How to Test Yeast, Baking Soda, and Baking Soda For Freshness

As the holiday season is quickly approaching, we want to make sure everything you make in your kitchen is perfect. This means that you must be using fresh ingredients. So, let’s test your yeast, baking powder and baking soda for freshness.
To test baking soda, put one tablespoon in vinegar in a small bowl. Add 1⁄2 tablespoon of baking soda. Stir this. It should begin fizzing immediately.
To test baking powder, put 2 tablespoons of warm water into a bowl and stir in 1⁄2 a tablespoon of baking powder. The mixture should bubble and foam, but will not be as vigorous as the baking soda.
Next, we will test yeast. Dissolve 1⁄2 teaspoon of sugar in 1⁄2 cup of warm water. Stir in a packet of dry yeast or two tablespoons of instant yeast. Let this sit for 10 minutes. At this point, the yeast should bubble and expand. Wait another 10 minutes. It should be domed and light.
Now that you know all your leaveners are fresh, you are all prepared to take on this year’s holiday season!

The holidays are coming. You’re on a tight schedule. You want everything coming out of your kitchen to be absolutely perfect.

Photo Credit: King Aurthur Flour

What’s the first thing you need to do? Test your yeast, baking powder, and baking soda for freshness.

Let’s start with baking soda, which you’ll no doubt be using in all kinds of cookies, gingerbread, muffins, and other holiday treats.


To test baking soda for freshness:

Put 1 tablespoon vinegar in a small bowl.

Stir in 1/2 teaspoon baking soda. The mixture should fizz immediately – and quite vigorously, too.

What’s happening? Chemically speaking, baking soda (sodium bicarbonate) is a base. Vinegar is an acid. Base + acid = reaction.

If the two don’t fizz on contact – or the fizzing is gentle/minimal – it’s time to invest in a new carton of baking soda.

Next up: baking powder, the basis of cakes and cookies of all kinds, to say nothing of biscuits, pancakes, scones, muffins, quick breads… baking powder is our most popular chemical leavener.


To test baking powder for freshness:

Put 2 tablespoons warm water in a bowl.

Stir in 1/2 teaspoon baking powder. While you won’t see quite the vigorous reaction you get from baking soda/vinegar, the mixture should definitely bubble and foam.

What’s happening? 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.

Why is that? Double-acting baking powder, the kind we all purchase at the supermarket, reacts twice: first when it’s combined with liquid, and again when it hits the heat of the oven. Combining it with liquid in a recipe (e.g., with the milk in a cake recipe) gets the leavening started. And when you put the pan of cake batter into the oven, baking powder offers another burst of leavening power, thanks to the oven’s heat.

Finally, yeast – the friendly fungus that’s loved and feared in equal parts, due both to its sometimes fickle personality, and its enormous influence on your bread-baking.

Since yeast is such an important ingredient, you want to make sure it’s fresh and active. Here in the King Arthur Flour test kitchen we use SAF Red instant yeast on a regular basis; we don’t test its freshness because it comes vacuum packed, we store it in the freezer, and we use it quickly.

But for those of you who are occasional yeast bakers, relying on a three-pack of yeast from the supermarket (or wondering if that instant yeast you stashed in the freezer a year ago is still good) – it’s important that you test your yeast to see if it’s viable.

Find the full article here.


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