Influence of Adjunct Carbohydrate Spectrum on the Fermentative Activity of a Brewing Strain of Saccharomyces cerevisiae. M. Phaweni, E. S. C. O'Connor-Cox, A. T. W. Pickerell, and B. C. Axcell, The South African Breweries Ltd., P.O. Box 782178, Sandton, 2146, South Africa. J. Am. Soc. Brew. Chem. 51:0010, 1993.

The growth and fermentative activity of a commercial Saccharomyces cerevisiae strain varied considerably when fermentations were conducted in worts formulated with different adjuncts. This strain was not susceptible to glucose repression of maltose and maltotriose uptake but was sensitive to changes in the wort glucose concentration. High concentrations of initial wort glucose increased the formation of sulfur dioxide and acetaldehyde. The yeast growth pattern and the fermentation rate were modified by the wort carbohydrate profile. The effects on these critical fermentation parameters were even greater when the physiological quality of the yeast was compromised. It is hypothesized that a complex operational system regulated by the metabolic state of the yeast and the strain-specific carbohydrate uptake pattern resulted in the effects. Syrup adjuncts containing high glucose concentrations inhibited the fermentative and growth properties of the yeast while contributing to the overproduction of flavor-active compounds.

Keywords: Acetaldehyde, Adjunct, Carbohydrate spectrum, Fermentative activity, Growth, Physiological condition, SO₂