The relationship between polypeptides and foaming during fermentation

The foam level during fermentations of hopped and unhopped wort and with fresh yeast and successive generations of yeast was examined. Simultaneously the total and hydrophobic polypeptide contents in worts, fermented worts and their concomitant foams were checked. It was shown that the total and hydrophobic polypeptide contents of the foam fraction and the foam level during fermentation were dependent on the generation number of yeast. The early generations of yeast (generations 1 and 2) promoted the formation of the largest amount of foam. It was also observed that a higher volume of foam occurred during fermentation of hopped wort in respect to unhopped one despite a higher concentration of polypeptides in unhopped wort. It could be a consequence of a higher foaming potential of polypeptides in hopped wort. The findings of the work may result in the limitation of foaming in the fermenters and consequently the increase of the brewery productivity without using additives and compromising the quality of the final product.