙米蛋白质和氨基酸含量和组成特性的变化,并与精米和糙米比较,评价了发芽糙米蛋白质的营养价值。结果表明,发芽可以增加糙米蛋白质、总氨基酸和必需氨基酸的含量,必需氨基酸指数提高。发芽过程中清蛋白和谷蛋白含量均呈上升趋势,球蛋白含量呈下降的趋势。除发芽24h外,醇溶蛋白的含量在整个发芽期间也呈现增加趋势,增加的蛋白质主要是谷蛋白。各发芽阶段糙米的必需氨基酸和总氨基酸的比值均大于55%。18种氨基酸中有12种氨基酸的含量在发芽24h最高。发芽后赖氨酸和苏氨酸的含量增加较明显,但仍是限制性氨基酸;丝氨酸、谷氨酸、精氨酸和组氨酸含量均有所增加。发芽24h时EAAI最大,与FAO/WHO模式相比,EAA组成模式更加合理。发芽可以提高糙米蛋白质的营养价值,改善籼稻米的品质,其中以发芽24h为宜。

Effects of Germination on Protein and Amino Acid Composition in Brown Rice

Polished rice,brown rice and germinated brown rice were selected to study the change of protein and amino acid composition,and to assess the protein nutrition value of germinated brown rice.Results: Germination increases the contents of crude protein,total amino acids,essential amino acid(EAA),and essential amino acid index(EAAI) of brown rice.The contents of albumin and glutelin increase while the content of globulin decreases during the germination.The content of prolamine keeps rising in the germination,in which the main rising amino acid is glutelin.During the process,the ratio of essential amino acid to total amino acids keeps over 55%.12 of 18 types of amino acid reach top level at the germination for 24h.The contents of lysine and threonine increase obviously after the germination though as limited amino acids yet.The contents of serine,glutamic acid,arginine,and histidine all increase more or less.EAAI reaches top value at the germination for 24h and has a more preferable EAA composition compared with FAO/WHO model.The nutritional value of protein and the quality of long-grain brown rice can be improved by germination and 24h is the proper germinating time.