Beer tastes or smells like cooked corn, creamed corn or canned vegetables
mediumDMS (dimethyl sulphide) is produced by the thermal breakdown of S-methylmethionine during malting and brewing. Long, vigorous, lid-off boils drive it off; short or covered boils trap it.
Likely causes
| Cause | Process article | Ingredient | Notes |
|---|---|---|---|
| Boil too short for a Pilsner-malt-heavy grist | The boil — bitterness, sterilisation, and DMS | Weyermann Pilsner Malt | Use a 90-minute boil for grists with >50% Continental Pilsner malt. |
| Boiled with the lid on | The boil — bitterness, sterilisation, and DMS | — | DMS volatiles condense on the lid and drip back into the wort. Always boil lid-off. |
| Wort cooled too slowly | The boil — bitterness, sterilisation, and DMS | — | DMS continues to form between flame-out and ~70 °C. Get below 70 °C in <20 minutes if possible. |
When DMS shows up most
| Beer type | DMS risk |
|---|---|
| All-Pilsner-malt lager or Pilsner | Very high |
| Helles or Vienna with Munich malt | Moderate |
| British or American ales (pale ale malt base) | Low |
| Heavily roasted beers (stouts, porters) | Negligible |
Threshold and perception
The flavour threshold for DMS in beer is about 30-50 ppb. Below that, it sits below conscious perception but can lend a “fresh-corn” sweetness — actually pleasant in moderation in light lagers. Above 100 ppb it’s distinctly off.
Recovery
A finished beer with noticeable DMS can’t really be saved. Plan to prevent rather than rescue.
For your next Pilsner: 90-minute open boil, immersion chiller (or counter-flow) to get below 70 °C within 20 minutes of flame-out.
Related learn articles
- The boil — bitterness, sterilisation, and DMSWhat the boil does, why 60 minutes (or 90 for Pilsner malt), and how to manage evaporation and DMS.
- Off-flavours — what they are and where they come fromA quick reference for the most common off-flavours in homebrew, what they taste like, and what causes them.