The Chilli Guru

Capsaicin and Capsaicinoids

Plants of the genus Capsicum produce two related groups of chemicals which are unique to the genus: capsaicinoids and capsinoids. Capsaicinoids, of which the most abundant and most pungent is capsaicin, are what make chillies taste hot. Both capsaicinoids and capsinoids contribute to the health benefits of eating chillies, so even chillies which exhibit little or no pungency are beneficial.


The pungency of a chilli is measured in Scoville Heat Units (SHUs). This is a measure of how much a chilli has to be diluted with bland food for the pungency to be undetectable. The system was devised by Wilbur Scoville who fed pureed chilli mixed with sugar water to a panel of volunteers. The technique lacked precision and has now been replaced by more scientific methods.

Pure capsaicin has a Scoville rating of sixteen million, while the hottest chillies can reach over two million. To put this in perspective, a five gram chilli with a 2 million SHU rating would need to be mixed with 10 tons of other food for the heat to be undetectable.

Capsinoids have a rating of about 16 thousand SHUs and so contribute virtually nothing the the pungency of chillies.

Heat Quality

There are five naturally occurring capsaicinoids which vary in pungency between 8 million and 16 million SHUs. Their heat varies, however, not just in the intensity but also in the quality. Foods flavoured with most chillies exhibit an immediate burning sensation in the mouth. Subsequent mouthfuls have progressively less impact and the glow fades quickly after the dish is finished. Other chillies have a very different impact, which we may term 'slow burn'. The initial sensation is very muted - the food seems to have very little pungency. Each mouthful, however, adds to the heat and the glow continues building even after the meal is finished. Which capsaicinoids contribute to each effect is poorly documented, but slow burn chillies are valued because the pungency is both less aggressive and longer lasting.

Chillies and health

Extravagent claims have been made about the health benefits of eating chillies, mostly supported only by anecdotal evidence. A feeling of well being and a cooling effect in hot weather are well attested, but reductions in blood pressure and heart disease are not regarded as medically proven. Still, anecdotal evidence is plentiful and positive thinking is known to be beneficial, so eat, enjoy and feel the buzz.

© 2016-21 The Chilli Guru™