Chilli Heat Is Bought By Variety, Not By Colour

Choosing chillies by how red or how small they look is unreliable. Heat is determined by variety and by the part of the pod, neither of which is visible from outside.

Where the heat is made

Capsaicin is produced in the pale pithy tissue that holds the seeds, not in the flesh and not in the seeds themselves, which only carry it by contact.

So removing seeds reduces heat mainly because the pith comes out with them. A pod deseeded carefully but with the pith left in stays hot.

This is why the same chilli can be used two ways: sliced whole for heat, or with the interior scraped out for its fruity flavour and colour.

Colour indicates ripeness, not strength

Most chillies start green and ripen through to red. Ripening changes sweetness and flavour, and can raise heat somewhat, but a red pod is not automatically hotter than a green one.

A ripe mild variety will be red and gentle, while an unripe hot variety will be green and fierce. The comparison only holds within a single variety.

Size is equally unreliable. Some of the hottest varieties are large and wrinkled, while plenty of small pointed chillies are barely warm.

Growing conditions move the number

Plants under water stress produce more capsaicin, so the same variety grown in different conditions varies considerably in heat between batches.

Which means even a familiar chilli should be tasted before a whole one goes into a pot, especially in dishes where it cannot be removed.

Buying from the same source repeatedly is the practical answer, since consistency comes from the grower rather than from the label on the tray.

Dried and fresh are different ingredients

Drying concentrates heat by weight and changes flavour substantially, producing raisin, tobacco and smoke notes that the fresh pod does not have.

Flakes and powders vary enormously depending on whether the seeds and pith were included and whether the mix is one variety or several.

A generic chilli powder may also contain cumin, garlic and salt, which is a seasoning blend rather than a heat source and should be read before buying.

Heat that arrives late

Capsaicin dissolves in fat and alcohol rather than water, so it spreads through an oil-based dish and keeps building for a while after tasting.

That delay is what causes over-seasoning. A cook tastes, judges the dish mild, adds more, and meets the full heat several minutes later.

Adding chilli in stages with a pause between them, and finishing with fat or dairy if it goes too far, is the only reliable correction once heat is in a pot.