You may find you find some things impossible to eat, whilst others relish it. Is it just down to personal taste or can “hotness” really be measured. As it turns out yes! The Scoville scale, named after its creator Wilbur Scoville, measures the heat of a chilli in Scoville heat units (SHU). But what is it measuring? A compound known as capsaicin stimulates nerve endings in the skin, like on the tongue. SHUs thus show the amount of capsaicin present in a given chilli. The scale ranges from 0 (bell peppers for example) to 16,000,000 (pure capsaicin) and encompasses a wide variety of peppers. There are different methods of measuring SHUs. The first – developed by Scoville – is called the Scoville Organoleptic Test. It entails extracting the capsaicin oil from a dried pepper, adding it to varying amounts of sugared water and putting it through a taste test. When the heat is detectable by palate, the dilution will give the rating on the Scoville scale. Other more scientific methods can be used, like high-performance liquid chromatography which directly measures the concentration of capsaicinoid. The degree of variation in people’s reactions to chillies is most probably down to variations in nerve endings and the receptor cells stimulated by capsaicin. See if you can find your favourite chilli on the chart!