Strains of the yeast Saccharomyces cerevisiae that are used in bread-making to enable the dough to rise. Water is added to flour, which activates the amylase enzymes that hydrolyse the starch in flour to glucose. Baker’s yeast is then added, which uses the glucose as a substrate for alcoholic fermentation. The carbon dioxide produced from the yeast’s fermentation causes bubbles to form in the dough; these become larger during heating in an oven, giving bread its typical texture. As baking proceeds, the heating removes the carbon dioxide and alcohol.