Why Use Buttermilk

Our answer

Nigella's recipe for Buttermilk Scones (from KITCHEN) is made with a combination of flour, bicarbonate of soda (baking soda) and cream of tartar. The bicarbonate of soda is the leavening ingredient and it needs some acid ingredients to react with to make carbon dioxide bubbles, that cause the scones to rise. Cream of tartar is added to the mixture to provide some acidity. However the scones bake quickly, so the bicarbonate of soda needs to act very fast and some extra acidity is introduced via buttermilk (which is acidic) to speed up the reaction of the bicarbonate of soda. The buttermilk can also add a slight sour tang to the scones, which many people like.

If buttermilk is not available then you can use a 50-50 mixture of low fat plain (natural) yogurt and regular milk. It is also possible to sour milk by adding 1 tablespoon of lemon juice to each 250ml (1 cup) of whole milk. Let the milk and lemon juice mixture stand for a couple of minutes before using. Another option is to try Nigella's recipe for Lily's Scones as this uses regular milk in the recipe and adds extra cream of tartar to boost the acidity instead.