Temperature Coefficient of Alcoholic Fermentation by Yeast.
The temperature coefficient of fermentation by living yeast has been carefully determined by Slator by measurements of the initial rates at a series of temperatures from 5° to 40° C. The coefficient is found to be of the same order as that for many chemical reactions, but to vary considerably with the temperature, a rise in temperature corresponding with a diminution in the coefficient. The following values were obtained for glucose; they are independent of the concentration of yeast and glucose, the class of yeast, and presence or absence of nutrient salts, and remain the same when inhibiting agents are present. Almost precisely the same ratios are obtained for fructose and mannose:—
| t. | V(t+5)/Vt. | V(t+10)/Vt. |
|---|---|---|
| 5 | 2·65 | 5·6 |
| 10 | 2·11 | 3·8 |
| 15 | 1·80 | 2·8 |
| 20 | 1·57 | 2·25 |
| 25 | 1·43 | 1·95 |
| 30 | 1·35 | 1·6 |
| 35 | 1·20 |
Aberson's result, K(t+10)/Kt = 2·72, which represents the mean coefficient for 10° between 12° and 33°, agrees well with this. [p130]