Yeast refers to a broad group of single-celled fungi, but in food contexts it almost always means Saccharomyces cerevisiae — the species used in baking, brewing, and winemaking for thousands of years. Yeast cells consume sugars and produce carbon dioxide (which makes bread rise) and alcohol (which makes beer and wine).
Beyond its role in fermentation, yeast is also consumed directly. Nutritional yeast is a deactivated form sold as flakes or powder, valued for its savoury, cheese-like flavour and high B-vitamin content. Yeast extract — the soluble contents of yeast cells — is the basis of products like Vegemite and Marmite, deeply embedded in Australian food culture.
Yeast is one of the most studied organisms in biology and has been instrumental in advancing our understanding of genetics, cell biology, and fermentation science.
How it's produced
Commercial baker’s yeast is produced by growing selected strains of Saccharomyces cerevisiae in large fermentation tanks fed with molasses (a byproduct of sugar refining). The yeast multiplies rapidly under controlled conditions of temperature, pH, and oxygen. After fermentation, the yeast is separated from the growth medium by centrifugation, washed, and processed into fresh compressed yeast, active dry yeast, or instant yeast.
Nutritional yeast is produced similarly but is then deactivated by heat treatment, so it can no longer ferment. Yeast extract is made by breaking open yeast cells (autolysis) and separating the soluble cell contents from the cell walls. Wild yeast strains used in traditional fermentation are not produced commercially — they are naturally present in the environment and are cultivated through practices like maintaining sourdough starters.
What it costs the planet (per kilo)
≈ Estimated from its category — typical for mushrooms, not measured for this item yet. Sources & methods →
Keeping it
In the freezer: about 180 days.
In the fridge: about 120 days (after opening).
In the pantry: about 730 days (from date of purchase).
Advice from Cubud’s own keeping notes — how to keep it, not a measured number.
What comes from this
Your household's take
One thumb per person, shared with your household — it steers what the wider-web shelf and the swap chips offer you. Tap again to take it back.
✎ Spotted something wrong? Suggest a correction
Checking who you are...