Moving them off the kitchen counter is only the first step. Here's how to prolong the life of leaveners.
Baking Powder and Baking Soda: 6 months Instant or Active Dry yeast: 4 months (in freezer)
Do replace baking powder and soda regularly. Despite most manufacturer claims of a shelf life of 1 year, our tests have proven they lose potency far sooner.
Don't keep yeast in the pantry—put it in the freezer to slow deterioration. And because yeast is a living organism, the expiration date on the package should be observed.
Over time, baking powder (comprised of baking soda, acid salt, and cornstarch) loses its ability to lift—sooner than many producers claim. We compared biscuits made with a newly opened can of baking powder to biscuits made with cans opened and stored for 1 month all the way up to a year. The rise of the biscuits began to decrease with the 6-month old powder and continued to decline to half the height of fresh at the 10-month mark. For best results, replace your baking powder (and soda) every 6 months.