不同物种乳氨基酸含量及组分的比较研究

为探讨不同物种乳氨基酸含量的差异及变化规律,本试验分别从北京、陕西、云南和青海等地区采集奶牛(高蛋白奶牛和低蛋白奶牛)、山羊、水牛和牦牛的乳样(各20个样品),乳样品经7.8 mol/L盐酸水解24 h后,采用氨基酸自动分析仪测定其中17种氨基酸含量,采用SAS 9.0和The Unscrambler 9.8软件分别对数据进行方差分析和主成分分析(PCA)。方差分析结果表明,牦牛乳中17种氨基酸含量均显著高于水牛乳、山羊乳、高蛋白奶牛乳和低蛋白奶牛乳(P<0.05);水牛乳中除苏氨酸、丝氨酸、缬氨酸和酪氨酸外,均显著高于山羊乳、高蛋白奶牛乳和低蛋白奶牛乳(P<0.05);山羊乳中苏氨酸、丝氨酸、缬氨酸、蛋氨酸、酪氨酸和苯丙氨酸含量均显著高于奶牛乳(P<0.05);除蛋氨酸外,高蛋白奶牛乳中氨基酸含量均显著高于低蛋白奶牛乳(P<0.05),4物种乳中总氨基酸含量均差异显著(P<0.05);PCA结果表明,水牛乳、牦牛乳、奶牛乳中氨基酸组成及含量相似,而山羊乳中由于较高含量的丝氨酸、苏氨酸、缬氨酸和酪氨酸使得其与水牛乳、牦牛乳、奶牛乳明显区分开。提示,不同物种乳中氨基酸含量差异显著,且具有一定的种属特性。

Comparative Study on the Content and Composition of Amino Acids in Milk from Different Species

The objective of this study was to investigate the regulation and variation of milk amino acids composition from different dairy animals. Milk samples from cows,goats,yaks and buffalos(n=20 for each species) were obtained from the local farm of Beijing,Shanxi,Yunnan and Qinghai province,respectively.Amino acids were extracted by hydrolyzed with 7.8 mol/L HCl for 24 h,and concentrations of amino acids were determined by high speed amino acid analyzer.Data was performed statistical analysis with the SAS 9.0 and principal component analysis with The Unscrambler 9.8 software. The results showed that concentrations of all tested amino acids in yak milk were significantly higher than those of buffalo,goat,high-protein and low-protein cow milk(P<0.05). Except for Thr,Ser,Val and Tyr,other amino acids of buffalo milk were significantly higher than those of goat,high-protein and low-protein cow milk(P<0.05).Thr,Ser,Val,Met,Phe and Tyr of goat milk were significantly higher than those of cow milk(P<0.05).Except for Met,amino acids in high-protein cow milk were significantly higher than low-protein cow milk(P<0.05). Amino acids of the cow,yak,buffalo and goat milk were significantly different(P<0.05).According to the PCA scores and loading plots,goat milk with Ser,Thr,Val and Tyr contents were different from the cow,buffalo and yak milk, which were grouped together. It was concluded that the different specials showed distinct amino acids profiles and had a certain species.