BREAD, BUTTER, ETC. 65 



obtaining it. Bread being mixed, but for some reason 

 left unbaked, in consequence of a slight fermentation spon- 

 taneously taking place, showed him in what direction to push 

 his inquiries, and gradually the multiplicity of processes 

 now in use, were arrived at. 



It may be well to note some of the more obvious changes 

 that take place in flour, as a consequence of that kind of 

 fermentation involved in raising bread. Flour of wheat is 

 made up principally of starch and gluten, with a proportion 

 of sugar. These substances undergo no change so long as 

 kept entirely dry. When moistened, however, in a favorable 

 temperature, a spontaneous change commences called fer- 

 mentation. This requires considerable time, and is uncer- 

 tain in its development. For this reason, some form of yeast 

 or " risings," is added to start the fermentation at once, and 

 carry it forward with certainty. The effect of this fermenta- 

 tion is first to convert the sugar of the flour into alcohol and 

 carbonic acid gas, just as in the distiller's vat, the sugar of 

 the molasses, when diluted with water and a ferment added, 

 produces the same substances. The carbonic acid in the 

 latter case escapes from the fermenting mass in minute bub- 

 bles of gas rising through the liquid, and the alcohol is 

 afterward distilled in connection with water in the form of 

 rum. In the case of the bread, the gas cannot escape in 

 consequence of the tenacity which the gluten gives to the 

 mass, and the minute bubbles expand or raise the bread in 

 every part, giving it its peculiar porous character, which 

 baking fixes and makes permanent. The alcohol is driven 

 off by the heat required in baking. 



The principal change, thus far, is to deprive the flour of 

 its saccharine matter, and it loses that sweet and relishing 

 taste which unfermented bread possesses. Other changes 

 supervene, and, in fact, take place simultaneously with the 

 one here described. The starch of the flour is attacked and 

 decomposed in some way not well understood, though it is 

 probable that by the action of the ferment' the starch is 

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