Glucose syrup production from cocoyam (Colocasia escluenta) tubers using Aspergillus niger

Abstract

Glucose syrup is a highly valued liquid sweetener and a commercially important product. It is widely used by the beverage, confectionery, food and pharmaceutical industries. However, glucose syrup production by extraction of starch from cocoyam involves grating of raw material, settling, sieving, slurry decantation and finally drying the starch. Therefore, in order to simplify these processes, the present work aimed at one-pot glucose syrup production from cocoyam tuberby Aspergillus niger. The effects of various process parametres such as cell concentration, substrate concentration, pH and temperature were investigated. It was found from this study, that, an increase in substrate concentration was accompanied with a proportionate increase in glucose concentration up to 20.1g/L and decrease in glucose yield, falling from 88 to 49%. This could be as a result inhibition, generally lower substrate concentrations are more suitable in order to avoid it. In addition, an increase in cell concentration resulted to increase in both the concentration and yield of glucose.The application of Aspergillus niger was found to directly hydrolysed cocoyam tubers (without starch extraction) to glucose atbest operating temperature of 45^oC and pH of 4.5 within the range of time investigated.