Impact of processing on formation of trans fatty acids

Trans fatty acids are formed during hydrogenation which is done to improve the functionality and oxidative stability of oils. Several process conditions affect the content of trans fatty acids in hydrogenated oil. There is conflicting evidence as to whether intake of trans fatty acids, in foods such as margarine, affects the types and levels of cholesterol produced in the blood. Epidemiological studies have shown associated increases in total cholesterol and low density lipoproteins, as well as decreased levels of high density lipo-proteins in the blood. It is unknown whether these effects are related directly to trans fatty acids or to the decrease of unsaturated fatty acids in the diet. This chapter will cover the recent nutritional status of trans fatty acids and the effect of processing on the levels of trans fatty acids in foods.