Effect of Tween 80 and ergosterol supplementation on fermentation performance of the immobilized yeast in high gravity brewing

This paper deals with the effect of Tween 80 and ergosterol supplementation to the 24oPt wort with 30% maltose syrup adjunct on the fermentation performance of the immobilized yeast in calcium alginate gel. The higher the content of supplements in the wort, the higher the yeast growth, the sugar and free amino nitrogen consumption rates and the ethanol production rate but the lower the ethanol content in the green beer. The star distance of central composite circumscribed design was used to study the influence of Tween 80 and ergosterol on the ethanol concentration in the green beer. The optimal content of Tween 80 and ergosterol supplemented to the wort were 0.3%v/v and 18mg/L, respectively. In these conditions, the primary fermentation time reduced 22.2% and the ethanol concentration in the green beer was similar in comparision with those of the control sample.