Rancidity is the term used to represent the deterioration of fats and oils, resulting in an unpleasant taste. Fats containing unsaturated fatty acids are more susceptible to rancidity. The chemical changes which occur during rancidification are known as rancidity, and this takes place in two stages and are accordingly referred as the following:

Physical Properties They are insoluble in water but are readily soluble in fat solvents like alcohol, ether, chloroform, and so on. They are greasy to touch and leave an oily impression on paper. Pure glycerides are tasteless, odourless, and colourless. Fats used in food have specific flavour and colour. The flavour is attributed to the…

Triglycerides or neutral lipids are composed of three molecules of fatty acid, esterified to glycerol. The fatty acids may be of the same type; the resulting glyceride is called simple glycerides. If the three fatty acids in a given glyceride are different, then the resulting glyceride is called a mixed glyceride. The structure of triglycerides…

Simple lipids are those which contain esters of fatty acids and alcohol. They are further classified into fats and waxes. The alcohol in fats is glycerol, and the alcohol in waxes is anything other than glycerol. This alcohol has a higher molecular weight. Neutral lipid, fat, triacylglycerol, or triglycerides are esters of glycerol with fatty…

The classification proposed by Bloor is the most accepted classification for lipids. Lipid classification is elaborated in Figure 4.1.

Animal sources: Milk, egg, meat, liver, and fish oils. Plant sources: Nuts, seeds, and oils.

Fats are widely distributed in plants and animals tissues, from which, they can be extracted by fat solvents like alcohol and ether. In plants, they are particularly present in nuts, seeds, and certain leaves. In animals, cholesterol, phospholipids, and glycolipids are abundantly present in the nervous system. Fat is also deposited in subcutaneous tissues, mesenteric…

Lipids may be regarded as organic substances relatively insoluble in water, soluble in organic solvents (alcohol, ether, chloroform, and so on) actually or potentially related to fatty acids, and utilized by the living cells.