Yeast 101

by Jane Wangersky | March 20th, 2014 | Cooking Basics

yeastLast week I made a quick comment about how important it is to use quick yeast for the rapid bake cycle on your bread machine. (Also what to do if it’s too late — and by the way, my family did eat all the fried bread shards with cinnamon sugar.) So I thought it would be good to take a closer look at yeast — what it is, what it does, and the different types.

Yeast is a microorganism, and the kind known as baker’s yeast is used to leaven bread. Nothing is quite so good as yeast for turning flour and water into a light, soft, crisp-crusted bread. It feeds on the sugars in the ingredients, which don’t actually have to be “sugary” — potatoes or even the water they’ve been cooked in are enough. (That’s why you find these things in old bread recipes.) But what yeast needs, before anything else, is liquid to rehydrate it.

Several types of yeast are available to home bakers. lists those made by Fleischmann’s, which has made yeast for over 140 years.

Cake yeast or compressed yeast (pictured) is the old-fashioned kind — for a long time, it was the only kind you could buy, which is why old recipes often call for “a cake of yeast”. That’s not a random chunk, but ⅗ of an ounce. This yeast has to be either crumbled or dissolved in warm water before you add it to the other ingredients.

Most of us are more familiar with the powdery yeast that comes in tiny envelopes, usually called just “active dry yeast”. Each envelope equals one cake of compressed yeast. Today, active dry yeast also comes in glass jars — 2 ¼ teaspoons to one tablespoon of it equals an envelope or cake of yeast. Recipes created for bread machines often use less than an envelope, so a jar of yeast is handy for them. Yeast in unopened envelopes will keep on the shelf, away from heat and light, but a jar of yeast should be refrigerated after it’s opened.

Recently, quick or “rapid rise” yeast has been developed. says it “reduces rising time by as much as 50% by eliminating the first rise”.  So does specialty “bread machine” yeast.There’s an ongoing debate on whether the bread’s taste and texture is as good, but rapid rise yeast is certainly convenient. And we’re lucky to have such a selection of baker’s yeasts today, so that whether we want to stick to the old recipes as they’re written, or pick up the pace on our baking, there’s a yeast for it.

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