The Scoville Scale

A chilli’s heat can vary considerably for a few reasons, mainly genetics and environment. The plant’s genetic makeup will affect how much capsaicin is produced; this also differs between varieties. For example, the Kashmiri chilli produces very little heat and clocks in at 1,000 to 2,000 Scoville Heat Units (SHU), but the fiery cayenne chilli registers at 30,000 to 50,000 SHU.

Soil, water, climate, and other environmental factors affect the amount of capsaicin produced; for example, if a low-heat-producing chilli plant is grown under stressful conditions, the plant will adapt and produce hotter chillies.