Bread unpredictable since the steam is not produced until the bread is baked. Steam leavening happens regardless of the raising agents (baking soda, yeast, baking powder, sour dough, beaten egg white) included in the mix. The leavening agent either contains air bubbles or generates carbon dioxide. The heat vaporises the water from the inner surface of the bubbles within the dough. The steam expands and makes the bread rise. This is the main factor in the rising of bread once it has been put in the oven. CO generation, on its own, is too small to account for the rise. Heat
Sliced bread was also intended to counteract a rise in the price of bread, caused by the Office of Price Administration's authorization of a ten percent increase in flour prices. In a Sunday radio address on January 24, New York City Mayor LaGuardia suggested that bakeries that had their own bread-slicing machines should be allowed to continue to use them, and on January 26, 1943, a letter appeared in "The New York Times" from a distraught housewife: I should like to let you know how important sliced bread is to the morale and saneness of a household. My husband and four children