Effect of Rehydration on Dry Wine Yeast Activity

Abstract

The effects of rehydration media and temperature on resulting fermentation activity were studied for nine commercial and experimental active dry wine yeasts. Water and grape juice were used as rehydration media at temperatures from 20 to 45°C. Fermentation activity was measured by gas production from grape juice according to a previously published method. The loss of cell constituents on rehydration was also measured and related to the physical form of the samples.

The optimal rehydration temperature was found to be about 38 to 40°C for all samples in either grape juice or water. The results indicate that although all the active dry wine yeasts may be added directly to must at cellar temperatures, fermentation activity is improved by the specified prior rehydration. The greater loss of cell constituents on low temperature rehydration was suggested as an explanation of the observed activity effects.