Fatty Acid Profiles Needed for Dairy Foods from the United States

¹ Department of Nutritional Sciences, University of Connecticut, 186 Chaffeeville Road, Storrs, CT 06268-2673

It is now possible to resolve about 70 peaks of fatty acid methyl esters in bovine milk fats by gas-liquid chromatographic (GLC) analysis using capillary columns, 25 m or longer, coated with high resolution materials. Results using these methods have been reported by Precht and Molkentin (5) who employed a 25-m CP-Wax 58 capillary column. Comprehensive data on the fatty acids in French butters using similar but more detailed methods, have been reported by Wolff et al. (6). Similar profiles of the fatty acids in US dairy foods are not available (2) except for two analyses in reference (3), and one of these was from a Canadian butter. These data, shown in Table XV [in (3)], were analyzed at the request of the author. Palmquist et al. (4) provided data on the fatty acids in milk samples gathered from 50 cheese plants in 10 regions (19 states) in the US. However, the analyses were done with short packed columns, which can resolve only about 25 fatty acids.

It is important that we know the fatty acid profiles of dairy foods in the US. An example of the necessity is the reduction in fat content of milk associated with increased amounts of trans-octadecenoates in milk (1). Incidentally, most of the positional isomers can be identified if the fatty acid esters are first resolved into classes of unsaturates with argentation thin-layer chromatography (6). The data are needed. The study by Palmquist et al. (4) should be repeated using long polar capillary columns. We cannot make reliable recommendations about the health aspects of milk fat unless we know the kinds and amounts of fatty acids therein. I urge my colleagues to employ the best methods available for analyses of milk fatty acids and to report all of their results. Some investigators have done the former but not the latter. Comprehensive data are not available for dairy foods in the US.