How baker's yeast is made
A factory grows yeast from a flask culture into tens of thousands of kilograms in a few days.
- stations
- 6
- things upstream
- 4
- raw sources
- 3
- steps from the ground
- 2
The short version
Baker's yeast, Saccharomyces cerevisiae, is grown in stages. A lab culture feeds a small fermenter, which seeds ever larger tanks. In the last tank, air and sugar are fed in carefully so the cells multiply instead of making alcohol. Centrifuges and filters then concentrate the cells into cream, cakes or dry granules.
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Culture a pure strain
A single selected strain grows in laboratory flasks for 2 to 4 days. Starting from one strain gives the same rise and flavor in every batch.
2 to 4 days
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Step up through small tanks
The culture moves into batch fermenters that run for 13 to 24 hours and then into larger intermediate tanks. Growth is fed gradually and aerated constantly. This stage makes more ethanol and other alcohols than the later ones.
Goes in -
Feed it molasses and air
The sugar for growth usually comes from cane or beet molasses, the sticky by-product of sugar making. In the last big tanks, called the trade fermenters, air is pumped in hard for up to 15 hours. Oxygen and sugar are metered so alcohol production is suppressed by up to 95 percent and the cells put their energy into multiplying.
up to 15 hours
Goes in -
Spin out the cream
Centrifuges separate the yeast cells from the liquid they grew in. The resulting suspension is cream yeast, the form that industrial bakeries pump straight into dough mixers.
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Filter and shape the blocks
A filter removes most of the remaining liquid, leaving a soft beige solid. It is extruded and cut into cakes or blocks of compressed yeast, which are highly perishable.
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Dry and pack
Some of the yeast is dried to active dry or instant granules and vacuum packed. Dry yeast travels long distances, while fresh yeast is mostly supplied from local factories.
Worth repeating
- In 1996, after six years of work, S. cerevisiae became the first eukaryote to have its entire genome sequenced.
- Yeast was grown in specialized vats in Great Britain from 1879, and centrifuges for concentrating it came around the turn of the century in the United States.
Back to the ground
Follow every input upstream and baker's yeast starts as these 3 raw sources.
Open the whole family tree
Where it goes next
Baker's yeast feeds 29 lines directly and reaches 348 things in total.
Further down the line
Keep walking
Sources
Cite this page: "How baker's yeast is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/yeast