牦牛乳及乳制品、犏牛和黑白花奶牛乳的脂肪酸组成分析

用气相色谱 质谱联用仪(GC MS)对牦牛乳、黑白花奶牛乳、犏牛乳及牦牛乳制品（奶油、酥油、曲拉、酸奶）中的脂肪酸组成进行了测定。结果表明，牦牛乳中功能性脂肪酸，如共轭亚油酸（CLA）、亚油酸（LA）、α 亚麻酸（ALA）、γ 亚麻酸（GLA）占总脂肪酸的比重均显著高于犏牛乳和黑白花奶牛乳（P＜0.05）；犏牛乳中ω 6/ω 3 PUFA的比值（1.55）略高于牦牛乳（1.54），差异不显著（P＞0.05），但都在最佳膳食平衡比值范围内，黑白花奶牛乳中ω 6/ω 3多不饱和脂肪酸（PUFA）的比值（11.33）超过了推荐最佳比值。加工处理能够改变乳制品脂肪酸的构成，如牦牛乳奶油中检测出原奶中所不含的一种亚油酸（18:2Δ8c,11c）。酥油主要以不饱和脂肪酸（UFA）为主，而曲拉主要以饱和脂肪酸（SFA）为主，牦牛酸奶中没有检测到GLA。

Fatty acid components among yak milk and its dairy products,cattle-yak milk and cow milk

The composition of fatty acids in yak milk, cow milk, cattle yak milk and dairy products (yak butter, ghee, qula and yogurt ) were detected by GC MS. The results showed that the proportion of functional fatty acids, including conjugated linoleic acid (CLA), linoleic acid（LA）, alpha linolenic acid (ALA) and gamma linolenic acid (GLA), in yak milk were significantly higher than those in cattle yak milk and cow milk (P<0.05). The ratio of ω 6/ω 3 polyunsaturated fatty acids (PUFA) in pianniu milk (1.55) was slightly higher than that in yak milk (1.54), but no significant difference (P>0.05) between each other. The ratios of ω 6/ω 3 polyunsaturated fatty acids (PUFA) in cattle yak milk and yak milk were within the range of the best recommended prandial balance ratio. However, the ratio of ω 6/ω 3 polyunsaturated fatty acids (PUFA) in cow milk was above the best recommended range. Processing products of yak milk changed the nutrients composition. Linoleic acid (18:2Δ8c,11c), which did not exist in yak milk, was found in yak butter. The fatty acids in ghee were mainly unsaturated. But they were mainly saturated (SFA) in qula. Gamma linolenic acid (GLA) was not detected in yak yogurt.