In. bread-making much happens. Science now explains the changes that occur. Yeast grows while in warm dough. This causes a fermentation. Carbon dioxid gas is formed, also alcohol. The gas and steam expand the loaf until high heat in baking checks further growth of yeast. This heat vaporizes the alcohol, so it is not left in the bread.

Besides the yeast that raises bread, other organisms are present. Many of these may produce undesirable effects, one of which is the souring of bread. This happens when bread has been allowed to rise too long or bread sponge is left uncovered. Active yeast and, after rising, prompt baking in a well-heated oven tend to prevent bread from souring or falling. Heating the milk used lessens such danger, as does warming flour before mixing bread.

Baking bread may not destroy all germs present, but it lessens the probability of their further activity. As molds and bacteria readily grow in bread, it requires proper care. It needs to be kept in a clean, ventilated box, not exposed to dust nor handled by diseased persons. Bread not made at home should be promptly wrapped after cooling.

Science found in examination of 100 loaves from 100 shops 14 unwrapped loaves each coated with over 10,000 bacteria.

11 wrapped loaves from clean shops averaged only 371 bacteria each.

85% wrapped had less than 1000 bacteria; 62% unwrapped more than 1000.

(From the Journal ofthe American Medical Association, July 6, 1912).

For children bread needs to be baked slowly at first. It is thus made drier. After the crust is formed the moisture is retained. Cooling bread uncovered in clean, fresh air makes the crust hard. In the crust itself some of the starch is converted into soluble form that tastes sweeter and is more readily digested. This happens also in toasting bread, especially in oven-toast.