Chemically Modified Starch

Starch is a homopolymer of glucose found naturally in abundance, having unique physicochemical properties, is biodegradable, low cost, can be obtained from many sources, and is widely accepted in the pharmaceutical and food industries. Native starches are unsuitable for most applications due to the presence of many hydroxyl groups and glycosidic bonds; these bonds, when subjected to hydrolysis in many treatments, result in loss of viscosity and thickening power, leading to retrogradation and other problems related to solubility. The presence of certain groups of primary importance like the carboxylic, ester, ether, and amino groups can improve hydrophobicity and related functional properties of starches. Chemical modifications of starch have the advantage of introducing new hydrophobic groups via esterification and etherification, and creating strong bonds within molecules via crosslinking, condensing reaction, etc.; thus, the shortcomings of native starches related to its functional properties can be eliminated. In recent years, various procedures have been formulated by to extract the starch with chemical means. Thus, to provide a complete overlay of chemical modification (hydrolysis, cross-linking, esterification, etherification, oxidation, and grafting, etc.,) of starch, the chapter has been designed which also provides a complete overview of improved functional properties of starches after modification.