Kefir or buttermilk?

What is buttermilk, exactly?

Originally, it was what was left in the churn once the cream had turned to butter. On farms, the cream was left to stand for a day or two before churning, so it soured a little on its own, and the thin, sharp liquid that ran off the butter was soured too. Nothing was wasted: it went into the scones, the griddle cakes and the pancakes, and a cold mug of it was drunk with a meal.

The buttermilk in the supermarket today is usually made differently: skimmed or low-fat milk soured with a starter culture in a dairy. It keeps the character of the old stuff, though. It is thin, almost watery, fresh and clean on the tongue, with very little fat, since the fat went off with the butter. Most people buy a carton when they want to bake and use the rest within the week. Hardly anyone makes it at home any more.

And what is kefir?

Milk you ferment at home with live kefir grains: 20 g of grains in 1 litre of whole milk, 24 hours at 20 to 25°C.

Inside the grains, bacteria and yeasts work together. The yeasts give kefir an aroma buttermilk does not have: a hint of bread dough, a whiff of cider and a gentle tingle on the tongue. Because you normally use whole milk, the fat stays in and the kefir is creamy. You strain the grains out and they go straight back into fresh milk, so a new jar is ready every day. The full method is in How to make milk kefir.

Taste, texture and use side by side

Why kefir works in scones and pancakes

Buttermilk scones and pancakes get much of their lift from bicarbonate, which gives off bubbles of gas the moment it meets something sour. Buttermilk has long been that sour ingredient in British baking, which is why the two go together like tea and a biscuit.

Kefir is just as sour, often a bit more. Swap it in and the bicarb fizzes in the same way, the dough or batter puffs up and you get the same light, tender crumb. The crumb tends to come out slightly softer and richer, thanks to the extra fat of the whole milk, and the flavour carries a gentle tang without tasting of kefir as such. Older kefir that has spent a few days in the fridge and turned sharper is ideal here.

How to swap buttermilk for kefir

In nearly every recipe, use the same quantity of kefir as buttermilk. The only thing to watch is texture, because kefir is thicker. Loosen it with a splash of milk or water, roughly three parts kefir to one part liquid, until it pours like buttermilk.

• Scones: kefir replaces buttermilk or milk one for one, with self-raising flour or plain flour and bicarb. Add it gradually and stop when the dough is soft and only just holds together. The scones come out tall and tender, with that slight sourness that is so good with clotted cream and jam, in whichever order your household insists on. Handle the dough as little as possible and do not twist the cutter.
• Pancakes: for Pancake Day or a Sunday morning, kefir gives thick, fluffy pancakes, the kind that stack, and drop scones love it too. For thin pancakes with lemon and sugar, swap only part of the milk for kefir.
• Cakes: kefir keeps a cake moist and light. A good example is the kefir apple cake, made with Bramley apples, where kefir does the job buttermilk usually does.
• Fried chicken: chicken thighs soaked overnight in buttermilk with salt, paprika and garlic are the secret behind crisp, juicy fried chicken. Kefir does the same job: it tenderises the meat gently, and the seasoned flour clings well to the thicker marinade. Let the excess drip off, dredge, then fry or bake as usual.

Going the other way works too: if a recipe calls for kefir and you only have buttermilk, use it in the same quantity. Just expect a lighter, less creamy result.

Can you make kefir that tastes more like buttermilk?

You can get quite close. Made with semi-skimmed milk, kefir comes out thinner and lighter, and if you strain it a little earlier it is less yeasty.

It is still kefir, with that typical aroma and tingle. But cold from the fridge, in a glass at lunchtime, it goes a long way towards a glass of buttermilk. What each kind of milk does to your kefir, from whole milk to UHT and goat's milk, is in The best milk for kefir. Keep your grains in good shape, though: give them whole milk again every so often so they keep growing.

The texture can be tuned in both directions. Left longer, kefir turns thick and almost creamy, moving away from buttermilk towards a drinking yoghurt. All the adjustments are in Milk kefir too thin or too thick.

For the curious: real buttermilk from your own butter

If the idea of the old churn appeals, kefir opens the door. Stir a few spoonfuls of kefir into a carton of cream, cover and leave it overnight at room temperature: the cream ripens and takes on a light tang, just as it used to on the farm. Chill it, then whip it with a mixer well past the whipped cream stage, until it suddenly splits into yellow lumps of butter and a thin liquid.

That liquid is your buttermilk, a direct descendant of the farmhouse kind. Gather the butter, rinse it under very cold water while pressing it, and salt it if you like. The buttermilk can be drunk cold or go straight into tomorrow's scones. An old habit, with an ingredient from your own jar.

Which should you choose?

If you like a thin, clean, sour glass with your lunch, buttermilk remains the classic. If you want something creamier with more character, that you control yourself and never have to remember to buy, kefir is well worth trying. Plenty of households end up making kefir every day and using it wherever the recipe says buttermilk. For a comparison with the other fixture of the breakfast table, read Kefir or yoghurt?

With live milk kefir grains from £14, you make your own kefir every day: 10 g for half a litre, 20 g for a litre. You will find everything about making and caring for it on the milk kefir page, and a spoonful of strained kefir cheese on a warm toasted crumpet is a fine way to start the day.

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