Department of Food Science, Aarhus University, Blichers Allé 20, PO Box 50, DK-8830, Tjele, Denmark.
J Sci Food Agric. 2013 May;93(7):1620-5. doi: 10.1002/jsfa.5934. Epub 2012 Nov 8.
The melting behaviour and fatty acid composition of cream from a total of 33 cows from four farms were analysed. Multivariate data analysis was used to identify the fatty acids that contributed most to the melting points and to differentiate between creams from different practical feeding regimes.
It was demonstrated that the melting point of the medium melting fraction of milk fat was positively correlated with palmitic acid (C16:0), whereas it was negatively correlated with oleic acid (C18:1 cis9), conjugated linoleic acid (CLA cis9 trans11), vaccenic acid (C18:1 trans11), elaic acid (C18:1 trans9) and myristoleic acid (C14:1). The melting points of the high melting fractions could not be related to the fatty acid composition. Addition of palmitic acid-based fat supplement to the feeding ration in combination with a lower forage intake increased the amount of C16:0 and palmitoleic acid (C16:1) in milk fat, whereas it decreased the amount of stearic acid (C18:0) and C18:1 trans fatty acid. Average data on the melting behaviour of cream separated the farms into two groups where the main differences in feeding were the amounts of maize silage and rapeseed cake used.
Multivariate analysis of data from individual cows identified the most relevant fatty acids contributing to the melting point of the medium melting fraction of cream. The fatty acid composition of milk fat could differentiate cream from different feeding strategies; however, owing to individual cow variation, it was not possible to extract clear correlations between feeding regime and melting behaviour of cream.
对来自四个农场的 33 头奶牛的奶油的融化行为和脂肪酸组成进行了分析。使用多元数据分析确定了对熔点贡献最大的脂肪酸，并区分了不同实际饲养方案的奶油。
结果表明，牛奶脂肪中中等熔点部分的熔点与棕榈酸（C16:0）呈正相关，而与油酸（C18:1 cis9）、共轭亚油酸（CLA cis9 trans11）、反式 11-十八碳烯酸（vaccenic acid，C18:1 trans11）、反式 9-十八碳烯酸（elaic acid，C18:1 trans9）和豆蔻酸（myristoleic acid，C14:1）呈负相关。高熔点部分的熔点与脂肪酸组成无关。在饲养日粮中添加基于棕榈酸的脂肪补充剂并减少饲料摄入量会增加牛奶脂肪中 C16:0 和棕榈油酸（C16:1）的含量，而减少硬脂酸（C18:0）和 C18:1 反式脂肪酸的含量。奶油融化行为的平均数据将农场分为两组，主要的饲养差异在于使用的玉米青贮和油菜籽饼的数量。
对个体奶牛数据的多元分析确定了对奶油中等熔点部分熔点贡献最大的相关脂肪酸。牛奶脂肪的脂肪酸组成可以区分不同饲养策略的奶油；然而，由于个体奶牛的变化，不可能从饲养方式和奶油融化行为之间提取出明确的相关性。
