Particle nature, yeast strain, and temperature interactions on the fermentation rates of grape juice.

Yeast strains of Saccharomyces cerevisiae behave differently to additions of finely sized particles added to clear grape juice. The type of material has a bearing on the effectiveness of increasing the rate of sugar conversion. In comparsion with a control sample, stirring and then adding grape solids back to the juice are most effective in maximizing sugar conversion, followed by addition of bentonite, talc, and diatomaceous earth. The improved fermentation efficiency is greater for all additions compared with unstirred controls. The formation of yeast flocs is enhanced by all additions. This fact can be used to partially explain the more effective fermentation rates. These additions appear to be equally effective over temperatures covering the normal fermentation temperature range.