The scoville hot pepper scale  

The Scoville scale is the measurement of the pungency (spicy heat) of chili peppers or other spicy foods 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.

The Scoville scale is an empirical measurement dependant on the capsaicin sensitivity of testers and so not a precise or accurate method to measure capsaicinoid concentration, however, capsaicin concentration can very roughly be estimated as ~18µM/SHU.

In Scoville’s method, a measured amount of alcohol extract of the capsaicin oil of the dried pepper is produced, after which a solution of sugar and water is added incrementally until the “heat” is just barely detectable by a panel of (usually five) tasters; the degree of dilution gives its measure on the Scoville scale. Thus, a sweet pepper or a bell pepper, containing no capsaicin at all, has a Scoville rating of zero, meaning no heat detectable.The hottest chilis, such as habaneros and nagas, have a rating of 200,000 or more, indicating their extract must be diluted over 200,000 times before the capsaicin presence is undetectable.The greatest weakness of the Scoville Organoleptic Test is its imprecision, because it relies on human subjectivity. Tasters are given only one sample per session. Results vary widely, up to 50%, between laboratories.

Since Scoville ratings are defined per unit of dry mass, comparison of ratings of between products having different water content can be misleading. Typical fresh chili peppers have a water content around 90 percent, whereas, for example, Tabasco sauce has a water content of 95 percent.For law-enforcement-grade pepper spray, values from 500 thousand up to 5 million SHU have been mentioned,but the actual strength of the spray depends on the dilution, which could be a factor of 10.

The chilis with the highest rating on the Scoville scale exceed one million Scoville units, and include specimens of naga jolokia or bhut jolokia and its cultivars.

Numerical results for any specimen vary depending on its cultivation conditions and the uncertainty of the laboratory methods used to assess the capsaicinoid content. Pungency values for any pepper are variable, owing to expected variation within a species—easily by a factor of 10 or more—depending on seed lineage, climate (humidity is a big factor for the Bhut Jolokia; the Dorset Naga and the original Naga have quite different ratings), and even soil (this is especially true of habaneros). The inaccuracies described in the measurement methods above also contribute to the imprecision of these values. When interpreting Scoville ratings, this should be kept in mind.

When selecting peppers or attempting to gauge the relative hotness of each pepper, the Scoville scale can be useful for comparison purposes. Note, however, that while certain breeds of hot pepper have been known to fall within a certain range, depending on the conditions where it was grown, it may be hotter or sweeter than rated. No matter what the Scoville scale says about the pepper you’re eating, you should certainly exercise caution when handling or consuming hot peppers.

The Scoville scale is the rating that is used to determine the hottest pepper in the world according to the Guiness Book of World Records. Scoville heat units are also used among pepper cultivators and vendors, so it’s a good idea to have this page bookmarked as a reference. As more peppers are discovered and studied, we’ll be updating this page with the latest information about peppers and how they rate on the Scoville scale.