Fatty acids (FAs) are the major component of lipids, and the physical, chemical, and physiological properties of a lipid class depend primarily on its fatty acid composition. The composition of fatty acid is determined as the methyl esters of fatty acids by GC. Trans-fatty acids are a type of unsaturated fats that take place in small amounts in nature but became broadly produced industrially from vegetable fats for use in margarine, packaged baked goods, snack food and frying fast food starting in the 1950s.