Fermentation of the wort
Fermentation experiments were performed in 1nL glass batch
reactors system equipped with an agitator. After cleaning by steam
sterilization at 121°C for 15 min, the fermenter was filled with 750
ml of the fermentation medium with the addition of the following
nutrients (g/l): diammonium hydrogen phosphate, 0.5 g;
magnesium sulphate (MgSO4.7H2O), 0.2 g and urea, 0.5 g (Nigam
et al., 1998). One drop of antifoam was added to each reactor unit
to prevent foaming. Each reactor was inoculated with 1% (w/v) of
the yeast strains. The fermentation was allowed to proceed at room
temperature (25 ± 2°C) for five days. The agitation speed was
maintained through out the experiment at 200 rpm for even
distribution of the yeast and the nutrient respectively. The wine was
clarified with 0.1% bentonite, racked and stored at 2°C until
analyzed.