Carbohydrates are organic substances of polyhydroxy aldehyde or ketone derivatives. They are classified into monosaccharide, disaccharides, oligosaccharides and polysaccharides. Polysaccharides are of homo and heteropolysaccharides. Carbohydrates form stereoisomers like D and L-sugars are referred to as enantiomers (mirror images of each other). Carbon 1 of sugars is anomeric carbon atom (a-D glucose and b-D-glucose). The isomers formed due to variations in the configuration of –H and –OH around a single carbon atom in a sugar molecule is called as epimers (mannose and galactose are 2 and 4 epimers of glucose respectively). Sucrose is non-reducing and also called invert sugar.