Large numbers and scientific-looking acronyms notwithstanding, Scoville’s method isn’t actually that objective. Even trained tasters have a subjective experience, and the tasting palate becomes accustomed to heat, reducing the effect of further chillies. Today, analytical chemists use high-performance liquid chromatography to detect pungency, and translate the results back into Scoville units.
But is one kind of measurement enough? In a recent paper for the journal Appetite, researchers Ivette Guzmán and Paul W. Bosland identified five different sensory characteristics of chilli peppers: development, duration, location, feeling and intensity. The build-up of sensation, the time that sensation lasts, the part of the mouth in which the heat is felt, and the sharpness or flatness of the heat are all taken into account, along with the intensity, still measured in SHU. The heat of a jalapeño is felt on the tongue and lips, while a habanero delivers its payload at the back of the throat.
Guzmán and Bosland’s method is not only sensitive to the presence of different varieties and quantities of capsaicinoid compounds and their complex relationship to human taste receptors. It also provides a basis for the food industry to analyse chilli varieties for their suitability for the cuisines of different cultures. As they point out, Asian diners prefer an intense, sharp heat that comes on rapidly and dissipates quickly, while Hungarian paprika has a moderate buildup of flat heat that is preferable in a central European goulash.
But perhaps some things about chillies cannot be measured at all? The ‘facing heaven pepper’ is both ornamental and widely used in Sichuan cooking: its poetic and aesthetic qualities bring something to every dish cooked with it, beyond its merely chemical properties. Widespread human cultivation has brought a glorious and abundant variety to the chilli pepper, a variety that deserves to be recognised and celebrated.