Lipids and its classification


    • The term ‘lipid’ is applied to a group of naturally occurring substances characterized by their insolubility in water, greasy feel and solubility in some organic solvents. They occur in the plant and animal kingdom.

    Oils and fats:
    These are esters of fatty acids and glycerol. Oils are liquid at 200C while fats are solid .

    Compound lipids
    They contain other organic compounds in addition to fatty acids and glycerol.

    Phospholipids (phosphotides)
    These contain phosphoric acid and nitrogeneous base in addition to fatty acids and glycerol e.g. (lecithin and cephalin)

    Compound lipids containing carbohydrates in combination with fatty acids and glycerol. e.g: cerebrosides

    These are esters of fatty acids and large chain aliphatic alcohols.

    Derived Lipids
    Substances derived from fat on hydrolysis or by enzyme activities are called derived lipids. Eg. fatty acids, alcohol

    Fatty acids
    Fatty acids in foods and in the body contain 4-24 carbon fatty acids

    Short chain fatty acids- 4-6 carbon atoms
    Medium chain fatty acids -8-12 carbon atoms
    Long chain fatty acids- more than 12 carbon atoms

    Fatty acids are divided into saturated fatty acid and unsaturated fatty acid

    Saturated fatty acids
    Saturated fatty acids have all the carbon atoms in the chain saturated with hydrogen atoms. eg. Palmitic, stearic, butyric acids

    Unsaturated fatty acids
    When a double bond is present between two carbon atoms the fatty acid is termed as unsaturated fatty acids. eg. Oleic acid

    Poly unsaturated fatty acids
    Three or more double bonds in a fat is called poly unsaturated fatty acids
    eg. Linoleic, linolenic and arachidonic acid

    Essential Fatty Acids
    Nutritionally important fatty acids are known as essential fatty acids. Since the body cannot synthesize them the EFA must be supplied to the body.

Last modified: Thursday, 21 June 2012, 9:10 AM