Dry Yeast

Table of Contents


Dry yeast for general baking in ovens (at home) is normally dry baker’s yeast. The use of fresh yeast (yeast cakes or compressed yeast) in home baking is rare – recipes or formulas that mention fresh yeast are old, although some commercial formulas may still refer to fresh yeast. In 1999, Beth Hensperger, in her Bread Bible said that the yeast on the market for the home baker included compressed cakes of fresh yeast and three dry yeasts:

  • active dry yeast. The inner yeast cells are active, unless the yeast has dried out and expired. It has to be activated in warm water, and fed with sugar or starch;
  • instant – as of 1999, a special product from Europe. It has more active cells, and does not have to be proofed in water – it is activated by contact with any moisture in the dough; and
  • quick-rise and/or rapid-rise.

Beth Hensperger also mentioned, in her Bread Bible, the appearance of dry yeast products labelled bread machine yeast manufactured by Fleishmann’s and Red Star. At that point she said it was finely granulated and coated with ascorbic acid. If the manufacturers told her how bread machine yeast actually differed from instant and quick/rapid rise dry yeast, she did not say.

Many home baking books have been written with active dry yeast as the yeast to be used.

Recipes for home bakers generally use volume measurements.

Yeast: Science, Technical, historical

Yeast is a eukaryotic (single-celled) microorganisim. Yeasts are funguses. There are hundreds of species. The principal species used in processing carbohydrates in baking, brewing, and wine-making, and as a food product (nutritional yeast) is Saccharomyces cerevisiae (“S. cerevisiae”). Many varieties (“strains”)of S. cerevisiae are used in food processing, and are grown, processed, and marketed in different ways. Brewers differentiate: yeasts that form a film on top of a wort like S. cerevisiae are ale yeasts yeasts that accumulate and ferment on the bottom are yeasts for lagers.

The beginning of brewing and baking seem to be historically related. Yeast infected grain mashes. Yeast consumed starch (fermentation) producing carbon dioxide and alcohols. Carbon dioxide trapped in webs of gluten, makes bread rise. Alcohols flavour bread, and have other purposes. These accidents started cycles of experimentation, learning and imitation.

At some points, bakers obtained yeast by buying by-products of brewing. Industrial yeast production in the 18th and 19th century produced compressed or “caked” fresh yeast in blocks or “cakes” to industrial bakers.

In 1999, yeast manufacturers were introducing new dry yeast products to the market. Mergers and acquisitions realigned brands. The American brand Red Star was sold to the European manufacturer The proliferation of types and names arose because manufacturers used different techniques and marketing terms. The manufacturers do not explain (to retail consumers and home bakers) how rapid/quick-rise, instant yeast and bread machine yeast products are made, or how they. Bakipan, another American brand acquired by Lesaffre, for instance, says that its “Fast Rising Instant Yeast [is] … cake yeast in a semi-dormant state. The drying process in its manufacture reduces moisture content, giving it a longer shelf life than cake yeast while retaining optimum activity. … Bakipan® Fast Rising Instant Yeast is a fast-acting yeast that can shorten the rise times for traditional baking …” Specifications and methods are not noted on the packaging or published widely – perhaps only for some customers.  The manufacturers don’t, according to what home bakers say on the Web, respond to inquiries from home bakers.

Dry Yeasts


For cooking and baking measurement of yeast and other ingredients for home cooking was and is usually by volume. The teaspoon is the normal unit of measurement. A teaspoon is exactly 1/3 of a Tablespoon. The exact metric conversion, to the nearest .1 millilitre is 4.9 ml. It is common for spoons to be marked indicating that 1 teaspoon is 5 ml., 1 Tablespoon is 15 ml., ½ tsp. is 2.5 ml., etc.

Active Dry

Active dry yeast was developed in the 1940s, perhaps as a consumer product for home bakers. Active dry yeast was durable for months or years, unlike the compressed fresh yeast used by industrial bakers. Active dry yeast was and is manufactured by drying a yeast culture. The dried yeast was made up of “grains”resembling fine sand, which are actually clusters of thousands of yeast cells. The exterior of the grains was/is made of dead cells. The live dormant interior cells can be activated by putting the dry yeast in warm (not hot) water. This product had and has a serious expiry date. Active dry yeast was and is sold in 1/4 oz. (U.S.) packets. In the US a packet was 1 Tbsp., and for some years 2.5 tsp. As of 2022 is 2.25 tsp. Old packets of old style active dry yeast are gone.

Bread recipes from the 1940’s until the introduction of the other dry yeast varieties refer to active dry yeast. Many specify with amounts of active dry yeast in packets or by measuring spoons, by volume. Active dry yeast is measured to the nearest quarter teaspoon in many home baking recipes and bread machine recipes.

Instant Yeast

Instant dry yeast grains are smaller than grains of active dry, and chemically coated in ascorbic acid (Vitamin C) and sugar. Instant yeast activates on contact with the water when the dry ingredients are mixed with the wet ingredients, and almost never needs to be activated or prehydrated to propogate. See All About Dried Yeast, What is Bread Machine Yeast, the King Arthur flour Ingredient Guide, the King Arthur web article All About Yeast, and the King Arthur blog post “Which Yeast to Use”. See also Commercial Yeast in Fresh Loaf Baker’s Handbook, and What’s the Difference between Active Dry Yeast and Instant Yeast. For the history of baking yeast, and the ways it has been presented, Lesaffre’s Explore Yeast pages are informative.  A leading baking industry paper on instant dry yeast: Lallemande’s Update, Volume 2 # 9.

Instant yeast, like active dry yeast, was and is sold in 1/4 oz. (U.S.) packets by some manufacturers.

Beth Hensperger mentioned instant yeast sold as Regular Instant and Special Instant in her 1999 Bread Bible. Looking back from 2022, it is not possible to identify the manufacturer. Lesaffre brought instant yeast to the market in the U.S. under its own SAF brand. It manufactures and promotes SAF-Instant Red and SAF-Instant Gold. The Gold product is osmo-tolerant, and said to be “designed especially for doughs high in sugar (sweet breads)”. Lesaffre distributed SAF brand yeast to home bakers in the US through quasi-wholesale vendors like King Arthur Flour as a specialty baking product. Generic and store-branded instant yeasts are available.

Increasingly, general bread recipe books are written for instant yeast, also by volume.

Peter Reinhart said that instant dried yeast can be substituted for compressed fresh and active dry yeast for home bread baking, and for artisanal recipe uses. He came to accept that instant dry yeast should be rehydrated for artisanal breads in Artisan Bread Every Day at p. 13 (although fermentation should be slowed down with refrigeration). Other writers agree

  • Peter Reinhart, Crust and Crumb (Ten Speed Press, 1998);
  • Peter Reinhart, The Bread Baker’s Apprentice (Ten Speed Press, 2001);
  • Peter Reinhart, Artisan Bread Every Day (Ten Speed Press, 2009);
  • Robert DiMuzio, Bread Baking; An Artisan’s Perspective (Wiley, 2010).

Some recipe and baking books suggest letting the yeast and ingredients warm to room temperature. Some  sources suggest that keeping yeast cold, including dried yeast, slows it down. Reinhart noted that instant yeast is potent but slow to awake in The Bread Baker’s Apprentice at p. 32. refrigeration preserves the product.

Quick-rise, Rapid-rise

Quick-rise/rapid-rise products are dried and coated differently than instant yeast, but have smaller individual grains than active dry. See: Yeast: Dry vs. Rapid-Rise and the thread “Fast Active Fleishmann’s vs. SAF Instant” (about pizza dough). The equivalences are debated in forums like Instant Yeast vs. Fleishmann’s Rapid-Rise. These yeasts were and are sold in 1/4 oz. (U.S.) packets by some manufacturers. Books on artisinal bread baking do not distinguish quick-rise/rapid-rise yeast from instant dry yeast.


Yeasts, once they activate, ferment and propogate, pick up speed and hit a peak. Some compressed and active dry yeasts have a second peak – home wine makers and home beer makers encounter this with their yeasts which have a vigorous first fermentation and a secondary fermentation. Bakers may time their bulk fermentation and final proof to take advantage of each. I found a graph on SAF Instant dry yeast gas production (with the Cyrillic text and the red line for SAF in the post by Mariana January 2, 2018 in the forum Difference in Yeast Brands). I have not found comparison graphs for other instant dry yeasts.

Converting Active Dry to Instant

In 1999, Beth Hensperger, writing in her Bread Bible said that a quarter ounce (US Units) “packet” of active dry yeast was a Tablespoon. Manufacturing has changed; modern active dry yeast grains are finer, and the product is more dense. Modern active dry yeast is still sold in quarter ounce packets. Due to changes for a few years a quarter ounce converted to 2.5 tsp. which is .83 Tbsp. More recently, leading brands Fleishmann’s, Red Star (Lesaffre), SAF (Lesaffre) state that the quarter ounce packet contains 2.25 tsp.

The amount of current active dry yeast to substitute for a packet of active dry in a recipe can be determined easily:

  • A quarter ounce packet is still a quarter ounce packet;
  • A home baker with a jar of modern active dry yeast can scoop 2.25 tsp. (or 2.5 tsp) of modern active dry to substitute for a “packet” of active dry in an old recipe.

Converting a specific amount by volume – e.g. 2 tsp. – of active dry yeast in an old recipe to modern active dry yeast, or to instant yeast will involve parsing the recipe to sell what an author meant when the recipe as published, and a little math.

Many online converters do not use accurate information about the products, or make rounding errors.

Instant yeast has smaller particles; it is denser. 1 tsp. of instant is heavier than 1 tsp. of active dry (although modern active dry is denser than active dry used to be). Instant has more active yeast cells. It reproduces faster and starts fermenting faster. Substituting dense and “potent” instant yeast for active dry usually means less volume and a decrease in weight. The bakers’ rules of thumb for converting instant and (modern) active dry yeast by volume were:

  • 5 parts active dry = 4 parts instant. 1.25 tsp. active dry = 1 tsp. of instant , per Peter Reinhart; and
  • 4 parts active dry 3 parts instant. 4 tsp. active dry = 3 tsp. of instant.

Peter Reinhart says that 1 tsp of active dry yeast is 0.1 oz. (US). Reinhart’s table has 1 tsp of instant yeast at 0.11 oz.

Product (1 tsp.)Weight in oz. U.S,Weight, metric
Active dry0.12.8 g.
Instant0.113.12 g.

Online sources say that 1 tsp. of instant is 3.1, 3.12 or 3.15 g.

I once measured SAF Instant Red, and thought 1 tsp. was 2.8 g. Instant yeast is hard to weigh. The problem is filling a true teaspoon – or even verifying that a teaspoon measures exactly 4.9 ml. It is necessary to weigh repeatedly with a verified teaspoon and average the readings. There may be some further variation depending on how the yeast has been processed and handled, and temperature. It may be ≧3.3 g. for other brands. I have decided to round up 3.1x, to 3.2 g. This is better starting point.

A sample conversion, active dry by volume to instant by volume and weight: 2.5 tsp. active dry yeast weighs over 7 grams. The equivalent amount of instant yeast using the ratio of 5 to 4, is 2 tsp. which weighs 6.4 grams. More conversions:

Old Active
Active DryActive DryActive DryInstantInstantInstant
tsptsp.US oz.Gramstsp.US oz.Grams
1 Tbsp.
1 packet, after 1999
3 (1 Tablespoon)
1 "old" packet
1 packet after 2015

Bread Machine

Instant dry yeasts , rapid/quick-rise yeasts, and bread machine yeasts vary in some ways but are equivalent for bread machines. Beth Hensperger suggested using bread machine yeast in bread machine recipes in the Robotic Kneads chapter of her Bread Bible. In another book, The Bread Lover’s Bread Machine Cookbook, Bread Hensperger suggested that SAF brand instant dry yeast was a more efficient yeast for bread machine baking, providing different amounts of yeast for instant dry yeast and bread machine yeast. This advice was not helpful.

I use instant dry yeast in my bread machine. I have had other issues with recipes from The Bread Lover’s Bread Machine Cookbook.

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