What does yeast come from?

In this brief article, we will provide you with the question: “What does yeast come from?” and discuss the production of industrial yeast. We will also discuss if you can substitute fresh yeast with dry yeast and talk about the differences between baker’s yeast and raising agent/chemical yeast. 

What does yeast come from?

Yeast comes from eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The most common type is called Saccharomyces cerevisiae.

There is evidence that the Egyptians employed fermentation to help their bread rise and become lighter 2000 years before Christ. 

They used a portion of “old” dough mixed with new dough to make the dough rise. They did not realize it, but there were small living organisms there that created gas and caused the bread to rise: yeast.

The discovery of this unseen world occurred only in 1674 when a researcher was able to view these microbes using a microscope he created.

How does the production of industrial yeast occur?

The isolation of yeast is used in the manufacturing of yeast on a large scale. Saccharomyces cerevisiae, which means “sugar-eating fungus,” is the active ingredient in commercial yeast. Enzymes in their cells help convert the starch in bread into sugar, which can then be digested to allow them to live and grow.

The steps of commercial yeast manufacturing may change from one producer to another, but the fundamentals remain the same. It all starts in the lab, with a little amount of a selected and pure strain inserted in a closed bottle containing a sterile nutritional solution for development and reproduction.

This Saccharomyces cerevisiae cultivation grows rapidly at a steady temperature for 12 hours. It is then moved to a bigger flask with molasses solution and nutritional broth to continue growing. The transfer technique is continued until a large enough yeast culture is established to begin the process in bioreactors.

Up to this stage, yeasts were cultivated in the absence of air to promote the development of yeast cells to the detriment of competitors. Because anaerobic fermentation is useless for yeast development, successive phases are carried out using sterile air injection. 

With the start of aerobic fermentation and the constant addition of molasses and nutrient solution, yeast growth may reach up to 12 tons. Every 3 tons of seed yeast yields around 11 tons of baker’s yeast, and the process must be tightly regulated to guarantee that 40 to 50 tons of yeast are generated in approximately 10 days with the same quality as the starting strain.

The creamy substance will be the foundation for fresh, dry-activated, and instant yeast.

Can I substitute fresh yeast with dry yeast?

Yes, you can substitute fresh yeast with dry yeast. But it is important to highlight that fresh yeast is three times weaker than dry yeast. So, if a recipe calls for fresh yeast and you only have dry yeast on hand, use 1/3 (one-third) of the amount of dry yeast.

You must use 10 grams of dry yeast for every 30 grams of fresh yeast. 

Dry yeast is the yeast in granulated powder form. Its ingredients include yeasts and an emulsifier (sorbitan monostearate). 

It does not need to be refrigerated because it is dry, and it may survive up to 6 months on average.

Fresh yeast has a substantially shorter shelf life than dry yeast. As a result, you may buy in bigger amounts and store them. It also does not require refrigeration and produces far more than fresh yeast. 

What is the difference between baker’s yeast and raising agent/chemical yeast?

Baker’s yeast is made out of living microscopic fungus while raising agent/chemical yeast is produced of sodium bicarbonate and acids. They behave in quite different ways. 

The living yeast fungus feeds on the glucose in the wheat flour, and their digestion creates, among other things, the carbon dioxide bubbles that cause the dough to rise. 

The same gas is produced in chemical yeast by interactions of potassium bicarbonate with some acid. 

Bicarbonate is combined with chemicals that turn acidic when they come into contact with liquids or are heated in the production of baking powder. 

Other FAQs about Yeast that you may be interested in.

What happens to yeast in hot water?

How to counteract too much yeast in your body?

Can nutritional yeast go bad in the fridge?

How much is ¾ tsp yeast in grams?


In this brief article, we provided you with the question: “What does yeast come from?” and discussed how the production of industrial yeast occurs. We also discussed if you can substitute fresh yeast with dry yeast and talked about the differences between baker’s yeast and raising agent/chemical yeast. 


“Painel.” Accessed January 12, 2022. http://www2.club-paneo.com/gb_en/faq-detail-6.html.

Massa Madre Blog. “Sobre o fermento biológico,” August 30, 2018. https://massamadreblog.com.br/know-how/info-tecnicas/fermento-biologico/.

“Yeast.” In Wikipedia, January 12, 2022. https://en.wikipedia.org/w/index.php?title=Yeast&oldid=1065172520.

Comidinhas do Chef. “Como Substituir o Fermento Biológico SECO X FRESCO,” April 9, 2020. https://comidinhasdochef.com/como-substituir-o-fermento-biologico-seco-x-fresco/.