CO2 and Fermentation

Influence of Carbonic Acid on Fermentation  

By Hugo Ortloff as reported in American Brewers’ Review  1900

1. Carbonic acid exercises in some cases a slightly favorable, in others a slightly retarding influence upon the inverting capacity of the several yeast types.  

2. Carbonic acid seems to make the fermentation of dextrose more difficult. 

3. In fermentation in a current of carbonic acid less alcohol is found, not only as an absolute quantity, but also by comparison with the fermented cane sugar. 

4. The influence of carbonic acid upon the production of acid is neither altogether favorable nor altogether retarding.

5. The energy of multiplication of the cells is slightly impaired by carbonic acid. 

6. The capacity of multiplication also is impaired by carbonic acid, except in two cases. 

7. The fermenting energy is also impaired by carbonic acid. 

8. The fermenting capacity, on the other hand, is largely increased by carbonic acid in nearly all cases.

9. The single cell, in the current of carbonic acid almost invariably produces more alcohol than in ordinary fermentation. 

10. In fermentation in the current of carbonic acid the single cell also forms more acid than in ordinary fermentation. 

As to the main question whether carbonic acid exercises a downright retarding or a favorable influence upon fermentation, the author refers to the views of Delbrueck and Hansen. 

Delbrueck concluded from his experiments that carbonic acid not only impaired the growth of yeast, but also retarded the fermenting activity.  

Hansen, on the contrary, claimed that carbonic acid not only failed to impair the fermenting activity of the cells, but even stimulated it.

A series of experiments of the most exact character justifies the conclusion, according to the author, that . . .

11. Viewing the total effect, carbonic acid apparently impairs fermentation, but the fermenting capacity of the yeast cells is increased, in accordance with the view expressed by Hansen.

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