Buttermilk in pancakes: what it does and how to substitute it

The short answer: Buttermilk does two things in pancakes that regular milk cannot. Its acidity reacts with bicarbonate of soda (baking soda) to produce carbon dioxide bubbles, giving the batter lift as it cooks. It also tenderises gluten, producing a softer, more delicate crumb than a milk-only batter. If you don't have buttermilk, a tablespoon of lemon juice or white wine vinegar stirred into 240ml of regular milk makes a reliable substitute.

Buttermilk appears in more pancake recipes than almost any other single ingredient. The American buttermilk stack is built entirely around it. Several classic British recipes call for it too. Yet it is one of the ingredients most likely to be absent from a British refrigerator, and the one most likely to be in a bottle that's been open for two weeks longer than it should have been.

This article covers what buttermilk actually does in a pancake batter — chemically, structurally, texturally — and what you can use instead when you don't have it.

What is buttermilk?

Modern buttermilk is almost always cultured buttermilk: regular skimmed or semi-skimmed milk that has been fermented with lactic acid bacteria, in the same way that yoghurt is fermented. The result is a thick, slightly tart liquid with a pH of around 4.4 to 4.6 — significantly more acidic than fresh milk, which sits at around pH 6.7.

The name is a historical holdover. Traditional buttermilk was the thin, watery liquid left behind after churning cream into butter — mildly acidic and very low in fat. The cultured product sold in modern supermarkets is a deliberate approximation: made to behave the same way in baking without relying on a butter-churning by-product that barely exists at industrial scale any more.

Fat content varies by brand. Most British buttermilk contains less than 1% fat; US buttermilk is similarly thin. Neither is a cream product, despite some recipe writing that treats it as interchangeable with soured cream.

What buttermilk does in pancakes

The two functions are distinct and should be understood separately, because substitutes that replicate one do not always replicate the other.

1. Chemical leavening

Bicarbonate of soda (baking soda) is an alkali. When it meets an acid in a wet batter, it reacts to produce carbon dioxide gas. Those gas bubbles become the air pockets that make a pancake light rather than dense.

Buttermilk is the acid that triggers this reaction. The more buttermilk used, the more vigorous the reaction — and, up to a point, the airier the pancake. This is why buttermilk stack recipes typically call for bicarbonate of soda as their primary raising agent rather than baking powder. (Baking powder contains its own acid and works without buttermilk; the two are not interchangeable without adjusting quantities.)

The reaction is fast. Once buttermilk and bicarbonate of soda are combined, you have perhaps 30 minutes before the available carbon dioxide has been produced and the batter starts to lose its lift. A brief rest improves gluten relaxation, but don't leave the batter for hours if you're relying on the leavening effect.

2. Gluten tenderisation

Gluten forms when the proteins in flour — glutenin and gliadin — come into contact with water and are worked by mixing. The longer you mix, and the higher the protein content of the flour, the stronger and tougher the gluten network becomes.

Acid weakens gluten bonds. The lactic acid in buttermilk partially breaks down the gluten structure as the batter rests, producing a more tender crumb and a more delicate texture. This is why buttermilk pancakes have a specific quality — slightly cottony, just yielding — that milk-only pancakes don't quite achieve, even when the baking soda chemistry is otherwise matched.

It also means buttermilk batters are more forgiving of over-mixing than milk-based ones: the acid compensates for some of the toughening effect of vigorous whisking.

The four working substitutes

All four substitutes work by mimicking buttermilk's acidity. None perfectly replicates the flavour or texture of the original, but each is close enough that the average pancake won't suffer noticeably.

Milk and lemon juice

Add 1 tablespoon of fresh lemon juice to 240ml (1 cup) of whole milk. Stir briefly and let it sit for five minutes. The milk will curdle slightly — this is correct. The pH drops to approximately the same range as cultured buttermilk.

This is the most commonly recommended substitute and the most reliable one. The lemon flavour is mild enough to be undetectable in the cooked pancake. Use it in a 1:1 ratio with buttermilk in any recipe.

Milk and white wine vinegar

Same ratio: 1 tablespoon of white wine vinegar (or distilled white vinegar) per 240ml of milk, left to stand for five minutes. The result is chemically near-identical to the lemon juice version. The vinegar flavour does not survive cooking.

Plain yoghurt thinned with milk

Yoghurt has a similar pH to buttermilk — typically around 4.0 to 4.6, depending on the brand and fermentation time. Thin plain yoghurt with milk to achieve a pourable consistency: roughly 180g of full-fat yoghurt mixed with 60ml of milk approximates 240ml of buttermilk.

This is the closest substitute in texture and flavour, particularly if you use a good-quality live yoghurt. The result is slightly richer than a standard buttermilk batter. If the only yoghurt you have is low-fat, increase the proportion of yoghurt and reduce the milk slightly — the acid matters more than the fat content here.

Kefir

Plain, full-fat kefir — the fermented milk drink stocked by most British supermarkets — is an excellent buttermilk substitute that few recipes mention. Its pH, fat content, and thin, pourable consistency are all close to cultured buttermilk. Use it 1:1 in place of buttermilk. The flavour is slightly more pronounced than cultured buttermilk but does not intrude in a cooked pancake.

What does not work well

Skimmed or semi-skimmed milk alone, without an acid added, will not replicate buttermilk's leavening effect — the bicarbonate of soda will not have the acid it needs to react properly. The pancake will be flat and slightly dense.

Plant-based milks require more care. Soy milk acidified with lemon juice or vinegar is the closest plant-based substitute and works reasonably well. Oat milk and almond milk produce a visually similar curdled result but with more variable acidity, which can make the leavening unpredictable. If you regularly cook with plant-based milks, test with a small batch first before committing to a full recipe.

Soured cream diluted with milk also works — roughly 120ml soured cream plus 120ml milk to replace 240ml of buttermilk — but produces a noticeably richer, denser pancake and is the most divergent of the substitutes.

Buttermilk in British supermarkets

Buttermilk is less common in British kitchens than American ones, largely because it does not feature as prominently in British baking traditions. Most UK supermarkets — Tesco, Sainsbury's, Waitrose, Marks & Spencer, Ocado — stock it in the dairy or yoghurt aisle, typically in 300ml or 500ml bottles. That creates the common problem of leftover buttermilk: the recipe uses 240ml, the bottle holds 500ml, and the remainder sits at the back of the fridge for a fortnight.

Once opened, cultured buttermilk keeps for approximately 7–10 days refrigerated. Its high acidity makes it reasonably resistant to spoilage, but the flavour grows more sour with time. Beyond 10 days, taste before using. Buttermilk freezes well for up to three months — it separates on thawing, but a quick stir recombines it and the chemistry is unaffected.

When buttermilk makes the biggest difference

Buttermilk has the biggest impact in recipes where it is the primary acid — that is, recipes calling for bicarbonate of soda as the only raising agent, with no baking powder. In those recipes, omitting the buttermilk (or using a substitute without sufficient acidity) produces noticeably flatter, denser pancakes.

In recipes that use baking powder as the primary raising agent and add buttermilk mainly for flavour and tenderness, the effect is subtler. The pancakes will still rise without it; they'll simply be slightly less tender and lack the mild tang buttermilk contributes.

For the fullest buttermilk effect, the American buttermilk stack recipe is built around bicarbonate of soda rather than baking powder, with a brief resting period that lets the acid work on the gluten before the batter hits the pan. It is the clearest demonstration of what buttermilk actually does when you use it properly.