587 



and dark ; the heat changes its starch into stiff gum and sugar and 

 dries out the moisture ; the brown color is due to chemical changes 

 known as caramelization. 



The heat in the oven should not be too great at first, or the out- 

 side of the bread will harden too quickly and the interior will not be 

 done before the crust is thick and dark; further, the gas expanding 

 in the crumb will be unable to escape through the crust and will lift 

 up the latter, leaving great holes beneath it. To prevent too rapid 

 formation of the crust, bakers sometimes moisten the tops of their 

 loaves before putting them into the oven or have devices for passing 

 steam over them during the baking. The steam also changes some 

 of the starch into a sort of gum on the top of the loaf and gives it the 

 shiny look so often seen in Vienna bread. The same effect can be 

 produced by moistening the top of the loaf just before it is taken from 

 the oven. Cooks sometimes get a similar result by spreading the 

 top of the bread lightly with butter. For ordinary purposes a baker 

 heats the oven to 400 or 500 F. and lets a pound loaf bake an 

 hour or an hour and a quarter ; small rolls perhaps half an hour. On 

 being taken from the oven, bread should be placed on slats or sieves 

 so that the air can circulate about it until it is thoroughly cooled. By 

 that time all the gas and steam which are likely to escape have done 

 so, and the bread may be put away. Some housekeepers wrap their 

 hot bread in cloths, but this is not advisable, not only because it 

 makes the bread taste of the cloth, but also because it shuts the steam 

 up in the loaf and makes it damp and clammy an excellent medium 

 for cultivating mold. 



Baking Tests. It has already been indicated that gluten is the 

 ingredient of the flour on which its bread-making properties chiefly 

 depend. All gluten is composed of two bodies called gliadin and 

 glutenin, and the principal factor which determines the character of 

 the gluten is the proportion of gliadin to glutenin in it. The gliadin, 

 a sort of plant gelatin, is the material which binds the flour particles 

 together to form the dough, thus giving it tenacity and adhesiveness ; 

 and the glutenin is the material to which the gliadin adheres. If 

 there is an excess of gliadin the dough is soft and sticky, while if 

 there is a deficiency it lacks in expansive powers. Many flours con- 

 taining a large amount of gluten and total proteid material, and pos- 

 sessing a high nutritive value, do not yield bread of the best quality. 



Some Minnesota experiments were planned to test the question 

 whether it is the starch content or the gluten content that determines 

 the bread-making quality of the flour. In certain cases the propor- 

 tion of starch in a normal flour was increased 10 to 20 per cent by the 

 addition of wheat starch, while in others it was decreased to the same 

 extent, and in still others 10 to 20 per cent of corn flour was added 

 to the wheat flour. In all cases the bread made from the flours con- 

 taining increased or decreased quantities of starch was compared with 

 that made from a like quantity of the normal flour. 



There was practically no difference in either the size or appearance 

 of the loaf as compared with that from normal flour. Similarly, 

 little difference was observed between the bread and from normal 



