When the bread has become light enough, it is put into the oven to be baked.
The baking serves the double purpose of cooking and thus making the starch appetizing, and of killing the yeast germs so that they will carry their fermentation no further.

Bread that has not been thoroughly baked, if it is kept too long, will turn sour, because some of the yeast germs that have escaped will set to work again.
[Illustration: A THOROUGH BAKING, AND A VALUABLE CRUST Note the cleanly way of handling the food.] That part of the dough that lies on the surface of the loaf, and is exposed to the direct heat of the oven has its starch changed into a substance somewhat like sugar, known as _dextrin_, which, with the slight burning of the carbon, gives the outside, or crust, of bread its brownish color, its crispness, and its delicious taste.

The crust is really the most nourishing part of the loaf, as well as the part that gives best exercise to the teeth.
Making Bread with Soda or Baking-Powders.

Another method of giving lightness to bread is by mixing an acid like sour milk and an alkali like soda with the flour, and letting them effervesce[8] and give off carbon dioxid.

This is the mixture used in making the famous "soda biscuit." Still another method is by the use of _baking-powders_, which are made of a mixture of some cheap and harmless acid powder with an alkaline powder--usually some form of soda.