Can I store baking powder in the freezer?

• Freezing will not affect the shelf life of baking soda but exposure to humidity and air will. Baking soda will keep about 12-18 months if stored on a shelf in its original box. It will keep much longer -almost-indefinitely- if sealed in a container that keeps out moisture and air. To determine whether it is still active, sprinkle a pinch into a small amount of vinegar. It should bubble vigorously.