Fat is a source of energy and a part of the cell membrane construction. Animal fat and vegetable oils consist of the most common lipid; triacylglycerol. Triacylglycerol consists of glycerol and three fatty acids joined by ester linkages. The fatty acids are divided into three groups; saturated, monounsaturated and polyunsaturated. The fatty acids affect the characteristics of the fat. A high portion saturated fatty acids results in a fat with a relatively high melting point, like butter or margarine. If a fat contains a high portion unsaturated fatty acids, like vegetable oils, the melting point is relatively low. The unsaturated fatty acids are more reactive than the saturated fatty acids. The configuration of the double bond also affects the characteristics of the fat. Most common is the cis configuration.

Many investigations have shown that trans fatty acids are positively related to an increased risk for coronary heart disease while polyunsaturated fatty acids are negatively related. One study that we have read shows that saturated fatty acids increase the LDL-cholesterol level and there by increase the risk for coronary heart disease.

We have come to the conclusion that in most cases the fatty acid composition in food is analyzed by gas chromatography with flame ionization detector. There are three analyze steps that are important; preparation, separation and detection of the sample. The preparation step includes extraction of lipids and the preparation of methyl esters. In the separation step a chromatographic method is often used and gas chromatography is the most common. The detection step varies among the different kinds of fatty acids, but the flame ionization detector is the most commonly used.