Scoville Heat Units (SHU) are the standard measurement used to determine the heat level or pungency of chili peppers. This scale measures the highest dilution of a chili pepper extract at which its heat can still be detected by a taste panel. For more on the history of the Scoville scale, check out this detailed overview from Science Direct.

While Scoville Heat Units provide a way to gauge the intensity of pepper heat, the method has some limitations. The Scoville organoleptic test, which relies on human taste panels, can be subjective. Variability in taster sensitivity, based on individual palate and the number of heat receptors, can lead to inconsistent results. For more about the subjectivity of human taste tests, you can explore this article on sensory testing from the National Institutes of Health.

Additionally, sensory fatigue can affect the accuracy of the test—after sampling a few peppers, a taster’s palate becomes desensitized to capsaicinoids, the compounds responsible for heat. This can lead to results that differ by up to ±50% between laboratories. To better understand how capsaicinoids work in the body, check out this study on capsaicinoid receptors