Test the Freshness of Your Leavening Agents

So how long has it been since you used your baking powder, soda or that yeast you have in the cupboard... be honest. If it's been longer than you want to admit, it might be worth your time to make sure they are still fresh and will give your baked goods the lift they need. Nothing is worse then spending all morning in the kitchen and have your efforts not turnout as planned.

How to Test Your leavening Agents:
Baking Soda
Baking soda is used in all kinds of cookies, muffins and other holiday treats.

• Put 1 tablespoon vinegar in a small bowl.
• Stir in 1/2 teaspoon baking soda. The mixture should fizz immediately and quite vigorously. If this is not the reaction you are getting it's time for a new box
• Baking soda (sodium bicarbonate) is a base and vinegar is an acid. Base + acid = reaction.

Baking Powder
Baking powder is used in cakes, biscuits, pancakes and many quick breads, it's the most popular chemical leavening agent.

• Put 2 tablespoons warm water in a bowl.
• Stir in 1/2 teaspoon baking powder. The mixture should bubble and foam just not quite as much as the baking soda and vinegar.
  
• Baking powder is a combination of baking soda (base) and cream of tartar (acid), with some cornstarch thrown in to buffer the mixture and prevent an immediate reaction. Since baking powder already includes acid, you don’t need to combine it with acid (vinegar) to see if it’s fresh; you simply need to get it wet.
• Double-acting baking powder, reacts twice: first when it’s combined with liquid, and again when it hits the heat of the oven.

Yeast
Yeast if stored in the freezer will last years. I use mine so fast it's not an issue for me. If baking bread is an occasional event in your household then you will want to test it for freshness.

• Dissolve 1/2 teaspoon sugar in 1/2 cup warm water.
• Stir in a packet of active dry yeast; or 2 teaspoons instant yeast.
• Go away. Come back in 10 minutes.
• There should  be bubbles, not a huge amount of them.
  

If the yeast is fresh use it in your bread. Look at the recipe and reduce the amount of liquid in the recipe by 1/2 cup. Then go ahead and add your tested yeast to the bread and expect great results.

Sources:
King Aurthur Flour
PJ Hamel November 6, 2015