Sour beer for beginners

Where the sourness comes from

Most beer is fermented with brewer's yeast alone, which turns sugar into alcohol and carbon dioxide. Sour beer adds bacteria, chiefly Lactobacillus and Pediococcus, which turn some of that sugar into lactic acid. It is the same acid that gives yoghurt and curd their tang.

Many sours also involve wild yeast called Brettanomyces, which adds earthy, funky or fruity notes over months of ageing. A typical sour beer finishes at a pH of around 3.2 to 3.6, against roughly 4.0 to 4.5 for most beers. That gap is the sharpness you taste.

Fast sours and slow sours

There are two broad ways to make a sour beer.

Kettle souring is quick. The brewer sours the wort with Lactobacillus for a day or two, then boils it to kill the bacteria before fermenting it normally with yeast. The result is clean and bright, with a lemony tartness. Most fruited sours on taproom menus are made this way.

Mixed fermentation is slow. Yeast, bacteria and often Brettanomyces work together for months or years, frequently in oak barrels. These beers are more complex, with layers of funk, fruit and acidity. They also take up space and patience, which is why they cost more.

Brewers keep sour work well away from the rest of the brewery. Lactobacillus and Brettanomyces that escape into the clean side can sour a whole run of lagers, so many breweries keep separate hoses, gaskets and even tanks for their sour programme.

The styles to know

Berliner weisse is a light, pale wheat beer from Berlin, usually around 3 to 3.8% ABV, crisp and refreshing. It is the gentlest place to start.

Gose comes from Leipzig and is brewed with salt and coriander. It is tart, slightly salty and very easy to drink. Indian drinkers often find it familiar, because it echoes the salty-sour balance of a nimbu soda or a chaas.

Lambic and gueuze from Belgium are spontaneously fermented by microbes from the air, then aged for years. Gueuze blends young and old lambic into something dry, sparkling and complex. Flanders red is another Belgian style, aged in oak, with cherry, vinegar and wine-like notes.

Which to try first

Start with a fruited kettle sour or a gose. The fruit softens the acidity and gives you something familiar to hold on to. Mango, passion fruit and berries are common. Indian fruit such as jamun or kokum suits the style well too.

Once you enjoy those, try a plain Berliner weisse to taste the sourness on its own. Save lambic, gueuze and Flanders red for later. They are among the most rewarding beers in the world, but they make far more sense once your palate has adjusted to acidity.

Serve sours cold, around 4 to 8 °C, in a tulip or wine glass. Small pours are a good idea at first. Acidity can be tiring in large volumes until you are used to it.

Good sour or gone off?

This is the question beginners worry about. It is a fair one. A deliberate sour should taste clean and intentional: bright acidity, balanced by fruit, malt or funk, with a pleasant finish.

Signs of a fault include a strong vinegar smell in a beer that is not meant to have it, nail varnish or solvent notes, or a sourness in a beer that should not be sour at all. An IPA or lager that tastes tart has usually been infected. Our guide on sour infection off flavours explains how that happens.

Telling deliberate acidity from infection takes practice. Brewers train on reference samples so they can name lactic, acetic and other acids. The gap between a pleasant tang and a fault becomes clear once you have tasted both deliberately.

Sours with food

Acidity cuts through fat and richness, so sours work beautifully with food. Try a gose with fried fish or pakoras, a fruited sour with a fruit chaat, or a Flanders red with a rich meat dish. They are also excellent with cheese.

Sour beer rewards curiosity. Order a small glass, taste it twice and give it a fair chance before deciding. Many people who dismiss sours on the first sip end up loving them by the third.