fatty acid In animals, many of the dietary lipids are hydrolyzed to free fatty acids (FFAs) before being absorbed and utilized further for lipid synthesis. Lipids can be hydrolyzed to FFAs in tissues by lipolytic enzymes, such as hormonesensitive lipase, lipoprotein lipase, and phospholipases A and C, before they are metabolised in many different pathways, including oxidation, desaturation, elongation and re-esterification. Fatty acid methyl esters (FAMEs) are a type of fatty acid ester that is derived by transesterification of fats with methanol. These molecules in biodiesel are mainly FAMEs, usually obtained from vegetable oils by transesterification. They are used to produce detergents and biodiesel. FAMES are usually produced by an alkali- catalyzed reaction between methanol and fats in the presence of base such as sodium methoxide or sodium hydroxide.