EFFECT OF ASPERGILLUS NIGER AMYLASES ON CASSAVA STARCH HYDROLYSIS

EFFECT OF ASPERGILLUS NIGER AMYLASES ON CASSAVA STARCH HYDROLYSIS

Abstract:

The enzymatic hydrolysis of cassava starch to glucose has been studied. Aspergillus niger was isolated from deteriorated groundnut seeds and used as the amylase producer source. The effect of various process variables such as culture age, mycelia mass loading, pH, temperature and substrate (cassava starch) concentration were investigated in order to optimize the hydrolysis process. The A. niger amylases exhibited optimum activity at pH and temperature of 4.8 and 60oC respectively. The cells appear most viable on the fifth day. Results obtained from this study indicated that increase in cassava starch concentration from 0.3 to 1.5 g/l was accompanied with a proportionate increase in glucose concentration from 0.239 to 0.310 g/l and decrease in glucose yield, falling from 74% to 18%. In addition, increase in mycelia mass loading resulted to increase in both the concentration and yield of glucose. An initial rate method was employed in estimating the kinetic parameters using Michealis-Menten model. The Langmuir form of the Michealis-Menten model gave a high regression coefficient (0.9939) and the values of the maximum reaction velocity (rmax) and Michaelis constant (Km) were found to be 2.42*10-3 g/l.min and 0.221 g/l respectively

EFFECT OF ASPERGILLUS NIGER AMYLASES ON CASSAVA STARCH HYDROLYSIS