Fermentation Kinetics of Soursop Juice Using Saccharomyces Cerevisiae with Influence of Ammonium Carbonate
C Ogbebor
Soursop juice was fermented as substrate in the presence of ammonium carbonate using saccharomyces cerevisiae to determine kinetic parameters: overall rate constant; k, order of initial reaction; n, maximum rate of fermentation; V max, catalytic constant; k 2, dissociation constant for the enzyme -substrate complex; k s, the Michaelis constant; k m, and the specific ac tivity of th e enzyme. These were obtained by monitoring the rate of carbon (IV) oxide production at different time intervals. It was observed that in the first order reaction, the overall rate constant k, with respect to ammonium carbonate is, 2.23. It's also seen tha t the curves achieved from the plots of volume of carbon dioxide produced with time approached the time axis in a shorter time and the reaction was faster upon its addition. Most importantly, the maximum rate of fermentation with the substrate, 2.58x102M1min-1 and ad dition of ammonium carbonate is 2.49x102Mmin-1. The value represents the maximum velocity attainable. The maximum rate at which all the enzyme molecules were in the complex form was high and became lower upon the addition of the additive. This s uggests inhibition of the fermentation process by the additive due to decrease in the maximum activity of the enzyme. The catalytic constant, k 2, 8x10-2min-1 and the value upon addition of ammonium carbonate is, 2.0x10 -2 min-1 The dissociation constant of enzyme-substrate complexes, k s 1.64x102 and for the addition of ammonium carbonate is, 5.30x10 -1. The Michaelis constant, k m 1.64x102 M and 5.30x10 -1 for ammonium carbonate. The specific activity which is the unit of enzyme activity per gram of protein (yeast) is found to be 1x10 -1 in both. Finally, the effect was found to be uncompetitive from the extrapolated Lineweaver-Burk plots.