The trans fatty acid and positional (sn-2) fatty acid composition of some Australian margarines, dairy blends and animal fats.

We have analysed the fatty acid (FA) composition including the trans fatty acid by GLC and Fourier Transform Infra-Red (FTIR) Spectrophotometry of 13 margarines, five butter/dairy blends and two animal fats (lard and dripping). The samples were purchased from supermarkets in three separate locations across Victoria: Gladstone Park (near Melbourne), Waurn Ponds (near Geelong) and Geelong city. From the FA composition, the P/S, P/(S+trans monoenoic FA), P/M(S+trans monoenoic FA) and w6/w3 ratios were calculated. The FA composition and trans FA content were compared with the last published analysis of Australian margarines in Sydney in 1982. The FA composition of the sn-2 position was obtained by pancreatic lipase deacylation of the whole triglycerides (TG) . From this data, we estimated the per cent interesterified fat which was present in the margarines. The trans FA content of the margarines which was determined by FTIR ranged from 9.2% to 16.3% (mean of 13.1% of total FAME) (7.6 g-13.0 g trans FA/100 g sample, mean of 10.4 g/100 g sample) and from 3.2% to 4.1% (mean of 3.8%) for butter and dairy blends. Lard contained 0.4% trans FA while dripping consisted of 3.6% trans FA. The trans FA content in the margarines was similar to the values published in 1982 with the exception of four brands. The w6/w3 ranged from 2.5 to 363 and the P/S ranged from 1.4 to 3.3 compared with the 1982 figures where the w6/w3 ranged from 3 to 49 and the P/S ranged from 0.1 to 3.7. The estimated per cent interesterified fat in the margarines ranged from 25% to 100%. We estimated the total trans FA intake in the Australian diet to be between 2.7 g/head/day and 4.8 g/head/day. We also estimated that table margarines account for between 36% and 64% of the total trans FA intake in the Australian diet.