TRANS-OCTADECENOIC ACIDS IN MILK-FAT AND MARGARINE

Trans fatty acids are reported to have a distinct influence on the LDL- and HDL-cholesterol level as well as on the Lp(a)-lipoprotein level. Based on the gas chromatographic analysis of fatty acids by a very polar capillary column of 100 m and of triglycerides from numerous milk fats a triglyceride formula was developed, that was used for the determination of the content of trans C18:1 fatty acids in 1736 different milk fats and its dependence on feeding conditions. These milk fats, covering a wide scope of feeding and lactation conditions, exhibit a scattering range of 1.20 to 6.55 wt% with a mean value of 3.38 wt% for the trans-octadecenoic acids and of 1.06 to 1.64 wt% with a mean value of 1.38 wt% for the cis-octadecenoic acids (without oleic acid). These results can be used for a new estimation of the uptake of trans fatty acids by milk products in Germany, leading to an amount of 1.20 g per day and person. Further measurements of different margarine samples partly led to contents of trans-octadecenic acids being 8 times higher than in milk fats. Whereas maximum values of 25 wt% of the whole fatty acids were found in these margarines, there are also edible fats with low trans fatty acidlevels on the market.