BIOCHEMICAL CHARACTERISATION OF MAIZE FOR STARCH DIGESTIBLITY CHARACTERISTICS

Abstract

Maize, queen of cereals, is the most widely consumed cereal crop after wheat and rice. A maize kernel contains starch (75%) as the major component, which is composed of amylose (2530%) and amylopectin (7570%). Dietary starches vary greatly in digestibility. Resistant Starch (RS), a fraction that escapes the enzymatic hydrolysis, is positively correlated to amylose content which owing to lesser number of reducing ends, is more resistant to digestion, making RS more desirable for diabetics. This directs the present study, which aims at screening high amylose germplasm from eighty Quality Protein Maize lines which were analysed for starch, amylose and amylopectin content. The germplasm is broadly characterised into low (1621%), medium (2128%) and high amylose (more than 28%) lines. It was observed that 17 lines had low, 14 had high and rest had moderate amylose content. The screened high amylose lines were enzymatically analysed for RS, RDS and SDS content. The method deals with starch isolation using NaOH under cold conditions followed by addition of αamylase and amyloglucosidase for starch hydrolyses. Further the aliquot of hydrolysates taken at 20, 120 and 180 minutes were estimated for glucose content using GOPOD reagent at 510 nm. The present study screens high amylose nutritionally superior lines from the Indian germplasm, which can be further modified to amylose extender lines so as to serve a potential substitute for fibrous constitutes in diet with an additional protection from the onset of bowel diseases.