In this article:
- What is yeast and how is it made?
- What does yeast do?
- How does yeast work?
- What factors affect the effectiveness of yeast?
- My yeast didn't work! What now?
- How much does a "package" of yeast cost?
- Can I vary the amount of yeast in a recipe to make my dough faster or slower?
- I heard that when you double the recipe, don't double the yeast too. Is it true?
- What is the difference between active dry yeast and instant yeast?
- Can I use active dry and instant yeast interchangeably?
- RapidRise, instant, bread yeast… is there really a difference?
- What is golden yeast?
- What is fresh yeast?
- What's the best way to store yeast?
Yesterday- is a small addition to your recipe, but it raises some important questions. Whether you're a new bread baker or just want to brush up on your knowledge of yeast, here's our comprehensive guide to yeast baking.
What is yeast and how is it made?
Yeasts are single-celled organisms belonging to the kingdom of fungi. The yeast we use most often today, Saccharomyces cerevisiae, is one of the oldest domesticated organisms known to mankind: it has helped people bake bread and brew alcohol for thousands of years. Accordingly, the Latin translation of Saccharomyces cerevisiae is "beer sweet mushroom".
Saccharomyces cerevisiae is just one strain out of over 1,500 identified yeast species. But wait, there's more - literally. These 1,500 identified yeast species represent only about 1% of the world's yeast population; most species are still unnamed.
In order to have a reliable supply of yeast on hand for all our baking needs, manufacturers need to "tame" wild yeast - stabilize it, and in the process make it 200 times more potent than its wild counterpart.
Plant scientists working with a yeast producer identify certain characteristics of wild yeast that they find desirable, isolate them, and then replicate them. The resulting yeast is given a "training diet" (such as molasses or corn syrup) so that it can multiply and grow. Once the cells have replicated to critical mass - a process that typically takes about a week - they are filtered, dried, packaged and shipped to market.
What does yeast do?
The yeast makes the bread rise. Just as baking powder and baking soda make muffins and cakes rise, yeast makes all kinds of bread rise -sandwich bread,rolls,pizza base,artisanal bread, and more.
How does yeast work?
Since yeast cannot multiply without a good supply of oxygen, it stops multiplying once it is in the dough. Instead, he starts eating: sugar (sucrose and fructose) is his favorite food. If there is sugar in the dough, the yeast will eat it first; when it is absent, enzymes convert the starch in the flour into sugar that the yeast can consume; the flour is thus able to provide the yeast with a continuous source of nutrition.
By-products of feeding yeast are carbon dioxide, alcohol and organic acids. The carbon dioxide released by the yeast is trapped in the bread doughelastic gluten tissue; think about blowing up a balloon. Alcohol and organic acids spill over the dough and enhance the flavor of the baked bread.
As long as moisture and food are available, the yeast will eat and produce carbon dioxide, alcohol and organic acids. If your bread stops rising, it's usually not because the yeast isn't working (or is dead); this is because the yeast ran out of food or the gluten somehow "leaked out" and started to break down without retaining carbon dioxide.
What factors affect the effectiveness of yeast?
If you've ever baked bread, you've probably noticed that sometimes the yeast seems to work faster than other times. Yeast, like any living organism, is happiest when in comfortable conditions. For the yeast, this means plenty of food and moisture; proper pH (acid balance); and the right amount of heat. Yeast prefers temperatures between 70°F and 100°F; for convenience, and to produce the most flavorful bread, it is best to keep rising conditions at the cooler end of this range rather than the warmer, which can cause the dough to rise too quickly before it has a chance to develop its full flavor.
Salt and sugar can slow down yeast activity. Each of them is osmotic, which means that it can draw moisture from the yeast cells and thus negatively affect their functioning. We add salt to the yeast dough both for flavor and to slow down the work of the yeast; we don't want our bread to rise too fast. (See more here:Why is salt important in yeast bread?) Sugar is optional; a little makes the yeast happy, but too much - usually more than 1/4 cup to 3 cups of flour - slows down the yeast. Cinnamon is also a yeast inhibitor - you can't use more than 1 teaspoon per 3 cups of flour in the dough without significantly slowing the rise.
My yeast didn't work! What now?
There are many reasons why bread does not rise; weak or dead yeast is one of them. While you may have just purchased yeast, it may not have been stored or turned properly before purchase, so it may not actually be as fresh as you think.
A vacuum-sealed bag of yeast stored at room temperature will stay fresh indefinitely. Once the seal is broken, it should be placed in the freezer for optimal shelf life. (See "What's the best way to store yeast?" below.)
However, a vacuum-packed bag of yeast stored at high temperatures - such as in a hot kitchen in the summer or in a warm warehouse prior to delivery - will lose its effectiveness quite quickly. After some time, if stored incorrectly, the yeast cells will die. And if you use dead (or dying) yeast in your bread, it won't rise.
To make sure the yeast is active before mixing, see our blog post:How to test yeast for freshness.
Another reason yeast might not work: you may have killed it by using too hot water in your recipe; water hotter than 139°F will kill the yeast. But don't stress too much about the temperature; 139°F is much warmer than it feels comfortable to the touch. If you stepped into a tub of 139°F water, you would jump out quickly. As long as the water you combine with the yeast is comfortable for you, it will be comfortable for the yeast as well.
How much does a "package" of yeast cost?
You may find older recipes that call for "1 packet of active dry yeast". The package contained 1 tablespoon of yeast; this is now closer to 2 1/4 teaspoons as improved production methods now produce stronger, more active yeast.
Can I vary the amount of yeast in a recipe to make my dough faster or slower?
The amount of yeast used in bread dough has a significant effect on how quickly it rises. By reducing the number of yeast, you ensure a long, slow rise, making it more likely to produce a firm dough that will hold up to baking.
The more yeast in the recipe at the beginning, the faster carbon dioxide, alcohol and organic acids are formed. Alcohol, which is acidic, weakens the gluten in the dough and eventually the dough becomes "porous" and does not rise or rise very well.
By starting with less yeast, you reduce the amount of carbon dioxide, alcohol and organic acids released into the dough, thus ensuring that the gluten stays strong and the bread rises well - from the first rising in the bowl to the last rising in the oven.
Remember that this slow rising extends to the shape of the bread as well as the dough in the bowl. After forming the loaf, covering it and letting it rise again, it may take 2 hours or more to fully rise and be ready for baking instead of the usual 1 to 1 1/2.
Here are some tips to get you started. If you are an occasional bread baker, reduce the usual 2 to 2 1/4 teaspoons of instant yeast to 1/2 to 1 teaspoon, depending on how long you want the dough to rise before the final baking process. 1/2 teaspoon will give you plenty of flexibility, such as letting the dough "rest" for 16 to 20 hours; 1 teaspoon would be a good amount for a day or night (about 10 hours, at cool room temperature).
If you are using active dry yeast, which is not as strong as instant yeast, we will increase the range to 3/4 to 1 1/2 teaspoons.
I heard that when you double the recipe, don't double the yeast too. Is it true?
You can increase the size of most bread recipes by simply doubling, tripling, etc. all ingredients, including yeast. Depending on the recipe and rising time, you can use as little as 1 teaspoon or up to 2 1/4 teaspoons (sometimes more) of instant yeast per batch. pound (about 4 cups) of flour.
That said, many home recipes, especially older ones, use more yeast than this; so when you double or triple the yeast, you may find that your dough rises too fast - faster than you can easily handle. Additionally, if you increased your recipe by a factor of five or more, and also increased the amount of yeast by a factor of five, you need to keep in mind the time it takes to form a dough. You may find that the risen dough is beyond your shaping and baking capabilities. If so, make a note to reduce the amount of yeast next time.
What is the difference between active dry yeast and instant yeast?
In the old days, there was a significant difference between active dry yeast and instant yeast. Today, the difference is minimal, and the two can be used interchangeably - with slightly different results. First, let's look at active dry yeast.
Active dry yeast:The original classical active dry yeast production process involved rapid drying of the live yeast cells at high temperature. Result? Only about 30% of the cells survived. The dead cells "settled" around the living ones, making it necessary to "test" the yeast - dissolving it in warm water - before using it.
Today, active dry yeast is produced using a very gentle process, resulting in many more viable cells. So there is no need to dissolve active dry yeast in warm water before use - you can freely mix it with dry ingredients, just like you do with instant yeast.
Active dry yeast is considered more "moderate" compared to instant yeast. It slows down but eventually catches up to this point - think of a tortoise and a hare. Many bakers appreciate the longer rising times encouraged by active dry yeast; it is during the fermentation of the dough that the bread acquires its flavor.
Fleischmanns ogRed Starare the two brands of active dry yeast you'll most likely see in your supermarket.
Instant yeast:These yeasts are produced to smaller granule sizes than active droughts. Thus, with more surface area exposed to the liquid in the formulation, it dissolves faster and proceeds faster than active drying. While you can prove it if you want, it's not necessary; like active dry yeast, mixing it into bread dough along with the rest of the dry ingredients works well.
One caveat: In cakes with a high sugar content (usually more than 1/4 cup of sugar to 3 cups of flour), the sugar balances everything out, and instant yeast and active dry yeast will do the same. (For very sweet breads, you may consider usingSAF Gold Instant yeast; read more on this below).
Can I use active dry and instant yeast interchangeably?
Yes, they can be traded 1:1. We have found that active dry yeast is slightly slower than instant yeast when it comes to rising the dough; but with a long (2-3 hour) rise, the active dry yeast catches up. If an instant yeast recipe calls for the dough to "double in size, about 1 hour," you can mentally add 15 to 20 minutes to that time if you're using active dry yeast.
When a dough rises, judge it by how much it has risen, not by how long it takes; cold weather, low barometric pressure and many other factors affect the rising time of the dough, so take them as a guideline, not a hard rule.
For once, you may not want to use instant and active dry yeast interchangeably when you're baking bread in a bread machine. Since bread machines use a higher temperature to rise the dough, a 1:1 substitute of active dry yeast can cause the bread to rise too much and then collapse. When baking in a bread machine and replacing instant yeast with active dry yeast, reduce the amount of instant yeast by 25%.
RapidRise, instant, bread yeast… is there really a difference?
Bread yeast and instant yeast are the same yeast. RapidRise, Fleischmann's branded instant yeast, is also instant yeast, but different from SAF or Red Star.
We find that RapidRise is faster out of the gate than SAF or Red Star, but it gives up faster. And since we like to give our bread a slow rise (a long rise emphasizes the flavor of the bread), we like itSAF or Red Star.
What is golden yeast?
SAF Gold Instant yeast, another variety of SAF, is an "osmotolerant" yeast, ideal for sweet breads and all cakes with a high sugar content. SAF Gold works best when the amount of sugar is between 10% and 30% of the weight of the flour (this is the so-calledbaker's percentage"). So for a 3-cup loaf of bread (360g flour) you will choose SAF Gold if the sugar contains more than 3 tablespoons or up to about 1/2 cup. Remember that the more sugar, the slower the dough rises.
How does SAF Gold work? Sugar likes to absorb water; and when there is sugar in the bread dough, it draws water away from the yeast and makes the yeast thirsty. The yeast cells in SAF Gold are cultured to require less fluid to function, so they are better able to resist the water-hungry effects of sugar.
SAF Gold is best suited for sweet breads; for "lean" (low in sugar and fat) cakes, SAF generally recommends red label yeast.
What is fresh yeast?
Originally, fresh yeast was the only yeast option until dried yeast came on the market in the 1940s. It occurs in a moist, compact block with the consistency of clay. Fresh yeast gives baked goods a slightly sweeter, richer flavor compared to dry yeast. The downside, however, is its short shelf life: unlike dry yeast, it is very perishable and must be refrigerated. Even then, it usually only lasts about a week or two - open or unopened.
Despite these differences, both fresh and dried yeast serve the same function in baking, and fresh yeast will make your bread rise just as well as dried yeast. For more information on fresh yeast and how to convert between fresh and dry yeast, see our previous post:How to bake with fresh yeast?
What's the best way to store yeast?
We recommend transferring dry yeast (not fresh) to onesealed container(glass or acrylic) and store in the freezer for up to one year. If you are buying yeast in bulk (say a 1-pound brick vacuum packed), open it up; divide into three or four smaller portions and store each in a tightly closed container. A zip-top freezer bag works well.
When you're ready to use the yeast, take the bag or jar out of the freezer, put in what you need, and quickly put it back in the freezer. Yeast manufacturers say to let frozen yeast rest at room temperature for 30 to 45 minutes before use; Honestly, we're usually too impatient to do this, and we've never had a problem using yeast straight from the freezer.
Take yoursYesterday, so littlebaking. And reach our faithfulHelpline for bakersany time for more questions about yeast.
Cover photo: Rick Holbrook; food styling by Kaitlin Wayne.