Yeast Extract: Brewer's Yeast and the Alcohol Question

Some yeast extract is made from spent brewing yeast, which raises an obvious question. The answer turns on what 'spent' means and on a principle that applies well beyond this ingredient.

Yeast extract is the savoury backbone of stock cubes, gravy granules, crisps, soups, sauces and the entire category of products that need to taste of something without containing much. It is also what Marmite and Vegemite essentially are.

The question it raises is specific and reasonable: some of it is a by-product of brewing beer.

What it is

Yeast extract is what you get when yeast cells are broken open and their contents collected. The cell walls are separated out, leaving a concentrated paste or powder rich in amino acids — including glutamate, which is why it tastes savoury and why it is used as a natural alternative to MSG.

The breaking open is done by autolysis — letting the yeast's own enzymes digest it — or by adding enzymes, or mechanically. Hence 'autolysed yeast extract' on labels.

The two yeast streams

1. Primary-grown yeast. Grown deliberately on molasses or another sugar substrate for the purpose of making yeast extract. Never near an alcoholic process. This is the dominant source for food-grade yeast extract today, and it is what most large manufacturers use.
2. Brewer's yeast. The spent yeast left after beer fermentation, historically collected and sold on rather than discarded. This is the source that gives rise to the question, and it is the traditional basis of Marmite specifically, which began as a way of using brewery waste.

The alcohol question, properly

Spent brewer's yeast is separated from the beer, washed, and processed. It is the organism, not the drink. But it has been in contact with alcohol, and residual amounts can be present before processing.

Scholarly views split along a line that will be familiar from several other pages here:

• The more permissive position holds that the yeast is a separate substance from the beer, that washing and processing remove residual alcohol, and that any trace remaining is far below an intoxicating level and does not carry the ruling. Istihalah and the treatment of trace residues both support this.
• The cautious position holds that a by-product of alcohol production is connected to a prohibited process in a way that matters independently of the final chemistry, and prefers yeast extract from primary-grown yeast.

What you can tell from a label

Less than you would like, which is the recurring shape of this subject:

• 'Yeast extract' or 'autolysed yeast extract' — does not state which stream. Most commercial supply is primary-grown, but the label does not say.
• 'Brewer's yeast' — names itself. Sold as a supplement in its own right, for B vitamins and chromium.
• 'Nutritional yeast' — primary-grown, deactivated, never a brewing by-product. The savoury flakes sold for vegan cooking. Straightforward.
• 'Baker's yeast' — primary-grown for baking. Straightforward.
• 'Torula yeast' — a different species, grown on wood sugars or molasses. Used as a savoury flavouring. No brewing connection.
• Halal certification — resolves it, because the certifier has established which stream the supplier uses.

Bread, and why it is not the same question

Yeast in bread produces small amounts of ethanol as it raises the dough, and almost all of it evaporates during baking. This is sometimes raised as a parallel question and it is not really one: the ethanol is incidental, the product is not an intoxicant, the quantity cannot intoxicate, and bread has never been in dispute. The same reasoning applies to naturally fermented foods such as kefir and some pickles that carry trace ethanol.

What else is in the packet

Yeast extract lives in stock cubes and seasoning blends, where the things worth reading are elsewhere:

• Meat extract, chicken fat, beef fat — slaughter questions, and the real issue in most stock products.
• Disodium inosinate (E631) — can be animal or fish derived, unstated.
• Mono- and diglycerides, and unqualified fats — source unstated.
• Flavourings — the usual carrier question.

A vegetable stock cube is a much simpler object than a chicken one, and the yeast extract in it is rarely the hardest part of either.

How we treat it

Yeast extract does not trigger a hold. Products naming brewer's yeast specifically move into review, so that readers holding the cautious position can see it rather than having it decided for them. Meat extracts and unspecified animal fats in the same product are what actually stop it.