Once you reach Step 3 of your Sourdough Starter process and are refreshing the culture twice daily, you can collect generations of backup (some sources refer to leftover starter as “sourdough discard”) in a single sealed jar—you'll need a third, larger one—and refrigerate them for up to two weeks. Once you have amassed a cup or two of this sourdough discard, you can use it to flavor all sorts of doughs and batters by replacing a portion of the flour and/or liquid with this flavorful culture. Try it in these recipes for drop biscuits, pancakes, and crackers. (Note that this sourdough discard cannot be used in place of a leavener.)