Ferreiro T, Gayoso L, Rodríguez-Otero J L
Instituto de Investigación y Análisis de Alimentos, Universidad de Santiago de Compostela, Facultad de Veterinaria, 27002 Lugo, Spain.
Instituto de Investigación y Análisis de Alimentos, Universidad de Santiago de Compostela, Facultad de Veterinaria, 27002 Lugo, Spain.
J Dairy Sci. 2015 Jan;98(1):9-14. doi: 10.3168/jds.2014-8244. Epub 2014 Nov 14.
The objective of this study was to compare the phospholipid content of conventional milk with that of organic milk and milk rich in conjugated linoleic acid (CLA). The membrane enclosing the fat globules of milk is composed, in part, of phospholipids, which have properties of interest for the development of so-called functional foods and technologically novel ingredients. They include phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylserine (PS), and the sphingophospholipid sphingomyelin (SM). Milk from organically managed cows contains higher levels of vitamins, antioxidants, and unsaturated fatty acids than conventionally produced milk, but we know of no study with analogous comparisons of major phospholipid contents. In addition, the use of polyunsaturated-lipid-rich feed supplement (extruded linseed) has been reported to increase the phospholipid content of milk. Because supplementation with linseed and increased unsaturated fatty acid content are the main dietary modifications used for production of CLA-rich milk, we investigated whether these modifications would lead to this milk having higher phospholipid content. We used HPLC with evaporative light scattering detection to determine PE, PI, PC, PS, and SM contents in 16 samples of organic milk and 8 samples of CLA-rich milk, in each case together with matching reference samples of conventionally produced milk taken on the same days and in the same geographical areas as the organic and CLA-rich samples. Compared with conventional milk and milk fat, organic milk and milk fat had significantly higher levels of all the phospholipids studied. This is attributable to the differences between the 2 systems of milk production, among which the most influential are probably differences in diet and physical exercise. The CLA-rich milk fat had significantly higher levels of PI, PS, and PC than conventional milk fat, which is also attributed to dietary differences: rations for CLA-rich milk production included linseed supplement and contained less maize meal than conventional rations and a greater proportion of unsaturated fatty acids and salts. The relative proportions of the phospholipids studied were similar in all 3 types of milk, descending in the order PE>(PC, SM)>PS>PI, with PC being slightly more abundant than SM in organic milk and vice versa in CLA-rich milk.
本研究的目的是比较传统牛奶与有机牛奶以及富含共轭亚油酸（CLA）的牛奶的磷脂含量。包裹牛奶脂肪球的膜部分由磷脂组成，磷脂对于所谓功能性食品和技术新颖成分的开发具有重要特性。它们包括磷脂酰乙醇胺（PE）、磷脂酰肌醇（PI）、磷脂酰胆碱（PC）、磷脂酰丝氨酸（PS）以及鞘磷脂（SM）。有机管理奶牛产的牛奶比传统生产的牛奶含有更高水平的维生素、抗氧化剂和不饱和脂肪酸，但我们尚未发现有研究对主要磷脂含量进行类似比较。此外，据报道使用富含多不饱和脂质的饲料补充剂（挤压亚麻籽）可增加牛奶中的磷脂含量。由于补充亚麻籽和增加不饱和脂肪酸含量是生产富含CLA牛奶所采用的主要饮食调整方式，我们研究了这些调整是否会使这种牛奶具有更高的磷脂含量。我们使用带蒸发光散射检测的高效液相色谱法测定了16份有机牛奶样品和8份富含CLA牛奶样品中的PE、PI、PC、PS和SM含量，每种情况下都与同一天、同一地理区域采集的与有机和富含CLA样品相匹配的传统生产牛奶的参考样品一起测定。与传统牛奶和乳脂肪相比，有机牛奶和乳脂肪中所研究的所有磷脂含量均显著更高。这归因于两种牛奶生产系统之间的差异，其中最具影响力的可能是饮食和体育锻炼方面的差异。富含CLA的乳脂肪中PI、PS和PC的含量显著高于传统乳脂肪，这同样归因于饮食差异：生产富含CLA牛奶的日粮中包含亚麻籽补充剂，且玉米粉含量低于传统日粮，不饱和脂肪酸和盐分的比例更高。所研究的磷脂的相对比例在所有三种类型的牛奶中相似，顺序为PE>(PC, SM)>PS>PI，在有机牛奶中PC比SM略多，而在富含CLA的牛奶中则相反。
