牛初乳与牛常乳中游离氨基酸和不溶性蛋白质氨基酸对比研究

Comparative Study of Free Amino Acids and Insoluble-Proteome Amino Acids in Bovine Colostrum and Mature Milk

牛乳是生产婴幼儿配方乳粉时首要选择的原料乳,氨基酸是构成牛乳蛋白质的结构单位,按照分布区域的不同,分为游离氨基酸和不溶性蛋白质氨基酸两类。以产后0~7 d的牛初乳和15 d~6个月的牛常乳为原料,对牛乳中不同结构域的氨基酸种类及含量进行对比分析。结果表明:9种游离必需氨基酸在牛初乳和牛常乳中均被检测到,分别有8种和7种游离非必需氨基酸在牛初乳和牛常乳中被检测到,其中,牛初乳中8种必需氨基酸、4种非必需氨基酸含量均显著高于牛常乳(P<0.05);在不溶性蛋白质氨基酸中,牛初乳和牛常乳中均含有8种必需氨基酸和10种非必需氨基酸,其中,牛初乳中苏氨酸、精氨酸、丝氨酸、半胱氨酸、丙氨酸含量显著高于牛常乳(P<0.05),而牛常乳中赖氨酸含量显著高于牛初乳(P<0.05)。

Bovine milk is considered as the raw milk of choice for the production of infant formula.Amino acids in bovine milk,the structural units that make up milk proteins are classified into two groups:free and insoluble-proteome amino acids,which are distributed in different regions(structural domains).In this experiment,we collected bovine colostrum at 0–7 days postpartum and mature milk at 15 days-6 months postpartum for comparative analysis of the insoluble-proteome and free amino acids in them.The results indicated that 9 essential free amino acids and 7 non-essential free amino acids were detected in both milks.Additionally,another non-essential free amino acid was found in bovine colostrum.Among these,8 essential and 4 non-essential amino acids were found to be significantly more abundant in bovine colostrum than in mature milk(P<0.05).Among the insoluble-proteome amino acids,8 essential amino acids and 10 non-essential amino acids were detected simultaneously in both milks.Moreover,the levels of threonine,arginine,serine,cysteine,alanine in bovine colostrum were significantly higher than in mature milk(P<0.05),while the level of lysine was significantly lower than in mature milk(P<0.05).