Liquefaction and Saccharification of High and Low Amylose Corn for Ethanol Production

Maize is known as the 'Queen of Cereals' and ranks second in terms of global acreage. It is one of the most significant renewable natural carbohydrate raw materials for the production of bioethanol. The proximate analysis of eleven corn genotypes showed significant variation in starch, crude protein, crude fat, crude fiber and ash content. The studies on amylose and amylopectin components of starch showed that the corn genotype PMH 7 was found to possess significantly high amylose content of 33.80 g100 gm^-1 while the corn genotype PML1012 was found to possess very low amylose content of 3.73 g100 gm^-1. Liquefaction of high and low amylose corn starch of genotypes PMH7 and PML1012 with alpha amylase at 6.0 KNU g^-1 resulted in maximum reducing sugars content of 48.31 and 50.30 mg g^-1, respectively in the mash. Further, saccharification of the liquified mash with glucoamylase at an enzyme dosage of 7 AGU g^-1 produced maximum reducing sugars of 549.92 and 577.89 mg g^-1 with conversion efficiencies of 77.02 and 83.07 per cent, respectively. The ethanol concentration of 8.30% (v/v) was reported to be maximum in the fermented mash of low amylose corn genotype PML1012 as compared to corn genotype PMH7. The high ethanol concentration obtained in the fermented mash of inbred line PML1012 suggested the potential utilization of this low amylose corn for bulk industrial ethanol production.