Buttermilk Substitute in Red Velvet Cupcakes

Our answer

Many red velvet cake recipes, including Nigella's Red Velvet Cupcakes (from Kitchen and also on the Nigella website,) use buttermilk in the batter. The acidity in buttermilk is important as it is needed to react with the bicarbonate of soda (baking soda) to make the cupcakes rise. Sour cream is a possible alternative as it is acidic, but buttermilk has a very low fat content whereas sour cream has a fat content around 15-20% and this can affect the texture of the cupcakes.

We would instead prefer to use a low fat plain/natural yogurt mixed with milk as an alternative to buttermilk. Use about 3/4 of the volume in yogurt and 1/4 in milk, so for Nigella's recipe you would need 125ml yogurt and 50ml milk (1/2 cup plus 1 tablespoon yogurt and 3 tablespoons milk). If this is not available then you can make a substitute for buttermilk by souring some milk. To each 250ml (1 cup) milk you add 1 tablespoon lemon juice and let it stand for 10 minutes before using it. For Nigella's recipe you would need 175ml (3/4 cup) milk and 2 1/4 teaspoons lemon juice.