Chilli Heat Explained: SHU vs Capsaicin
Chilli heat is measured in Scoville Heat Units (SHU) — a proxy for capsaicin concentration. But heat is not flavour, and it is not linear. Understanding both is what makes a specification reliable.
What SHU actually measures
SHU quantifies the concentration of capsaicin, the compound that triggers the heat sensation on the palate. Sweet pepper registers under 500 SHU; the hottest common Chinese varieties — Jixin, Chilli King — exceed 50,000 SHU. The number is a concentration, not a "taste strength", which is why two chillies can share an SHU rating yet feel very different.
Heat is non-linear — dose accordingly
A small amount of a 50,000+ SHU variety moves a blend's heat far more than the same weight of a 10,000 SHU variety. In practice this means extra-hot chillies are usually blended as an accent, and precise SHU windows — not "hot" or "medium" — are what keep a product consistent batch to batch.
Heat vs colour vs flavour
Three separate properties, controlled independently. Heat (capsaicin, SHU) is what burns; colour (carotenoids, ASTA) is what tints red; flavour (aroma compounds) is what you taste. A complete specification names all three — which is why a variety name beats a generic "chilli powder". See high heat and mesh size for the practical next steps.
Frequently Asked Questions
What is SHU and how is chilli heat measured?
SHU (Scoville Heat Units) measures chilli heat as the concentration of capsaicin — the compound that triggers the heat sensation. The higher the SHU, the hotter the chilli: sweet pepper is under 500 SHU, while extra-hot varieties exceed 50,000 SHU.
Is chilli heat linear?
No. Heat is non-linear: a small amount of a 50,000+ SHU variety moves a blend's heat far more than the same weight of a 10,000 SHU variety. That is why precise SHU windows matter in a specification.
What is the difference between heat and flavour?
Heat (capsaicin, measured in SHU) and flavour (aroma compounds) are separate and vary independently. Two chillies can share the same SHU but taste completely different — another reason to name the variety, not just the heat.