From The Food Encyclopedia by Jacques Rolland and Carol Sherman
1. a leavener for bread made from flour and water and allowed to ferment for several hours or days to encourage the growth of wild yeast present in the flour. Many bakers add some commercial yeast to the mixture at the beginning to start the fermentation process quickly. As the sponge ferments, it takes on the characteristic sour flavor that is so prized in sourdough breads and pain au levain. The yeast in the starter can be kept alive in two ways: any leftover sponge can be kept and regularly "fed" with more flour and water and used when it's convenient, or a piece of the leavened bread dough can be added to the next batch of dough and allowed to grow in that environment. 2. an old-fashioned dessert made with gelatin and fruit juices or purées. The gelatin mixture is cooled until almost set, then beaten until frothy and combined with stiffly beaten egg whites. Whipped cream is often added to the mixture to give it a richer dimension. The dessert is light, airy and quite malleable, as the gelatin can be flavored with any kind of fruit.
