FERMENTS AND MISCELLANEOUS PRODUCTS 85 



and the process can go on indefinitely. In the hydrolysis of 

 starch and sugars there is reason to believe that the sub- 

 stances combine with the acid, forming esters or similar com- 

 pounds, which are rapidly saponified by the water with the 

 regeneration of the acid. 



It is considered highly probable that the hydrolytic action 

 of enzymes takes place in a similar manner, i.e. that the 

 enzyme combines with the substance, and that the compounds 

 are subsequently resolved with the liberation of the ferment 

 in its original form. Indeed, it is claimed that compounds 

 of certain proteolytic enzymes with proteins have been iso- 

 lated, and that on digesting them with water at certain 

 temperatures, these compounds are resolved into peptones 

 and the original ferments. 



The products of fermentative changes are generally less 

 complex, i.e. they are of lower molecular weight, and contain 

 less potential energy than the original compounds. The com- 

 paratively few instances in which the reverse occurs cannot be 

 traced to the action of enzymes, and it is doubtful if they 

 should be regarded, strictly, as fermentations. The more 

 complex compounds produced are generally constituents of 

 the organism itself, and the energy required for their forma- 

 tion is probably derived from the oxidation or alteration of 

 some other compound or part of the compound, which is 

 transformed. 



The simpler fermentations may be generally referred to 

 one or other of the following types of chemical change : 



(1) Decomposition of a molecule into two or more simpler 

 molecules of the same or of different kinds, e.g. the conversion 

 of sugars into alcohol and carbon dioxide. 



C 6 H 12 6 -> 2 C 2 H 5 OH + 2 C0 2 



(2) Hydrolysis or simple decompositions in which the pro- 

 ducts combine with the elements of water, e.g. the inversion of 

 cane sugar. 



Ci 2 H 22 O n + H 2 -> C 6 H 12 6 + C 6 H 12 6 

 The diastatic fermentation of starch, decomposition of 



