Leaven is a substance, usually yeast or baking powder, that is added to dough or batter to cause it to rise. It can also refer to something that raises or lightens the tone of a piece of writing or speech.
Because of the lack of leavening agents in Passover desserts, eggs are the go - to ingredient for my recipes. (hungryrabbit.com)
That begins with baking at home, which the network and many members promote and teach, and if baking at home means beginning with brown bread leavened with bread soda, well and good. (realbreadireland.org)
For cakes leavened by egg whites, beat only to a soft - peak consistency to keep them from deflating as they bake. (betterbatter.org)