Fault
Excess sulphur
Sulphur compounds from fermentation — normal and transient in young lager, a fault when they persist.
Also called rotten egg, struck match, sulphury.
What it tastes and smells like
Responsible compound: hydrogen sulphide and sulphur dioxide.
Where it may be expected
A faint struck-match note is within style for some fresh German and Czech lagers, and the historical "Burton snatch" was a sulphury note regarded as a mark of authenticity. Rotten egg or drains is a fault anywhere.
Intensity and context decide. In the styles below a restrained version of this can be part of the character; the same character running past that is still a fault there.
If you are drinking it
A faint struck-match note in a fresh lager is often within style. A strong rotten-egg or drain smell is a fault. Neither is harmful.
Not a safety issue. Beer’s alcohol, hop compounds and low pH make it inhospitable to organisms that cause illness.
What causes it
| Cause | Stage | How often | Who can act |
|---|---|---|---|
| Normal lager fermentation produces hydrogen sulphide, which escapes with the CO₂ and clears during lagering. Young, unlagered beer smells of it. | fermentation | most common | brewer |
| Nutrient deficiency — particularly zinc or free amino nitrogen — forces yeast into sulphur production. Underpitching has the same effect. | fermentation | common | brewer |
| Yeast left too long on the trub breaking down and releasing sulphury, meaty compounds. | conditioning | occasional | brewer |
If you are brewing it
- Brewer: Lager the beer for long enough. Sulphur clears with time and CO₂ evolution; rushing conditioning traps it. (prevents)
- Brewer: Pitch adequate healthy yeast, oxygenate wort properly, and supplement nutrients where the grist is adjunct-heavy. (prevents)
Where in the process this comes from
Steps that can produce this fault when they go wrong. Each links to what the step is for and how it is controlled.
- Bottom fermentation — Ferment cool with Saccharomyces pastorianus, suppressing yeast-derived fruit and spice so malt and hop character stand exposed.
- Lagering — Store beer cold for an extended period after fermentation to clarify it and produce the clean, rounded character lagers are named for.
- Sour mashing — Acidify wort by holding the mash warm and letting lactic bacteria already present on the grain work before the boil.
Often confused with
- Lightstrike — skunk, burnt rubber
- Yeast autolysis — rubber, burnt rubber
Evidence
What BeerHQ knows about this, and how. Every statement carries the state of the evidence behind it rather than being presented flatly as fact.
Sulphur compounds are produced in quantity during cold lager fermentation and are normal at that stage, dissipating during lagering; their presence in a young lager is expected rather than defective.
Backed by a source
Sources: Yeast: The Practical Guide to Beer Fermentation — print; Technology Brewing and Malting — print