Scoville scale

The Scoville scale is a measurement of the pungency (spicy heat) of chili peppers, Ghost Peppers, the world's hottest pepper, the Carolina Reaper, 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.

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Pepper stand at Central Market in Houston, Texas, with Scoville scale.

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.

Scoville organoleptic test

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Naga Jolokia (bhut jolokia, naga morich) is rated at over one million Scoville units. It is primarily found in the Northeast Indian states of Assam, Nagaland, and Manipur. It is also found in Bangladesh.

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 no longer 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.

Scoville ratings

Considerations

Since Scoville ratings are defined per unit of dry mass, comparison of ratings 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 500,000 up to 1 million SHU have been mentioned, but the actual strength of the spray depends on the dilution, which could vary by 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 cultivar, the "Ghost chili", which does not have official cultivar status. The Carolina Reaper is currently the highest rated pepper in the world.

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.

Peppers

Scoville heat units	Name of pepper
1,600,000 – 2,200,000	Carolina Reaper
855,000 – 2,199,999	Komodo Dragon Chili Pepper, Trinidad Moruga Scorpion, Naga Viper pepper, Infinity Chilli, Naga Morich, Bhut Jolokia (ghost pepper), Trinidad Scorpion Butch T pepper, Bedfordshire Super Naga, Spanish Naga Chili
350,000 – 580,000	Red Savina habanero
100,000 – 350,000	Habanero chili, Scotch bonnet pepper, Datil pepper, Rocoto, Madame Jeanette, Peruvian White Habanero, Jamaican hot pepper, Fatalii Wiri Wiri
100,000 – 225,000	Bird's eye chili
50,000 – 100,000	Byadgi chilli, Malagueta pepper, Chiltepin pepper, Piri piri, Pequin pepper, Siling Labuyo
30,000 – 50,000	Guntur chilli, Cayenne pepper, Ají pepper, Tabasco pepper, Capsicum chinense, Serenade chilli
10,000 – 23,000	Serrano pepper, Peter pepper, Chile de árbol, Aleppo pepper, Chungyang Red Pepper
3,500 – 10,000	Guajillo pepper, Espelette pepper, Fresno pepper, Jalapeño, wax (e.g., Hungarian wax pepper)
1,000 – 4,000	Jalapeño pepper,Gochujang, Pasilla pepper, Peppadew, poblano (or ancho), Poblano verde, Rocotillo pepper
100 – 900	Banana pepper, Cubanelle, paprika, Peperoncini, Pimento
0	Bell pepper

Chemicals

Scoville heat units	Examples
16,000,000,000	Resiniferatoxin
5,300,000,000	Tinyatoxin
16,000,000	Capsaicin
15,000,000	Dihydrocapsaicin
9,200,000	Nonivamide
9,100,000	Nordihydrocapsaicin
8,600,000	Homocapsaicin, Homodihydrocapsaicin
160,000	Shogaol
100,000	Piperine
60,000	Gingerol
16,000	Capsiate

ASTA pungency units

The Red Savina pepper, one of the hottest chilis, is rated at around 500,000 Scoville units.

Since at least the 1980s, spice heat has been more precisely measured by a method that uses high-performance liquid chromatography (HPLC). This identifies and measures the concentration of heat-producing chemicals. The measurements are used in a mathematical formula that weights them according to their relative capacity to produce a sensation of heat. This method yields results, not in Scoville units, but in American Spice Trade Association (ASTA) pungency units. A measurement of one part capsaicin per million corresponds to about 15 Scoville units, and the published method says that ASTA pungency units can be multiplied by 15 and reported as Scoville units. Scoville units are a measure for capsaicin content per unit of dry mass. This conversion is approximate, and spice experts Donna R. Tainter and Anthony T. Grenis say that there is consensus that it gives results about 20–40% lower than the actual Scoville method would have given.

External links

• Wilbur Scoville profile on NNDB
• Scoville Scale Chart for Hot Sauce and Hot Peppers Scoville Heat Scale Database on Scott Roberts Website
• Scoville Scale/Scoville Heat Units Explanation at Tabasco web site