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Scoville Scale: Quantifying Spiciness
For people who love spicy food, their steel tongue may be a source of pride, but just how hot is that pepper? Read on as Groupon explores the measurement known as the Scoville scale.
Since the human palate varies widely from person to person, determining how spicy something is by taste alone can be a bit like trying to measure the air temperature based on how much someone is sweating. Like a thermometer for the spiciness of peppers, the Scoville scale cuts through this sensory subjectivity by measuring the prevalence of capsaicin—the chemical compound responsible for delivering the spicy flavor—in chili peppers or foods that use them for pungent effect. The capsaicin content determines how many Scoville Heat Units (or SHU) are in a given food. A standard jalapeño pepper, for example, has somewhere between 2,500–5,000 SHU, whereas the hottest pepper in the world, the Carolina Reaper, checks in at around 2.2 million SHU. (Just for comparison, police-grade pepper-spray measures a fiery 5.3 million SHU, which is why it’s banned as an ingredient in most chili-cooking competitions.)
Named after its inventor, the Scoville scale dates back to 1912. While attempting to find a suitable pepper to use in an ointment, pharmacist Wilbur Scoville developed a process called the Scoville organoleptic test, which relied on human taste-testers to judge the piquancy of chili-pepper extracts. Subjects would taste the extract in its pure form then continue to sample it as Scoville diluted it with water. The degree to which a pepper’s extract had to be diluted before subjects could no longer feel the heat determined its placement on the scale. Today, a process called high-performance liquid chromatography can determine the exact concentration of capsaicin, eliminating the need for human taste testers. That’s probably for the best, since it might be dangerous to test the limitations of the human tongue; in 2013, the United Kingdom’s Daily Mail reported a story of a British doctor who broke into tears and hallucinations after (voluntarily) consuming a curry that measured 6 million SHU.