Using high pitching rate for improvement of yeast fermentation performance in high gravity brewing

One of the promising methods to improve yeast fermentation performance in high gravity brewing is to increase pitching rate in the bioreactor. In this study, fermentation with four different pitching rates (1.5×107, 4.5×107, 7.5×107, and 10.5×107 viable cells/ml wort) was carried out to investigate the impact of pitching rate on yeast fermentation performance and beer quality from 24oBx wort. The obtained results showed that higher pitching rate resulted in higher maximum yeast cell number in the culture, higher sugar uptake and ethanol production rates, but higher diacetyl level in the green beer as well. The results also indicated that this method itself was even more efficient than a method of supplementing nutrients (Tween 80 and yeast extract) to wort, or a combination of these two methods in respect of the sugar uptake, ethanol production rates; ethanol, and diacetyl concentrations in the green beer.