Can you freeze yeast?

In this article, we will answer the question “Can you freeze yeast?”, and how to freeze yeast?

Can you freeze yeast?

Yes, you can freeze yeast. Freezing helps to extend the shelf-life of the yeast up to 6 months, more on this topic in the article below.

The expansion of the global yeast industry is forecast to reach 4.4% p.a. in the coming years. Between 2008 and 2014 the market increased with an average annual growth of 8.0%. Currently, active yeasts account for 70.2% of the global demand while inactive yeasts have a 29.8% share of the market (1).

All you need to know about yeast 

Yeast is used as a leavening agent in baking. It is also used to fluff up muffins, pretzels, rolls, bagels, biscuits, and even pancakes. Besides leavening the dough, yeast also adds a lot of flavor to the finished product. 

Yeasts are typically spherical, oval or cylindrical in shape and a single cell of Saccharomyces Cerevisiae (a mold which ferments the sugar in cereal) is around 8 μm in diameter. Every cell has a double-layered wall, which is porous to certain substances and in this way food fabric is taken into the cell and metabolites leave it (3).

Baker’s yeast, nutritional yeast, brewer’s yeast, and distiller’s yeast are the most commonly used. The baker’s yeast is further divided into categories: fresh yeast, active dry yeast, instant yeast, or rapid-rise yeast.

These strains of S. cerevisiae are employed in three main industrial processes: the production of alcoholic beverages such as wine, beer, sake, potable spirits, and to a large extent, industrial alcohol; the baking industry, although specific strains are used to meet the needs of baking; and the production of biomass, extracts, and flavor compounds. The yeast used in such processes can be either primary grown or spent yeast from the brewing and distilling industries (2).

Fresh yeast 

The filtered and dried yeast can alternatively be used to make cake yeast. Cake yeast is another form of compressed yeast and can be categorized as active dry yeast. It differs from granular yeast in that rather than granulation, the dried yeast is extruded or cut into blocks/cakes (3).

Fresh yeast, also referred to as compressed yeast or cake yeast, is the first choice of professional bakers and cooks. 

Fresh yeast comes in the form of a pale block that has a soft and crumbly texture. It has a thicker texture and a stronger taste than instant yeast. It may not be as readily available as instant yeast. 

Active dry yeast 

Active dry yeast is commonly used by home bakers. It has to be dissolved in water to be activated before mixing in with the dough. Active dry yeast takes double the time it takes for the instant yeast for dough proofing. Active dry yeast should be rehydrated in warm (35°~40°C) water before addition to the dough. This process minimizes leaching of reducing compounds from the yeast into the rehydration water (reduced glutathione, GSH) as well as minimizing loss in fermenting activity. Such reducing compounds produce slacker, more extensible and more relaxed doughs (2).

Instant yeast or rapid-rise yeast

Granular yeast, also known as instant dried yeast, is a form of compressed yeast. Stored cream/liquid yeast is passed through a filter, usually a filter press or rotary vacuum filter, which removes water increasing its solids content to approximately 30 %. The filtered yeast is then dried using fluid-bed dryers. As the yeast is dry it generally does not require refrigeration as the low water content reduces the risk of microbial contamination (3).

As the name suggests, instant yeast is quick to act and raises your dough in a matter of a few minutes, 30 minutes tops. It is also referred to as the bread machine yeast. Instant yeast has a higher potency and does not need to be dissolved in water for activation. You can mix it directly with the dry ingredients.

How to keep the yeast alive?

To keep the yeats alive, it needs to be constantly refrigerated right after opening its packet. All types of dry yeast can be refrigerated or frozen. 

Let the frozen yeast come to room temperature before you add it to your dough. Active or instant yeast can be refrigerated for up to 4 months. Freezing extends its shelf-life for up to 6 months.  Active dry yeast loses some activity upon storage when exposed to the oxygen of the air. For storage under nitrogen, or when vacuum packed, the loss is about 1 % per month and generally less than 10% per year (2). Dry yeasts have a shelf life of about 1 (active dry yeast) or 2 years (instant active dry yeast) when packed under vacuum or nitrogen (4).

How to freeze yeast?

If unopened, dry yeast can be safely stored in a cool and dark pantry or a kitchen cabinet. Keep it away from the sources of heat like direct sunlight or the stovetop. Do not let it anywhere near moisture.

Once opened, you need to ensure that the yeast is tightly sealed. Then you need to refrigerate or freeze the yeast. If the original packaging is not sufficient to ensure a tight seal, package the yeast using a freezer bag.

Sometimes, the yeast may live beyond the 4-6 months time window. It may also go bad sooner than this estimated time. Therefore, it is always a wise idea to test the yeast for proofing before you mix it with your dough.

How to proof dry yeast?

Inactive yeast is not a problem. Since it can be easily activated and checked for its potency by using the following proofing method.

  1. Stir in 1 tsp of sugar and 2 ¼ tsp of yeast into ¼ cup of warm water. 
  2. Let it sit for about 10 minutes.
  3. After 10-15 minutes, if the mixture gives off a yeasty smell and becomes foamy or bubbly, it is potent and ready for baking.

Can you freeze fresh yeast?

Fresh yeast is moist and needs to be wrapped in multiple protective layers for complete preservation. Start by wrapping the block of fresh yeast first with a plastic sheet and then wrap with foil. Wrap again with a plastic sheet. 

Put the wrapped fresh yeast inside a freezer bag. Squeeze out as much air as possible from the bag before you seal it. Put a clear label on the bag.

The label will help in identifying the frozen yeast and keep track of its shelf-life. Identify the coldest spot in your freezer to store the yeast. Use the frozen fresh yeast within 6 months of storage. Yeast can be frozen and thawed without loss of fermenting activity or with only minimal losses. It can also be stored as frozen compressed yeast for weeks without such loss (2).

However, long storage periods negatively affect the properties of the yeast. Studies showed that freezing and frozen storage of compressed yeast at –18°C for up to 90 days produced an increase of dead cells and caused losses of CO2 production; baking quality reflected the lower specific loaf volume and longer proof times. As the length of frozen storage of the compressed yeast increased, the amount of both dead cells and reducing substances leached from the yeast cells increased (5).

How to use frozen dry yeast?

Let the yeast, instant or dry, sit on the counter for 30-60 minutes and let it come to room temperature. This step is important to let the yeast perform up to its full potential. 

How to defrost fresh yeast?

Depending upon the volume of the block of fresh yeast, it may take anywhere from 12-24 hours to defrost. Leave the block in the fridge overnight to let it thaw slowly. 

Ideally, you should allow the thawed fresh yeast to reach room temperature before you use it for baking. However, you can skip this step if you are pressed for time. 

Other FAQs about Yeast that you may be interested in.

Can you eat yeast raw?

Does Nutritional Yeast Have MSG

What is the best temperature for yeast?

Conclusion

In this article, we answered the question “Can you freeze yeast?”, and how to freeze yeast?

References

  1. Saif, Said. Yeast Congress 2020-Market analysis. Oxid Antioxid Med Sci, 2021, 10, 2.
  2. Reed, G., Nagodawithana, T.W. 1991. Baker’s Yeast Production. In: Yeast Technology. Springer, Dordrecht. 
  3. Ali, Akbar, et al. Yeast, its types and role in fermentation during bread making process-A. Pakistan J Food Sci, 2012, 22, 171-179.  
  4. Hidalgo, A., and A. Brandolini. Bread—Bread from Wheat Flour. Encyclopedia of Food Microbiology; Batt, CA, Tortorello, ML, Eds. 2014, 303-308.
  5. Ribotta, Pablo D., Alberto E. León, and María Cristina Añón. Effects of yeast freezing in frozen dough. Cereal Chem, 2003, 80, 454-458.