Yeast bread rises through the action of baker's yeast, strains of Saccharomyces cerevisiae carefully selected for the commercial baking industry. The CO2 produced during fermentation causes the bread to rise, producing the honeycombed texture characteristic of yeast breads. The alcohol evaporates during baking.
Yeast bread is made from a mixture of flour, sugar, salt, milk or water, yeast, and sometimes butter or oil (figure 32.6). Packaged baker's yeast that can be reconstituted in warm water is readily available as pressed cakes or dried granules. An excess of yeast is added to enable adequate production of CO2 in a time period too short to permit multiplication of spoilage bacteria.
Sourdough bread is made with a combination of yeast and lactic acid bacteria. Alcohol and CO2 are produced as well as lactic acid, giving the bread its sour flavor.
Molds contribute to the flavor and texture of some cheeses, as already discussed. In addition, many traditional dishes and condiments used throughout the world are produced by encouraging the growth ofmolds on food (table 32.3). Successions of naturally occurring microorganisms are often involved. The microbiological and chemical aspects of many of these traditional foods have not been extensively studied.
Was this article helpful?