94 ALIMENTATION. 



The process of raising or fermentation, called sometimes 

 panification, is characterized by several important changes 

 in the composition of the flour. These changes may take 

 place spontaneously from decomposition of the gluten and 

 its action as a ferment, or they may be induced, as is com- 

 monly the case, by yeast, or by gluten already in process 

 of decomposition, called leaven. The process of panifica- 

 tion involves three kinds of action, viz., the alcoholic, the 

 acetic, and the lactic acid fermentation. The alcoholic fer- 

 mentation is due to a decomposition of the small proportion 

 of sugar which the dough contains into carbonic acid and 

 alcohol. But this is not the only source of these principles. 

 A certain quantity of the starch is converted first into dex- 

 trine and afterward into sugar, which finally undergoes al- 

 coholic fermentation. The evolution of gas in this way 

 raises the dough, and forms little cavities in the bread, which 

 give it its peculiar porous character ; the elasticity and te- 

 nacity of the gluten allowing the dough to swell, and retain- 

 ing the gas in its interior. As gluten is particularly abun- 

 dant in wheaten flour, it is from this only that good light 

 bread can be made. 



When the dough has been sufficiently raised, it is put 

 into the oven and baked. The application of heat at first 

 increases the development of gas, but when the temperature 

 is raised to 212, the process of fermentation is arrested ; and 

 afterward the baking simply cooks and fixes the dough in its 

 expanded condition. The alcohol generated in the process 

 of raising is volatilized and driven off in the baking. 1 The 

 superficial portions of the loaf are exposed to a temperature 

 of about 375, by which they are hardened, forming the crust, 

 and a portion of the starch before unaltered is transformed into 

 dextrine. It is well known that the crust of bread contains 



1 A number of years ago a patent was taken out in England for a process for 

 collecting the alcohol evolved in baking bread. The project succeeded as far as 

 collecting the alcohol was concerned, but failed as a commercial operation. (PE- 

 REIRA, Treatise on Food and Diet, New York, 1843, p. 147.) 



