II) Disaccharides

II) Disaccharides

    Disaccharides are formed by the combination of two monosaccharides by the elimination of one molecule of water. The disaccharides of nutritional importance are
    i) Sucrose ii) Maltose iii) Lactose

    i)Sucrose (cane sugar/beet sugar)
    • Sugar cane and beet root, the sources of sucrose containing 10-12 % and 12-18% respectively are employed for large scale manufacturing.
    • Sucrose is hydrolysed to glucose and fructose by dilute mineral acids or by the enzyme sucrase present in intestinal juice.

    ii)Maltose (Malt sugar)
    • Maltose is present in malt.
    • It is formed in cereal grains (barley, jowar, ragi etc) during germination by the hydrolysis of starch by the enzyme diastase (Amylase) Amylase
    Starch ------->Maltose
    Maltose +H2O ------> glucose (2 molecules)

    iii)Lactose (Milk sugar)
    • Lactose occurs in the milk of all mammals but has not so far been found in plant foods. Lactose is hydrolysed to glucose and galactose by the enzyme lactase present in the intestinal juice.
    Lactose + H2O -----> glucosd + galactose

Last modified: Monday, 18 June 2012, 8:15 AM