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Use of isoâosmolality plots to characterize yeast fermentative performance
- Jones, R. P.
- Journal of applied microbiology 1987 v.62 no.4 pp. 349-359
- environmental factors, ethanol, fermentation, glucose, nutrition, osmolality, temperature, water activity, yeasts
- Yeast fermentation data (ethanol product, P, vs glucose substrate, S) can be plotted on a graph showing lines of equivalent osmolality or water activity. Comparison of such plots for different strains and for single strains under different environmental conditions shows the conditions for optimum performance. With these plots the product/substrate yield coefficient (Yp/s) can be shown to vary with time, contrary to its usually assumed constant value. Under conditions of optimum environment and nutrition, five of the yeast strains tested ceased growing at a characteristic value of solution osmolality, indicating that the inhibitory effects of ethanol and glucose, to a first approximation, are the result of their molar contribution to water activity rather than due to any specific cellular effect. In one yeast strain this characteristic behaviour was not affected by temperature variations between 30Â° and 36Â°C.