A cryotolerant and alcohol tolerant strain of Saccharomyces cerevisiae was immobilized on gluten pellets and examined by electron microscopy. The biocatalyst was used for repeated batch fermentations in glucose and must for wine making at 30, 15, 10, 5 and 0 degrees, without any loss of activity. This biocatalyst produced at least a three-fold increase in the fermentation rate when compared with free cells and reduced the activation energy, E(a). Wine and ethanol productivities obtained at 15 degrees C were about half those obtained at 30 degrees C. At 10 degrees C the average wine productivity was about 30% of that obtained at 30 degrees C. For each temperature, ethanol and wine productivities for immobilized cells were higher than those for free cells and the improvement increased as the temperature was decreased At temperatures lower than 10 degrees C, wine productivities were four to seven times higher than those of the free cells.