Lu Jing, Pickova Jana, Vázquez-Gutiérrez José L, Langton Maud
Department of Molecular Sciences, Swedish University of Agricultural Sciences, PO Box 7015, SE-75007 Uppsala, Sweden.
Food Chem. 2018 Jan 15;239:848-857. doi: 10.1016/j.foodchem.2017.07.018. Epub 2017 Jul 6.
To investigate the effects of seasonal variations and processing on cow milk fat, raw milk collected in six individual months and corresponding ultra high temperature (UHT) milk were analyzed. Similar seasonal variations in lipid classes and fatty acid composition were found in raw and UHT milk. Under commercial processing, lipid content was standardized to approximately 1.5% in UHT milk. Decreased diameter of fat droplets (around 1µm) and thinner globule membranes were observed, as revealed using confocal laser scanning microscopy (CLSM). The distribution of lipid classes was modified with a decreased proportion of triacylglycerol accompanied by the increase of phospholipids and free fatty acids. Saturated fatty acids C12:0 and C14:0, trans-fatty acids including conjugated linoleic acid (CLA), polyunsaturated fatty acids C18:2(n-6) and C18:3(n-3), showed increased proportions in UHT milk. These results provide an indication of the effect of UHT processing on milk lipid properties.
为研究季节变化和加工对牛奶脂肪的影响，分析了在六个不同月份采集的原料乳以及相应的超高温（UHT）乳。在原料乳和UHT乳中发现了类似的脂质类别和脂肪酸组成的季节性变化。在商业加工过程中，UHT乳中的脂质含量被标准化至约1.5%。使用共聚焦激光扫描显微镜（CLSM）观察到，脂肪球直径减小（约1µm）且球膜变薄。脂质类别的分布发生了改变，三酰甘油比例降低，同时磷脂和游离脂肪酸增加。饱和脂肪酸C12:0和C14:0、反式脂肪酸（包括共轭亚油酸（CLA））、多不饱和脂肪酸C18:2(n-6)和C18:3(n-3)在UHT乳中的比例增加。这些结果表明了UHT加工对乳脂质特性的影响。
