Ethanol production varied with pH change of mango juice.
Based on the earlier studies, it was evident that 101 strain
produced maximum ethanol at pH 4.5–5. The pH of all varieties
of mango musts was around this range. Hence the pH
of mango must was not adjusted. The lowest concentration
(5% w/v) of ethanol was produced at pH 3.0 and highest (7.8%
w/v) was at pH 5.0 (Fig. 2). The ethanol concentration was
significantly (p < 0.005) increased with pH up to 5 and the
ethanol was greatly improved from pH 3 (5% w/v) to pH 5
(7.8%) (p < 0.05). Glycolytic enzymes are more active at near
neutral pH. The decrease in pH of grape must in course of
fermentation caused decrease in yeast internal pH and inhibition
of enzymes (Dombek and Ingram, 1987). This might be
the probable cause for low ethanol yields at low pH