不同品种的乳脂肪球的组成成分不同, 从而导致脂肪在乳中的存在形式和最终的乳品品质存在差异。 利用拉曼光谱测定黑白花牛乳、 水牛乳及牦牛乳中脂质球的脂质和脂肪酸成分, 比较不同品种牛乳的脂质组成差异。 结果显示, 牦牛乳的2 885/2 850 cm-1比值较高, 表明牦牛乳脂质球趋于形成结晶态脂肪球膜包裹流动态内核的结构。 与黑白花牛乳相比, 牦牛和水牛乳的1 655/1 443 cm-1比值较高, 表明黑白花牛乳的脂肪酸不饱和程度低于其他两种牛乳; 水牛乳小脂肪球的脂肪酸不饱和度高于牦牛乳, 大脂肪球的则低于牦牛乳。 综上可知, 用牦牛乳分离而得的稀奶油较其他牛乳难熔化, 搅拌耗时更长, 但形成的黄油更柔软; 而水牛乳由于脂肪球较大, 适用于奶油的加工和脂肪球膜的分离。

Different breeds of cows affect the form of fat exist in dairy products and the final functionality, which depended mainly on the composition of the milk fat globules(MFG). However, the relationship between the composition and breeds has not been illuminated. In our study, differences in the lipid content and fatty acid composition of native bovine, buffalo and yak MFG were investigated by confocal Raman spectroscopy. The research offers the possibility of acquisition and analysis of the Raman signal without disruption of the structure of fat globule. The results showed that yak MFG had a higher ratio of band intensities at 2 885/2 850 cm-1, indicating yak MFG tend to have a triglyceride core in a fluid state with a milk fat globule membrane in a crystalline state. The buffalo and yak MFG had a higher level of unsaturation compared to bovine MFG, shown by a higher ratio of band intensities at 1 655/1 744 cm-1. The results indicate that small MFG of buffalo is more unsaturated than yak, while the large MFG of buffalo is less unsaturated than the yak. Thus, selective use of cream with yak MFG would allow a harder and more costly churning process but lead to a softer butter. Buffalo milk which contains larger MFG is more suitable for cream and MFG membrane separation.