Studies of Saccharomyces cerevisiae during fermentation--an in vivo electrokinetic investigation.

An extensive in vivo study of the electrokinetic properties of six strains of the brewing yeast S. cerevisiae has been carried out. The yeasts were cultured under laboratory conditions. They were electrokinetically characterized by the electro-osmotic dipped cell technique, and data are presented as zeta-potentials. The effects of pH, fermentation time, successive fermentation cycles, and initial wort density have been established. The electrokinetic properties of an ale yeast which did not function correctly during commercial fermentation have also been examined. The results are discussed in the context of two controversial topics concerning the mechanism of yeast flocculation, the relative importance of yeast cell wall carboxyl and phosphate groups and the influence of wort components.