Abstract
1. Ricard's work showed that yeast spores of the Saccharomyces-type appear to be resistant forms that can withstand a high concentration of SO2 for considerable length of tlme without destroying ability to germinate. This aroused some curiosity as to the ability of vegetative yeast cells to withstand SO2. Yeast cells freshly removed from growing cultures were sensitive to relatively low concentrations of SO2.
2. The wine spoilage type yeasts tested proved to be much less resistant to SO2 than was the Saccharomyces-type. This is of interest because the spoilage type yeasts are primarily oxidative in metabolism, while the Saccharomyces-type used is both oxidative and strongly fermentative.
3. The pH range found in California wines has no appreciable effect in varying the action of SO2 on the Saccharomyces-type yeast.
4. It was found that the Saccharomyces-type cells absorbed measurable amounts of SO2, some of which was given up when the exposed cells were placed in SO2 free water. Cells made apparently nonviable by the SO2 treatment up to 2 hours'exposure were not revived by washing with water. The effect of sufficient amounts of SO2 is nonreversibly inhibitory after 2 hours.
5. The data indicate that water solutions containing relatively small concentrations of SO2 are useful in winery sanitation such as cleaning equipment. Large numbers of yeast spores, however, may survive the application of SO2. The concentration of SO2 which will prevent yeast spore germination is not known.
6. The idea that relatively small concentrations of SO2 in must are effective in destroying the activity of oxidative spoilage yeasts is supported by this data.
- Copyright 1951 by the American Society of Enology
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