The Effect of Nescafe Brand of Coffee on the Fermentative Activity of Baker\'s Yeast (<i>Saccharomyces cerevisiae</i>) On Sucrose

Abstract

The effects of increasing concentrations of Nescafe brand of coffee on the fermentative activity of baker\'s yeast (Saccharomyces cerevisiae) on sucrose were investigated. Phytochemical analysis showed the presence of alkaloids, tannins, saponins and flavonoids in samples containing nescafe coffee. Using increasing nescafe coffee concentrations of 0.6g, 1.2g and 1.8g, respectively, per 500ml sample solution each, decreased the average pH value of the must from 5.12 for the control sample, to 4.76, 4.68 and 4.54, respectively, for the test samples. The average ethanol contents (% v/v) were increased significantly (P<0.05) from 1.58 for the control sample to 3.48, 4.20 and 5.08, respectively, for the test samples after six (6) weeks of fermentation. The maximum velocity (V_max) increased, though not significantly (P≤0.05), from 9.01 x 10 ^-12μM/min for the control sample to 1.79 x 10^-11μM/min, 2.63 x 10^-11 μM/min and 3.57 x10^-11 μM/min, respectively, for the test samples indicating activation; with significantly (P≤0.05) increasing activation coefficient (Ea) values of 0.98, 1.92 and 2.96, respectively, for the test samples. Increasing concentrations of Nescafe coffee did not however change the Michaelis constant (k_m) value of 2.25 x 10<sup>-3mM. The results indicated that the nescafe coffee activated the baker\'s yeast fermentative activity on sucrose.

KEY WORDS: Activation, Nescafe Coffee, Enzyme, Fermentation, Yeast.

Global Journal of Pure and Applied Sciences Vol.11(2) 2005: 217-219</sup>