Sour beer confuses more first-timers on the Beer Mile than almost anything else we pour. People assume it's a mistake — beer isn't meant to taste like that, surely? — until they try a well-made gose on a hot afternoon and get it immediately. This is our beginner's guide to sour beer: what actually makes it sour, the difference between the main styles, and where to find one on a guided taproom day.
So what actually makes beer sour?
Ordinary beer — a lager, a pale ale, an IPA — is fermented by a single, carefully chosen brewer's yeast that converts sugar into alcohol and produces clean, predictable flavours. Sour beer introduces a different cast of microbes into that process, deliberately, and lets them do some of the work instead.
The two main culprits are:
- Lactobacillus — a lactic acid bacteria, the same family used in yoghurt and sourdough, which produces a clean, tart, lemony sourness.
- Brettanomyces ("Brett") — a wild yeast that produces more complex, sometimes funky or barnyard-like flavours over long ageing, alongside some acidity of its own.
Brewed carefully, the result isn't a flaw — it's a whole extra flavour dimension that clean beer doesn't have. It's worth saying clearly: a proper sour beer is not the same thing as a beer that has gone off. An infected or oxidised pint tastes flat, cardboardy and unpleasant in an uncontrolled way. A genuine sour is a deliberate, balanced style, brewed on purpose, the same way a winemaker deliberately makes a dry wine rather than a sweet one.
The main sour beer styles, explained
Gose
Pronounced "goh-zuh", this is a German wheat beer style originally from Goslar, brewed with a pinch of salt and often coriander, then soured to a light, refreshing tartness. Modern breweries frequently add fruit — raspberry, passionfruit, mango — to gose, making it one of the most approachable entry points into sour beer. Low in bitterness and usually low-to-medium in ABV, it's a genuinely easy style to start with.
Berliner Weisse
A close cousin of gose, without the salt — a pale, low-ABV, sharply tart wheat beer that was traditionally served in Berlin with a shot of fruit syrup to soften the acidity. Modern versions are often fruited by the brewer instead, in the same vein as a contemporary gose.
Lambic
The deep end of the sour pool. Lambic is a traditional Belgian style, spontaneously fermented by whatever wild yeast happens to be floating in the air of the brewery, then aged in wooden barrels for one to three years. The result is dry, funky, complex and often quite different from batch to batch — closer in spirit to a natural wine than to a typical pint. Fruited versions (kriek with cherries, framboise with raspberries) are the more widely available way in.
Kettle sour
Not a style so much as a modern technique, and the reason sour beer has become so much more common in the last decade. Instead of waiting months or years for wild fermentation, brewers add a lactic acid culture to the wort in the kettle before boiling, let it sour for a day or two under controlled conditions, then boil as normal and ferment with regular yeast. It's how most modern gose, quick sours and fruited "sour pale" styles are made — fast, consistent and a much lower-risk process for a small brewery than a true barrel-aged lambic.
Kettle souring vs traditional souring
The practical difference matters if you're choosing what to order. Kettle-soured beers (most gose, most modern fruited sours) tend to be bright, clean and immediately tart, usually low-to-medium ABV, and ready to drink within weeks of brewing — a safe, approachable choice. Barrel-aged, spontaneously fermented beers (true lambic and its relatives) take far longer, cost more to produce, and reward a slower sip: expect more funk, more complexity and less predictability from bottle to bottle. Neither is "better" — they're different tools for different afternoons.
What does sour beer actually taste like?
Think somewhere between a crisp white wine, a squeeze of lemon and a wheat beer. The acidity hits first, followed by fruit character if it's been added, then a dry, clean finish — sour beer is rarely sweet, even the fruited versions. If you enjoy cider, kombucha or a properly tart lemonade, you already have the palate for it. It's also a genuinely refreshing style on a warm day, which is why gose in particular has become a taproom summer favourite.
New to sours? How to try your first one
- Start with a fruited gose. It's the most forgiving entry point — light, refreshing and rarely aggressively sour.
- Ask before you order. Taproom staff will happily tell you how sharp a beer is before you commit a full pour.
- Try it alongside something clean. Tasting a sour next to a lager or a standard ale makes the contrast — and the appeal — much clearer.
- Don't judge the whole category on one beer. Gose and lambic are genuinely different experiences; disliking one says nothing about the other.
Where to try sour beer on the Bermondsey Beer Mile
Several of the independent taprooms along the Beer Mile brew or rotate sour and fruited beers alongside their core range of pales, IPAs and lagers, particularly through spring and summer — availability changes taproom by taproom and week by week, so it's always worth asking what's currently pouring rather than assuming. On our guided Bermondsey Beer Tasting Tour (£49pp, 2–3.5 hours, tastings included at every stop), your guide knows which of the four taprooms has something sour on that day and can point you towards it, alongside the more familiar styles covered in our guide to what actually counts as craft beer. We meet at Southwark Brewing Co, 46 Druid Street, and run tours for private groups of 6 to 60+ as well as our regular public dates — see private & group tours for details.
If sours aren't quite your thing on the day, the Mile has plenty of range either way — our roundup of the best IPAs to drink in London right now covers the hoppier end of the spectrum, and the Ultimate Beer Mile Guide has a section on every brewery so you can see the full range before you go.
Sour beer and food
Acidity is a brilliant palate-cleanser, which makes sour beer an underrated food pairing. It cuts through rich, fatty or salty dishes particularly well — soft, rinded cheese, charcuterie, oysters, fried food, or anything finished with citrus or vinegar. It's the same logic as pairing a crisp white wine with the same dishes, and a fruited sour works especially well alongside something sharp like goat's cheese.
Good to know before you order one
- ABV varies widely. Kettle-soured gose is often a sessionable 3.5–4.5%; some barrel-aged sours run stronger, so check before you commit to a few rounds.
- Cloudy is normal. Fruited sours are often hazy with fruit solids — that's expected, not a fault.
- Prices can be higher. Barrel-aged and long-conditioned sours cost more to brew than a standard pale, and taprooms price accordingly.
- It's a small-batch category. Sour beers rotate faster than a brewery's core range, so if you find one you love, don't assume it'll still be pouring next month.
Fancy trying one for yourself?
The easiest way to taste your way across several sour, hoppy and classic styles in one afternoon is a guided crawl — our Bermondsey Beer Tasting Tour visits four independent taprooms with a beer at every stop, and a guide who'll steer you towards whatever's interesting that day, sour or otherwise. It also makes a genuinely good present for a curious drinker: our gift vouchers are delivered instantly by email and never expire.