PHYSICAL PROPERTIES OF COMMERCIAL BREWING YEAST SUSPENSIONS

Abstract

The cell surface charge and microstructure of four commercial strains of brewing yeast were examined using electrokinetic and scanning electron microscopic (SEM) techniques. Flocculent and non‐flocculent ale and larger strains were observed to possess non‐normally distributed surface charges while suspended in buffers of various pH values with and without 1.0 mM calcium, 5% ethanol and 0.5 M KCl. Non‐normal charge distributions were also observed when the strains were suspended in commercial ale and lager beers. During SEM examination, a number of distinct structures appeared to be involved in cell‐to‐cell interactions. Observed differences in cell wall microstructure and the finding of non‐normally distributed surface charges indicate that these pure brewing strains possessed substantial phenotypical variation. 1993 The Institute of Brewing & Distilling