Q. What are the primary source of energy ?
Oils and fats form an integral part of the dietaries the world over. In the body they are the primary source of energy. As you know, chemically they are complex mixtures of esters of fatty acids and glycerol. Fat in the liquid state is known as oil. There are various types of fatty acids present, which may be saturated or unsaturated in nature. Hence, the composition of different fats/oils depends upon the types of fatty acids present namely, stearic, oleic, palmitic, recinolic etc. Table 4.1 gives you fatty acid composition of some edible fats and oils. Different forms of oils or fats are available namely, crude oil, refined oil, lard, hydrogenated fats, butter, ghee, margarine and shortenings. You will note that acidity in oils/fats is frequently expressed as the percentage of free fatty acids present in the sample. The percentage of free fatty acid in most of the oils and fats is calculated on the basis of oleic acid, although in coconut oil and palm kernel oil it is often calculated in terms of lauric acid, in castor oil in terms of ricinoleic acid and in palm oil in terms of palmitic acid. However, the overall composition of fatty acids in a given sample of oil/fat is conducted through GLC (Gas Liquid Chromatography technique).