S22 Ohservations on Fermentation. 



which vegclablcs consist ; he confines liimself to the three 

 kinds of tbrnienlalion, called {\\cpannary, the vinous, and 

 the aietons. We shall follow the author in his develop- 

 iTient, and make some observations on the most interesting 

 of his facts, 



\st. Of the Pannary Fermentation. 



The making of bread, the food of almost all Europeans, 

 is a domestic chemical operation, since in it those sub- 

 stance:^ which are the most essential to the sustenance of 

 man undergo a change in their nature. These substances 

 are found united in the meal of the farinaceous seeds, es- 

 pecially in those of wheat, which furnishes the best bread. 

 M. Chaptal has found this latter farina to consist of starch, 

 gluten, mucilage, and sugar. \Vc may add to them the 

 ferment, the vegetable albumen, calcareous phosphate. Sec. 

 which must be reckoned in the number of materials which 

 compose it. What sliare has each of these principles in 

 carrying on the pannary fermentation ? It is generally be- 

 lieved that the farina being reduced into a paste, the mu- 

 cous saccharine |)rinciple undergoes the vinous fermenta- 

 tion, that the starch has a tendency to become acid, and 

 that the gluten and alliUnien enter into putrefaction. 



I cannot einirely accord with this doctrine. It appears 

 to me to be more correct, to suppose that the ferment, after 

 having cor.reited the sugar of the iarina into carbonic acid 

 gas, and into alcohol, changes this into acetic acid ; that 

 at the same time the gluten and the albumen are in part de- 

 composed, acetic acid is again produced, some ammonia, 

 and more carbonic acid gas, &c. ; and that, the starch 

 unitinsc with the undecoiiiposed gluten, there results a 

 c(jmpound, the further alteration of which is prevented by 

 the action of fire, which combines siill more intimately 

 these principles. 



This theory of the pannary fermentfition seems to me to 

 be supported by the following facts. 



1st. Those farinse which are deprived of the fermenting 

 principle, or those which scarcely contain any of it, al- 

 ways aflbrd heavy bread, although the muco-saccharine 

 principle forms a part of them ; for this substance not be- 

 ing a fermentable principle, it cannot fern)ent of itself, 

 although it does so by nieans of a ferment. Thus, it is 

 customary to add to the dough a leaven, taken from bread 

 aheadv fermented, or ihe yeast of beer, as is the practice 

 in Paris. 



2. Dough is always acid, notwithstanding that the vola.- 



tile 



