About the Scoville Heat Scale

 

The Scoville scale is the measurement of the pungency (spicy heat) of chili peppers or other spicy foods as reported in Scoville heat units (SHU), a function of capsaicin concentration. The scale is named after its creator, American pharmacist Wilbur Scoville. His method, devised in 1912, is known as the Scoville Organoleptic Test.

 

Unlike methods based on high-performance liquid chromatography, the Scoville scale is an empirical measurement dependent on the capsaicin sensitivity of testers and so is not a precise or accurate method to measure capsaicinoid concentration.

 

In Scoville's method, an exact weight of dried pepper is dissolved in alcohol to extract the heat components (capsinoids), then diluted in a solution of sugar water.  Increasing concentrations of the extracted capsinoids are given to a panel of five trained tasters, until a majority (at least three) can detect the heat in a dilution. The heat level is based on this dilution, rated in multiples of 100 SHU.

 

A weakness of the Scoville Organoleptic Test is its imprecision due to human subjectivity, depending on the taster's palate and their number of mouth heat receptors, which varies greatly among people.  Another weakness is sensory fatigue: the palate is quickly desensitised to capsaicins after tasting a few samples within a short time period.  Results vary widely, ± 50%, between laboratories.