Isolation and utilization of indigenous yeast strain for brewing of millet beer (OYOKPO)

Abstract

Three yeast strains were isolated from a spontaneously fermented native millet (Pennisetum typhoideum) malt beer (Oyokpo). One of the yeast isolates found to have the most highly fermenting capacity was characterised and identified as a strain of Saccharomyces cerevisiae. The yeast was then utilised as the pitching yeast in a subsequent controlled fermentation of millet wort at 20°C for 120 hours. Bitter leaf (Vernonia amagdalina) extract was used as the bittering and flavouring agent. The Oyokpo beer sample produced under these conditions was found to possess both chemical and organoleptic qualities comparable to some extent, to the conventional barley malt beer. At the end of fermentation, the pH, specific gravity, alcohol content, reducing sugar content and protein content of the beer were 4.11, 1.0308, 2.81% (v/v), 4.00 (mg/ml) and 0.84 (mg/ml) respectively.