Welcome to The Certified Beer Nerd with Nigel Ayling — your guide to the geeky side of beer.

Today’s off-flavour is DMS, or Dimethyl Sulfide. This one is often described as smelling like cooked corn, creamed corn, or even cooked cabbage. In higher concentrations, it can lean into vegetal or tomato juice notes, which aren’t exactly refreshing in a pint.

So how does it get there? DMS comes from a compound found in pale malts, especially pilsner malt. During the boil, it normally evaporates off in the steam. But if the boil isn’t vigorous enough, if the kettle is covered, or if the wort cools too slowly, DMS can hang around. Bacterial contamination can also create DMS, which is why it sometimes shows up in infected beers.

Now, like diacetyl, not all DMS is automatically a dealbreaker. In very light lagers, especially American light lager, a faint sweet-corn note can be acceptable and even expected. But in most other styles — IPAs, stouts, Belgian ales — it’s definitely considered a flaw.

Training your palate to detect DMS means locking in that creamed-corn aroma. Sensory kits can help, but you can also practice by comparing spiked beer to canned corn or freshly boiled corn on the cob. Once you’ve made that connection, you’ll spot it instantly.

So if your lager smells like the inside of a corn can, you’ve just found yourself some DMS.

That’s The Certified Beer Nerd — levelling up your tasting skills, one sip at a time.