Does active dry yeast expire?

In this brief guide, we are going to answer the question “does active dry yeast expire” with an in-depth analysis of whether or not active dry yeast expires. Moreover, we are going to discuss the shelf life of active dry yeast along with the uses of yeast.

According to research, the global yeast market was valued at around USD 3,230 million in the year of 2016 and it is expected to reach approximately USD 5,417 million by 2022. This market is expected to exhibit a compound annual growth rate, CAGR of around 9% between 2017 until 2022. From the year of 2016, the global yeast market will increase steadily until 2022 (1).

So without much ado, let’s dive in and figure out more about it.

Does active dry yeast expire?

Yes, like all other food items there is a certain time when active dry yeast expires. What we mean by the expiration of yeast is that it longer will be able to carry out its leavening function and it won’t be able to froth which is an indication that active dry yeast has lost its potency.

Drying yeast biomass enhances shelf life of food products. In the case of probiotic yeast biomass, the freeze-drying process is usually applied, since this type of drying saves the living cells. The moisture content of food powders is usually between 2% and 8%. At this level, powders are stable with an average shelf life of 12–24 months (2). Instant active dry yeast has a shelf life of about 2 years when packed under vacuum or nitrogen (5). Store it in a cool, dry place, away from direct sunlight. 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 (4).

Therefore you can store it in a cool and dry corner of your pantry or kitchen cabinet.

On the other hand, once the package of yeast is opened, its shelf life also decreases. 

Thus, open active dry yeast lasts for about 4 months in the fridge when kept at or below 40 degrees Fahrenheit in an air-tight container or plastic zipper bag. 

Once you have opened the package of the active dry yeast it is best to store it in a plastic zipper bag or an air-tight container so that no moisture will find its way to the yeast. Active dry yeast loses some activity upon storage when exposed to the oxygen of the air.

It is worth mentioning that the sunlight, oxygen, and moisture can degrade the quality of the active dry yeast and can also shorten its shelf life therefore care should be taken while handling and storing active dry yeast. In general, higher temperatures of storage, along with exposure to moisture, oxygen and light enhances chemical changes such as lipid oxidation, caking and browning, which limits the shelf life and leads to nutrient loss of powdered food products (3).

You should always remember that you should not use a wet spoon to scoop out the dry yeast. Moreover, close the lid of the jar as soon as you scoop out the dry yeast so that the moisture won’t find its way into your active dry yeast and spoil it.

There must be written the “best by” or “best before date” written on the package of active dry yeast, but you should always keep one thing in mind that the “best before” or the “best by” dates are mainly focused on the quality rather than the safety. 

Thus you will get the best quality of the yeast within the “best by” or “best before date” but you can still use the unopened, properly stored dry yeast even after some time from this date (6).

Other FAQs about Yeast which you may be interested in.

How many tablespoons are in a packet of yeast?

Can I store active dry yeast in the freezer?

Yes, you can store active dry yeast in the freezer but care should be taken in this regard. The yeast lasts for about 6 months in the freezer if stored properly. 

According to studies, most fungal cultures frozen at -20° to -80°C in mechanical freezers remain viable. Overall failure rate for mitosporic ascomycetes, Zygomycetes, and yeasts after 5 years in storage at -20°C was 5.1% (7). However, a study showed that the loss in activity upon frozen storage is of about 10% a year for active dry yeast (4).

Care should be taken while storing yeast in the freezer, you should always store the yeast in plastic freezer bags or an air-tight container to preserve its freshness for a long time.

Thus storing the yeast properly in the freezer will increase its shelf life considerably owing to the cool temperature of the freezer that halts the bacterial growth on the yeast.

What are the uses of yeast?

Yeast is used as a leavening agent for a long time. 

Both fresh and dry variants of the yeast are used in a variety of doughs, bread, and even in the production of beer. Yeast is a biological leavening agent and feeds on the sugar present in the solution. Then it liberates out carbon dioxide that is responsible for making the fluffy buns. That is the very reason that it is advised to firstly add the yeast in a bowl of warm water containing sugar so that the yeast can activate.

Baker’s yeast produces the CO2 that results in dough leavening and contributes to the flavor and crumb structure of bread. Baker’s yeast is a biotype of S. cerevisiae that can metabolize sugars both aerobically, producing the end products carbon dioxide and water, and anaerobically, producing ethanol and carbon dioxide (1).

The commercially available yeast is present in its dormant state so that it does not react while it is in its packaging. 

To activate the yeast, it has to be first added in warm water with sugar, honey, or fructose syrup added in it.

How can I check the potency of active dry yeast?

So what you can do to check the potency of the dry yeast is to take ¼ cup of warm water and add 1 tsp of sugar to it. Afterward, add 2¼  tsp of dry yeast to it or you can add an envelope of yeast to it. Let it stand for approximately 10 minutes.

 If you see the foam formation in the water after 10 minutes, then it is an indication that active dry yeast is still potent and you can use it.

Conclusion

In this brief guide, we answered the question “does active dry yeast expire” with an in-depth analysis of whether or not active dry yeast expires. Moreover, we discussed the shelf life of active dry yeast along with the uses of yeast.

Citations

1. Yusof, Abdul Halim, et al. Potential application of pineapple waste as a fermentation substrate in yeast production. Int. J. Sci. Technol. Res, 2020, 9, 1933-1937. 
2. Jach, Monika E., and Anna Serefko. Nutritional yeast biomass: characterization and application. Diet, microbiome and health. Academic Press, 2018. 237-270.   
3. Tehrany, Elmira Arab, and Kees Sonneveld. Packaging and the shelf life of milk powders. Food packaging and shelf life, a practical guide. CRC Press, Boca Raton, London, 2010, 127-141.  
4. Reed, G., Nagodawithana, T.W. 1991. Baker’s Yeast Production. In: Yeast Technology. Springer, Dordrecht. 
5. Hidalgo, A., and A. Brandolini. Bread—Bread from Wheat Flour. Encyclopedia of Food Microbiology; Batt, CA, Tortorello, ML, Eds. 2014, 303-308.
6. Gravely, M. Before You Toss Food, Wait. Check It Out! Food Safety and Inspection Service. USDA. 2022.
7. Nakasone, Karen K., Stephen W. Peterson, and Shung-Chang Jong. Preservation and distribution of fungal cultures. Biodiversity of fungi: inventory and monitoring methods. Amsterdam: Elsevier Academic Press, 2004, 37-47.