DEPARTMENT OF BIOLOGY
These first two are also on the page of "molecules." In a liquid, molecules are close together. In a gas, molecules are farther apart. When a gas is heated, the molecules move even farther apart. Sugar in bread dough is dissolved in water, in a liquid. When yeast converts it to CO2, it expands--making bread dough rise. When bread is cooked, the gas bubbles expand further. gas at low and high temperatures oven spring Gas bubbles, trapped in bread dough, expand rapidly during cooking, causing "oven spring." When the starch and protein gelatinize, the structure solidifies, and the gas escapes.
last updated: Aug. 11, 2010