Scoville scale

The Scoville scale is a system used to measure the spiciness or heat of chili peppers. It was created by American pharmacist Wilbur Scoville in the early 1900s to subjectively measure the concentration of capsaicin, the active component responsible for the heat in peppers. A pepper with more capsaicin is spicier than one with less; thus, it is assigned a higher number of Scoville Heat Units (SHU). The scale ranges from 0 to more than 2.5 million SHU for the hottest chili varieties and cultivars.

The Scoville scale relies on the capsaicinoid sensitivity of people experienced in eating hot peppers. To assess a pepper’s heat, an exact amount of dried, finely ground pepper is mixed with alcohol to extract capsaicin and related capsaicinoid chemicals. This spicy solution is then gradually and methodically diluted in a solution of sugar water until the panel of trained testers can no longer perceive any heat. SHU are assigned on the basis of the amount of dilution required; they are typically presented as a range or average for a given pepper. The scale is linear, meaning that a pepper with a higher SHU is proportionally hotter than one with a lower SHU. For example, a 350,000-SHU habanero is 100 times hotter than a 3,500-SHU jalapeño.

Given that they rely on human testers, Scoville measurements involve a fair degree of subjectivity. Even trained testers vary from one another in their sensitivity to capsaicin, and sensory fatigue from repeated exposure to high levels of heat during a test can affect the results. In addition, individual peppers of the same type can have a range of capsaicin concentrations, depending on their growing conditions and natural genetic variation. Still, the Scoville scale remains a helpful tool for consumers, allowing them to quickly compare the relative heat levels of different peppers.

• green bell pepper: 0 SHU
• poblano: 1,000–2,000 SHU
• jalapeño: 2,500–8,000 SHU
• cayenne pepper: 30,000–50,000 SHU
• tabasco: 30,000–50,000 SHU
• orange habanero: 100,000–350,000 SHU
• ghost pepper: 1 million SHU
• Carolina Reaper: 1.64 million SHU (up to 2.2 million)
• Pepper X: 2.69 million SHU