Q TRANSACTIONS OF WAGNER 



82 



THE CHEMISTRY OF BREAD-MAKING 



empirical formula as starch and cellulose. These carbohydrates are present 

 in the following approximate proportions : 



Starch 63.00 to 68.00 per cent. 



Cellulose 2.00 to 3.00 per cent. 



Dextrin 2.00 to 2.50 per cent. 



Sugars 1.25 to 1.75 per cent. 



Whole wheat flour contains in addition about three per cent, of lignin, a 

 more resistant form of cellulose. 



The part played by the carbohydrates of flour in the chemistry of bread- 

 making is important. Much of the starch, it is true, is unchanged, except for 

 the rupturing of the granules by the combined effect of heat and moisture and 

 the production of a small amount of soluble starch by this same cause as well 

 as by the action of enzyms. The crust or outer surface of bread consists of 

 altered starch, and the sugars contribute to the development of the carbon 

 dioxid or leavening gas when yeast is used. The cellulose and dextrin play a 

 passive part, both probably remaining unchanged. 



Ash. — This term includes all the inorganic constituents or salts found in 

 foods, which are important elements in the development of bones and teeth, 

 and indispensable to many of the vital fluids, such as blood and digestive 

 secretions. The ash of wheat contains small amounts of all the elements 

 commonly recognized as of essential value in nutrition; among these are 

 potassium, sodium, calcium, magnesium and iron combined as phosphates, 

 siKcates, suKates, and chlorids. They play but a small part of the chemical 

 reactions of bread-making, in which they are reinforced by the sodium chlorid 

 or salt added for seasoning. It is possible that they do play an important, if 

 obscure, part in activating the ghadin and glutenin to form the gluten, as was 

 previously mentioned. Their most important function, aside from this, is 

 in supplying the yeast with some of its necessary mineral food, without which 

 its growth would cease and the leavening power be impaired. 



To these basic proximate principles of the flour used in bread-making must 

 be added, in the special case of milk bread, the fat, proteins, carbohydrates, and 

 salts of the added milk. While these differ slightly, the general reactions re- 

 main unaffected. Also the fat used for shortening and the sugar often used to 

 hasten the growth of the yeast, must be kept in mind as reinforcing materials 

 naturally found in the flour. 



Having considered and described all the potential chemical factors of the 



