In Bolivia, enjoying the taste and spiciness of a chili is one of the most common things when serving a dish, whether in a llajua, chopped in a salad, in fricassee, or directly in the mouth, as with salteñas. However, describing the level of spiciness of a chili can be very subjective, as it may feel more or less spicy to one person than to another.
Traditionally, to measure the spiciness level, a series of tasters would rate the spiciness of a chili, and then an average of those scores was calculated. But the imprecision of this method led to the exploration of other techniques. Finally, someone came up with a solution to this problem—Wilbur Scoville.
Wilbur Scoville, an American chemist, solved this issue very practically. Aware of the presence of capsaicin, the compound in chili that excites thermic receptors in the skin and mucous membranes (eventually causing irritation), he decided to neutralize it by diluting an extract from a chili sample with water and sugar. The more sugar required in the preparation, the spicier the chili. This test was called the Organoleptic Test.
The effective organoleptic test was used by many for years; however,, and unfortunately, classifying the created scale was not possible—at least not with 100% accuracy—since the capsaicin content, and therefore the spiciness of a chili, varies between samples, even within the same species.
Today, much more precise methods exist, such as chromatography, but they can be costly. Despite this, the spiciness scale still bears the name of Scoville units in honor of the creator of the Organoleptic Test. The scale has been widely adopted; for example: the minimum value, 0 Scoville units, is a green bell pepper or a poblano; a regular locoto ranges between 2,500 and 5,000 Scoville units; pepper spray contains between 2,000,000 and 5,300,000 Scoville units; and the maximum value, 15,000,000 to 16,000,000, is pure capsaicin.
