Abstract
In our previous paper, we reported that the fermentation products play an important role on the injury of yeast cells in frozen dough. The purpose of present paper was to investigate the effect of ethanol and wheat flour on the injury of yeast cells during frozen storage at -20°C for 7 days.
Yeast cells of dormant state were not affected by the presence of ethanol up to 20%(v/v). The yeast cells fermented for 3 hours prior to freezing (3hr-cells) were considerably injured when frozen in distilled water, for storage. However, the frozen yeast cells were protected by the presence ofethanol, and considerable protective effect was seen in between 5-20% when frozen. Methanol, at 20% concentration, showed superior protective effect to ethanol for 3hr-cells. On the other hand, alcohols with more than three carbon atoms were considerably detrimental, and fermentation activity of the yeast cells were completley lost after frozen storage. Wheat flour showed protective effect, whereas the coexistence of wheat flour and ethanol was harmful, and the injury of yeast cells increased during frozen storage.
