Holidays

“Passover celebrates one of the most important events in Jewish history: the Exodus from Egypt, which led to the birth of the Jewish nation. In memory of the Jews who fled in such a hurry that their dough did not have time to rise, and following the injunction in the Torah that ‘Seven days shall there be no leaven found in your home,’ foods considered leaven (hametz) are forbidden. Fermenting agents such as yeast are forbidden, as is the fermentation of five types of grain--wheat, barley, rye, oats, and spelt--which are named in the Torah and can ferment.”

--Claudia Roden, “The Book of Jewish Food”