Yeast & Yeast Breads

If cooking is an art, then baking is a science. Baker’s that I’ve met have been some of the most intelligent and system-oriented individuals in the kitchen. A chef’s life is chaotic and he lives and breathes the chaos. A baker lives and dies by what he can measure and weigh. I find both to be equally impressive and it takes two different approaches to really understand either.

Today we are going to discuss some basics on yeast and yeast bread. Mastering yeast bread is something you may not achieve with this one article. But before you jump into the wide world of yeast bread and to a larger extent, baking, you need to understand what you are going up against and where you can apply know-how, skill and/or creativity to your process.

Yeast is a living organism, a one-celled fungus. There are various strains of yeast that exist virtually everywhere. Yeast feeds on carbohydrates, converting them to carbon dioxide and alcohol in an organic process known as fermentation.

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Yeast + Carbohydrates = Alcohol + Carbon Dioxide
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When yeast produces carbon dioxide gas during bread making, the gas becomes trapped in the dough’s gluten network. This trapped gas leavens the bread, providing the desired rise and texture. The small amount of alcohol produced by fermentation evaporates during baking.

Yeast is very sensitive to temperature. It prefers temperatures between 21’C and 54’C (70’F and 130’F) depending on the type of yeast. The range used in most bakeries is 32’C to 43’C (90’F to 110’F). At temperatures below 2’C (34’F) it becomes dormant and above 59’C (138’F) it dies.

Salt

Salt is used in bread making because it conditions gluten, making it stronger and more elastic. Salt also affects yeast fermentation. Because salt inhibits the growth of yeast, it helps control the dough’s rise. Too little salt and not only will your bread taste bland, but it will also rise too rapidly. Too much and the yeast will be destroyed. If you learn to control the amount of food for the yeast, the temperatures of fermentation and the amount of salt, you can control the texture of your yeast-leavened products.

Types of Yeast

There is yeast available in two forms for bakers: Compressed and active dry.

Compressed Yeast

Compressed yeast is a mixture of yeast and starch with a moisture content of about 70%. This is also referred to as fresh yeast. Compressed yeast must be kept refrigerated. It should be creamy white and crumbly with a fresh, yeasty smell. Do not use compressed yeast that has developed a sour odor or has become brown in color. Liquids that you are adding to fresh yeast should be at a temperature of 20’C and 24’C (68’F and 76’F)

Active Dry Yeast

Active dry yeast differs from compressed yeast in that virtually all of the moisture has been removed by air. The absence of moisture renders the yeast dormant and can be stored in dry storage without refrigeration for up to several months. Rehydrate active dry yeast in water with a temperature of 40’C (105-110’F). This is called activating the yeast. You want to see foam on the surface of the water with the yeast. This means it is active and ready to be added to your dough.

Instant Dry Yeast

Instant dry yeast is popular because there is no need to be activated before being added to the ingredients. The water in the bread formula will rehydrate the yeast. Some bakers prefer to activate the yeast before adding to the mixture. When does are mixed briefly or are very firm, such as bagel or croissant dough, instant dry yeast may not fully dissolve during mixing. In such cases, the yeast is moistened in 4 or 5 times its weight in water. Deduct this water from your formula. Beware of yeast clumping!

Yeast Conversion Table

If you are wanting to use fresh yeast in an active dry or an instant yeast with a fresh yeast formula, follow these factors below to reach your recommended weight.

For example, if you are wanting to convert a recipe that asks for 10g of active dry but you only have instant, you find the product by multiplying the active dry yeast by 0.75 which nets 7.5g.

Using This Skill Everyday

To this day I still find myself pulling out my conversion table from time to time. For the frequency (or infrequency) that I use yeast, I prefer active dry yeast. I would love to use fresh yeast however, I find that I cannot ever make enough dough to use it all. Experiment with different types of yeast and amounts. The only way you are going to get used to amounts is if you are constantly testing and trying new things. Do not be afraid to fail!