CHAPTER VII 



FERMENTS AND MISCELLANEOUS PRODUCTS 



Ferments. Frequent reference has been made in previous 

 chapters to the action of ferments. It may be well to explain 

 briefly what these are and how they act. 



The ferments with which we are here chiefly concerned are 

 those known as enzymes. They are complex, nitrogenous 

 substances of uncertain composition, but they are believed to 

 be homogeneous compounds of an albuminous nature. They 

 are present in seeds and starchy vegetables, and in the gastric 

 juice and other digestive fluids of animals. They cause 

 various chemical changes, which take place in the processes of 

 germination, translocation, and digestion. These changes are 

 known generally as fermentations. 



The term "fermentation" is derived from the French 

 fervere, " to boil." It was originally applied to the changes 

 produced by organisms like yeast, which, when added to 

 brewers' worts, transform the sugars into alcohol and carbonic 

 acid gas. The frothing due to the evolution of the gas produces 

 the appearance of boiling. The term is now applied not 

 only to similar changes produced by other organisms even 

 those in which gases are not evolved but also, as indicated 

 above, to those due to the action of enzymes. 



There is reason to believe that all fermentations are due 

 ultimately to the action of enzymes, and not, as was formerly 

 supposed, directly to the vital activity of the organisms. It is 

 known, for instance, that the chemical changes which are inci- 

 dental to the growth of yeast in sugar solutions can be brought 

 about by the juices extracted by pressure from the organism 

 when the cells are thoroughly disintegrated. The same is true 



83 



