e time the gluten of the dough is hardened by the heat, and the mass
remains porous and light, while the outer surface is darkened and formed
into a crust.

When the flour is of good quality, the dough well prepared, and the
bread properly baked, the loaf has certain definite characteristics. It
should be well raised and have a thin, flinty crust, which is not too
dark in color nor too tough, but which cracks when broken; the crumb, as
the interior of the loaf is called, should be porous, elastic, and of
uniform texture, without large holes, and should have good flavor, odor,
and color.

Meal or flour from any of the cereals may be used for unleavened bread,
but leavened bread can be made only from those that contain gluten, a
mixture of vegetable proteids which when moistened with water becomes
viscid, and is tenacious enough to confine the gas produced in the
dough. Most cereals, as barley, rice, oats, and corn, some of which are
very frequently made into forms of unleavened bread, are deficient or
wholly lacking in gluten, and hence cannot be used alone for making
leavened bread. For the leavened bread, wheat and rye, which contain an
abundance of gluten, are best fitted, wheat being in this country by far
the more commonly used.

172. Changes during Bread Making.--In bread making complex physical,
chemical, and biological changes occur. Each chemical compound of the
flour undergoes some change during the process. The most important
changes are as follows[64]:

1. Production of carbon dioxid gas, alcohol, and soluble carbohydrates
as the result of ferment action.

2. Partial rupturing of the starch grains and formation of a small
amount of soluble carbohydrates due to the action of heat.

3. Production of lactic and other organic acids.

4. Formation of volatile carbon compounds, other than alcohol and carbon
dioxid.

5. Change in the solubility of the gluten proteins, due to the action of
the organic acids and fermentation.

6. Changes in the solubility of the proteids due to the action of heat,
as coagulation of the albumin and globulin.

7. Formation and liberation of a small amount of volatile, nitrogenous
compounds, as ammonia and amids.

8. Partial oxidation of the fat.

173. Loss of Dry Matter during Bread Making.--As many of the compounds
formed during bread making are gases resulting from fermentation action,
and as these are volatile at the temperature of baking, appreciable
losses necessari