Onion and garlic notes in hoppy beer from certain hop varieties

What the note smells like

At low levels it reads as a savoury, slightly sulphury edge, a bit like chopped spring onion or chives. At higher levels it becomes raw onion, garlic or, for some tasters, sweat. In a dank West Coast IPA a whisper can blend with the resinous hop character. In a delicate pale ale it sticks out.

Drinkers sometimes describe it as dank, which muddies the water. Dank usually means resinous and herbal. Onion and garlic are a narrower, clearly savoury sulphur note. If you could imagine it in a curry base, it is onion.

Where it comes from

Hops contain hundreds of aroma compounds, including sulphur compounds that carry very strong smells at tiny concentrations. Some of these smell of tropical fruit and blackcurrant, as covered in our guide to catty notes in hoppy beer. Others smell of onion and garlic.

Brewers most often link onion and garlic notes with high alpha acid varieties from the Columbus, Tomahawk and Zeus family (often sold together as CTZ), Summit and Apollo. That does not mean every lot of those hops smells of onion. Many brewers and growers report that the character varies a great deal with growing region, season and harvest timing, with later harvested lots often more savoury. Treat the variety name as a warning to smell carefully, not a guarantee.

Why dry hopping shows it most

Hops added early in the boil lose most of their volatile oil, so sulphur compounds largely boil away. Late hops, whirlpool additions and above all dry hops keep their oils, including the savoury ones. That is why onion and garlic notes turn up mostly in heavily dry-hopped beers. A recipe that uses CTZ for bittering rarely smells of onion. The same hops at 8 to 10 grams per litre in the dry hop might.

Hop pellets that have been stored warm or exposed to air also change. Our guide to hop storage and freshness covers why cold, oxygen-free storage matters, which is a real issue in Indian heat.

How brewers screen hops before they brew

The simplest screen is the rub test. Crush a few pellets or cones between your palms, cup your hands and smell. Onion and garlic, if present, usually show straight away. A hop tea sensory test goes further: steep a measured amount of hops in hot water or in a neutral beer, let it cool and smell and taste the liquid. That shows what the hops will give in beer rather than in the hand.

Breweries buying hops at contract time often do this on samples from several lots of the same variety. If one lot smells of onion and the others do not, they choose the cleaner lot. Smaller brewers buying through distributors have less choice, but they can still smell before they brew and adjust the recipe.

Why two tasters disagree about it

Sulphur compounds are a classic case where people differ. One drinker finds a CTZ dry-hopped IPA pleasantly dank. The person next to them finds it smells of garlic bread. Both are telling the truth. Sensitivity to individual aroma compounds varies a lot from person to person and previous experience shapes the words people reach for.

For a brewery this matters at release. If the head brewer is not very sensitive to onion notes, a batch can pass in-house and draw complaints in the taproom. A small panel of three or four tasters, each asked to note savoury or sulphury aromas specifically, catches far more than one experienced nose. Asking the question directly helps too. People often notice onion only once someone has named it.

What to do if a batch already has it

Once the note is in the beer, it is hard to remove. Time helps a little, as some volatile sulphur compounds fade over weeks. Blending with a cleaner batch can dilute it. Most brewers learn the lesson on the next batch:

• Reduce or swap the offending variety in the dry hop.
• Move it to an earlier addition where more of the oil boils off.
• Pair it with fruity varieties that sit on top of the savoury note.
• Keep a record of which lot numbers caused trouble, so you know which to avoid next time.

Your first step

Next time you buy a hoppy beer, check the hop varieties on the label if they are listed. Rub a fresh spring onion between your fingers, smell it, then smell the beer. Knowing that one reference makes it much easier to spot the note early, whether you brew or just drink.

Common questions

Why does my IPA smell like onion?

Some hop varieties and crop lots carry sulphur compounds that smell of onion and garlic. They show up most in heavily dry-hopped beers.

Which hops are linked to onion and garlic notes?

Brewers most often mention Columbus, Tomahawk and Zeus (CTZ), Summit and Apollo, though the character varies by lot, region and harvest timing.

Can brewers remove onion notes from a finished beer?

Not easily. Some fades with time and blending can dilute it, but the usual fix is changing the hops on the next batch.

Is onion aroma the same as dank?

Not quite. Dank usually means resinous and herbal. Onion and garlic are a narrower, clearly savoury sulphur note.