Yeast production revolutionized baking
Did you know that in 1872, the first yeast factory was established at Maisons-Alfort, a suburb of Paris?
Baron Max von Springer was head of this first factory and transformed the world of baking forever. Springer produced yeast on a larger scale with controlled processes, enabling bakers to obtain greater regularity in their production and to offer a higher quality product to a greater number of people. (1)
The yeast manufacturer aims to produce many living cells. From the laboratory phase to industrial tanks, they promote the multiplication of cells in optimal conditions. It is the combination of selected yeast and specific industrial processes that make it possible to obtain high-performance products adapted to each user’s needs.
What are the various stages of yeast production?
Production begins in what is called the “strain bank,” where the different strains of yeast cells, which have been specifically selected for their unique fermenting abilities, are stored at -80 °C. This is where unique and pure strains are conserved.
An initial liquid culture is prepared in a tube. A few milligrams of yeast are transferred to a culture medium, and this is placed in an incubator at a favorable temperature. The fermentation process then requires a few days.
After this, the cells are successively transferred to larger environments as the number of cells grows. The purpose of these steps is to successively increase the biomass, specifically the quantity of the cells produced, to reach a specific quantity for commercial purposes.
Then a fermenter is “pitched” to obtain the first generation of yeast. This pitching process is done by seeding the cells with different nutrients, molasses (sugar), air, and water to achieve the desired quantity. The result is several tons of yeast generated in just a few days. This duplication process is called “budding.”
Fun Fact: By the thirty-fourth “budding” a single cell will have produced seventeen billion more! (2)
The yeast is then separated from the culture medium, which enables the cells to multiply thanks to the use of a centrifugal separator. This centrifugal separator spins very fast, causing the yeast to fall to the bottom and the culture medium to stay on the top. This allows it to be easily separated. The manufacturer is then left with a perfect yeast cream, which can be cooled and stored in chilled conditions at 4 °C to ensure that the cells are inactive.
At this stage, different forms of yeast can be produced, and the byproducts of the process can be recycled and valorized for other derived products (e.g., animal feed, fertilizers…).
What are the different forms of yeast that can be produced?
Once in the cream form, the yeast can be processed into a variety of different forms to be sold.
Liquid yeast can be prepared from the cream and sold without additional developments. In liquid form, it has a dry matter content of roughly 15%-16%. This liquid can be sold in three forms:
- “Kastalia” or refrigerated bags,
- A container of 0.1 to 1m3 in size,
- In 25-ton trucks (this is usually only sold to large bakeries).
Another form that can be made is fresh or compressed yeast. To produce this form, the cream is passed through a rotary filter, or vacuum filter, which is a machine that sucks away the liquid, making it possible to obtain a fine layer. This layer is then processed in a mixer, which compresses the yeast. Next, it is cut into cubes and packed. Fresh or compressed yeast is roughly 30%-32% dry matter.
Fun Fact: There are several billions of identical cells in a single cube of baker’s yeast! (3)
To obtain dry yeast or dehydrated yeast, the cream passes through a rotary filter for a second time and then goes into an extruder and a drying plant. Through this process, manufacturers can remove even more water from the layer. This leads to yeast with 95% dry matter.
Yeast production is all about creating the right conditions for fermentation and enabling the cells to multiply. These three types of yeast can be used in so many different products from bread to supplements. So next time you are in the store buying fresh yeast to bake your favorite bread or pizza dough you can think about this exciting process and remember all of the careful work that has gone into making a single cube of fresh yeast just for you!