178 



PHYSIOLOGY OF BACTERIA 



The lower half of this table shows the composition 

 of the medium and yeast crop, eleven hours later. The 

 balance is not perfect, owing to the enormous bulk of 

 the liquid, and to inaccuracies involved in determining 

 the evaporated alcohol and carbon dioxide. There is 

 an unaccounted loss of 16 kg. of inorganic matter, 

 and of 87 kg. of organic matter, or about 4% of the total 

 organic matter involved. 



A summary of all analyses made by Claassen in short 

 intervals bears out the claim of Balls and Brown that 

 alcohol can be used for growth by the yeast. After 

 eight hours, the wort contains only 0.054% sugar. 

 During the next three hours considerable growth still 

 takes place, while the alcohol concentration decreases 

 much faster than can be accounted for by evaporation. 



Table 40. — Utilization op Sugar and Alcohol during Yeast 



Growth 



The alcohol :C02 ratio, for this reason, is only 0.52 

 instead of the theoretical 1.04 for alcohol fermentations. 



The yeast solids (516 kg. — 82 kg. seed yeast) contain 229 — 49 

 kg. of protein which may derive from the nitrogenous matter of 

 molasses and malt sprouts, and 251 — 27 = 224 kg. non-nitrogenous 



