Analysis of trans fatty acid content in deep fried foods, milk and dairy products by attenuated total reflection-fourier transform infrared spectroscopy

The unsaturated fatty acid which has the double bond in the trans configuration is called trans fatty acid (TFA). TFAs are mostly found in partially hydrogenated vegetable oil which are commonly used in food process, especially in deep fried foods. It is because of high stability during deep-frying. Moreover, naturally occurring TFAs are found in milk and lipid tissues of ruminant. Several researchers showed that high consumption of diet high in TFAs was associated with greater risk of cardiovascular disease. Therefore, this study was conducted to investigate the TFA content in fifteen samples of deep fried foods and eighteen samples of milk and dairy products which were available in Bangkok area between February 2009 and September 2009, using attenuated total reflection fourier transform infrared spectroscopy. The total TFA content in this study expressed as grams of TFA content per 100 grams of food sample in eleven groups of foods were as follows: fried chicken from well-known fast food 0.08 – 0.14, fried chicken from street vender 0.01 – 0.02, french fries 0.05 – 0.10, deep fried dough stick (pa-tong-koh) 0.01 - 0.15, deep fried banana (kluay-kag) ND – 0.02, pasteurized milk 0.13 – 0.24, UHT milk 0.09 – 0.25, ice-cream 0.04 – 1.00, whipping cream 1.54 – 2.26, cheese 1.38 – 2.14 and butter 2.06 – 6.99. The mean TFA values in all selected foods ranged from 0.01 – 6.99 g/100 g food. From the present study, deep fried food category exhibited low TFA content. However, consumers should avoid and limit consuming this food because it contains high fat and may have some harmful compounds, which occur during frying. In milk and dairy products, the highest content of TFA was found in the selected brand of butter (6.99 g/100 g food).