COMPARISON OF THE FATTY-ACIDS AND THE ISO MERIC DISTRIBUTION OF TRANS-C18 1 FATTY-ACIDS OF MILK-FAT, MARGARINE, SHORTENINGS, COOKING AND DIETETIC FATS/

Especially in recent years, trans fatty acids have been correlated wit h health risks such as atherosclerosis and cardiovascular diseases. Fo r that reason, 1756 milk fats and 123 German edible fats of vegetable origin were analyzed gas chromatographically for the contents of all m ajor fatty acids as well as 10 positional isomers of trans-C18:1 and c ompared. Using optimized GC conditions, even a separation of trans Del ta 13 and Delta 14 as well as of nearly baseline resolved peaks of the individual isomers was achieved for the first time. On the basis of a nalyses of different batches of the same brands, the average content o f trans-C18:1 in partially hydrogenated margarines was found to have d ecreased from August 1994 till December 1994 and January 1996 by 22 % and 52 %, respectively, while trans contents in partially hydrogenated cooking fats and shortenings remained on a high level. According to c urrent analyses milk fats, margarines and cooking fats/shortenings) sh ow, on average, trans-C18:1 contents of 3.6 %, 4.6 % and 11.9 %, respe ctively. Moreover, the examinations exhibited that elaidic acid (C18:1 -trans Delta 9), that is frequently used in clinical studies, only occ urs in relatively small amounts of 0.23 %, on average, in bovine milk fat. Compared with that, partially hydrogenated margarines with 2.04 % (1994) and ca. 1 % (1996) and partially hydrogenated cooking fats/sho rtenings with 2.28 %, on average, contain considerably higher concentr ations. On the other hand, with 1.72 % vaccenic acid (trans Delta 11) is the main isomer in milk fat, whereas with 1.38 % (1994) and 0.7 % ( 1996) margarines and with 1.45 % cooking fats contain smaller amounts. These differences could be important for the discussion on the differ ent atherogenic potential of animal and vegetable fats. Finally, the o btained data were used to discuss the daily intake of the different po sitional isomers of trans-C18:1 from bovine milk fat, margarine and co oking fats/shortenings.