Effect of fermentation conditions on yeast growth and volatile composition of wine produced from mango (Mangifera indica L.) fruit juice

In this study mango juice fermentation at laboratory scale with controlled inoculation using selected yeast strain was performed (Saccharomyces cerevisiae 101). Effect of fermentation conditions (temperature, pH, SO2 and aeration) on wine fermentation was evaluated based on yeast growth, duration, fermentation rate and volatile composition. The composition of the major volatile compounds with low boiling points was determined by gas chromatography under the different operating conditions of fermentation temperature (15–35 °C), pH (3.5–6.0), SO2 (100–300 ppm) and aeration (initial dissolved O2 and shaking at 30 rpm). Temperature had important effect on yeast growth and on the levels of volatile compounds. It was observed that the final concentrations of ethyl acetate and some of the higher alcohols decreased when fermentation temperature increased to 25 °C (35 mg/l at 15 °C and 27 mg/l at 25 °C). SO2 stimulated the yeast growth up to certain level and in excess it inhibited the yeast metabolism. Ethanol concentration slightly increased with the addition of 100 ppm SO2 (8.2 g/l) and decreased with increase in concentration of SO2 (6.2 g/l in 300 ppm SO2). Aeration by shaking increased the viable cell count (from 52 × 106 in the absence of oxygen to 98 × 106 in shaking at 30 rpm) but decreased the ethanol productivity (from 7.2 in initial dissolved O2 to 6.5 g/l shaking at 30 rpm). With the results obtained it was concluded that the temperature (25 °C), pH (5), SO2 (100 ppm) and must with initial oxygen were optimum for better quality of wine from mango fruits. The results of the present study considering the traditionally recognized preference for low alcoholic fermentation temperatures in wine making.

Research highlights▶ Fermentation temperature has much influence on the wine quality and yeast growth. ▶ Increase in temperature increased the volatile composition and also yeast biomass up to certain level. ▶ It is also confirmed that the optimum pH is very important to produce good quality wines. ▶ SO2 addition attributes the wine quality. But high concentrations decrease the yeast growth. ▶ Optimum conditions for better quality mango wines are 25 °C temperature, pH 5, 100 ppm SO2 and juice with initial oxygen.