Baking powder should be kept dry in a sealed container to prevent it from losing its potency. To test it, pour 50 mL (1/4 cup) hot tap water over 2 mL (1/2 tsp.) of baking powder. If fresh, it will bubble actively. If this doesn't happen, discard and buy a new supply.

 Homemade breads contain no preservatives. Use them within a day or two or freeze in airtight bags. Breads stored in a refrigerator will stale more quickly than if stored at room temperature.