Influence of Concentration of Dextrose on the Rate of Fermentation.
With regard to this important factor it is found that the action of living yeast follows the same law as that of most enzymes (p. [121]); within certain wide limits the rate of fermentation is almost independent of the concentration of the sugar. This conclusion has been drawn by many previous investigators from their experiments [Dumas, [1874]; Tammann, [1889]; Adrian Brown, [1892]; O'Sullivan, [1898], [1899]] and is implicitly contained in the results of Aberson [[1903]], although he himself regarded the reaction as monomolecular.
Fig. 8.
Slator, working with a suspension of ten to twelve yeast-cells per 1/4000 cubic millimetre at 30°, obtained the results which are embodied in the curve (Fig. 8).
This shows that, for the amount of yeast in question, the rate of fermentation is almost constant for concentrations of glucose between [p129] 1 and 10 grams per 100 c.c., but gradually decreases as the concentration increases. Below 1 gram per 100 c.c. the rate decreases very rapidly with the concentration.
It follows from this, in the light of what has already been said (p. [121]), that the action of living yeast on sugar follows the same course as a typical enzyme reaction, although in this case, as in that of yeast-juice, no information is given as to the exact nature of this reaction.