Choosing cocoa powder

Natural cocoa sits at pH 5.3–5.8 and is acidic; Dutch-process has been alkalised to 6.8–8.1 and is not. That single difference decides the leavening: natural cocoa reacts with baking soda to produce lift, and Dutch-process does not.

A recipe calling for natural cocoa and baking soda, made with Dutch-process, gives a flat dense cake. Recipes written for Dutch-process use baking powder, which carries its own acid.

Flavour follows: natural is fruitier and sharper with a reddish tone; Dutch-process is smoother and darker.

Cocoa powder runs from about 10% to 24% fat depending on how hard it was pressed, and the number is often on the tin. Higher-fat powder gives a richer result and a more tender crumb; low-fat powder is drier and cheaper.

For drinking chocolate and for rich bakes, 20–24% is worth paying for. For a recipe with plenty of butter, it matters less.

Black cocoa is heavily alkalised, near-black, very low in fat and largely stripped of flavour. It is a colour ingredient — the reason cream-filled sandwich biscuits look as they do — and is normally blended at a quarter to a third of the total cocoa rather than used alone.

Raw cacao powder is unroasted or lightly processed and tastes noticeably more acidic and less developed. Whether that is a feature is a preference.