Optimization of cassava starch hydrolysis to fermentable sugars using sorghum malt

Abstract

This study aimed to optimize the hydrolysis of cassava starch to fermentable sugars using traditionally manufactured sorghum malt in Uganda. Two batches of sorghum malts were used; Malt 1 (malt from red sorghum) and Malt 2 (malt from white sorghum), both were purchased from the local markets of Kasubi and Kikoni respectively in the surbarbs of Kampala City. The Diastatic activities of both malts were determined using a method adapted from Diaber and modified to a micro-method in order to reduce the sample size to 0.5g malt. The diastatic power of Malt 1 and Malt 2 ranged from 70.00 to 70.73 DU/g and 63.82 to 67.09 DU/g respectively. This indicates that red sorghum grain produces malts with higher amylase activities than the white malt. About 20.0g of each cassava flour (Flour 1 and Flour 2) also purchased from local markets, Kasubi and Kikoni respectively, were each hydrolyzed with Malt 1 and Malt 2 differently, at series of malt concentrations and the resultant reducing sugar concentration determined using quantitative Benedict’s assay. The cassava flour was hydrolyzed with Malt 1 and Malt 2 and the yields of fermentable sugars from each ranged from 2.44 to 8.78% and 2.21 to 7.87% respectively. This indicated that Malt 1 has a higher hydrolytic activity than Malt 2.