Scoville scale

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A display of hot peppers and the Scoville scale at a supermarket in Houston, Texas

The Scoville scale is the measurement of the pungency (spicy heat) of chili peppers or other spicy foods reported in Scoville heat units (SHU),[1] 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.[2]

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.

Scoville organoleptic test[edit]

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.[3] 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.[citation needed] 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.[4]

High-performance liquid chromatography[edit]

Naga Jolokia (bhut jolokia, naga morich) is rated at over one million Scoville units. It is primarily found in Northeast Indian states of Assam, Nagaland, and Manipur. It is also found in Bangladesh.
The Red Savina pepper, one of the hottest chilis, is rated at around 250,000 Scoville units.[5]

Spice heat is usually 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 weighs 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.[6][7][8] 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.

List of Scoville ratings[edit]

Scoville ratings of chemicals[edit]

Scoville heat unitsExamples
8,600,000Homocapsaicin, homodihydrocapsaicin

Scoville ratings of peppers[edit]

Scoville heat unitsExamples
1,500,000–2,000,000Trinidad Moruga Scorpion[9] Carolina Reaper[10]
855,000–1,463,700Naga Viper pepper,[11] Infinity Chilli,[12] Bhut Jolokia chili pepper,[13][14] Trinidad Scorpion Butch T pepper,[15] Bedfordshire Super Naga,[16] 7-Pot Chili
350,000–580,000Red Savina habanero[17]
100,000–350,000Habanero chili,[18] Scotch bonnet pepper,[18] Datil pepper, Rocoto, Piri Piri Ndungu, Madame Jeanette, Peruvian White Habanero,[19] Jamaican hot pepper,[20] Guyana Wiri Wiri, Fatalii [21]
50,000–100,000Byadgi chilli, Bird's eye chili (aka. Thai Chili Pepper),[22] Malagueta pepper,[22] Chiltepin pepper, Piri piri (African bird's eye), Pequin pepper,[22] Siling Labuyo (native chili cultivar from the Philippines)
30,000–50,000Guntur chilli, Cayenne pepper, Ají pepper,[18] Tabasco pepper, Cumari pepper (Capsicum Chinese)
10,000–23,000Serrano pepper, Peter pepper, Aleppo pepper
3,500–8,000Espelette pepper, Jalapeño pepper, Chipotle,[18][23] Guajillo pepper, New Mexican peppers,[24] Hungarian wax pepper, Tabasco sauce
1,000–2,500Anaheim pepper (cultivar of New Mexican peppers),[24] Poblano pepper, Rocotillo pepper, Peppadew, Sriracha sauce,[25] Gochujang
100–900Pimento, Peperoncini, Banana pepper, Cubanelle
No significant heatBell pepper, Aji dulce

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.[26] For law-enforcement-grade pepper spray, values from 500 thousand up to 5 million SHU have been mentioned,[27] but the actual strength of the spray depends on the dilution, which could be a factor of 10.[28]

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, the "Jalapenó" and the "Ghost chili", neither of which has official cultivar status.[29][30]

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.[4]



  1. ^ Peter, KV, ed. (2001), Handbook of Herbs and Spices 1, CRC Press, p. 120, ISBN 0-8493-1217-5 .
  2. ^ The Journal of the American Pharmacists Association 1, 1912: 453–4 .
  3. ^ Bosland, Paul W.; Walker, Stephanie J. (February 2010). "Measuring Chile Pepper Heat". New Mexico State University Cooperative Extension Service, Guide H-237. Retrieved August 21, 2012. 
  4. ^ a b Tainter, Donna R.; Anthony T. Grenis (2001). Spices and Seasonings. Wiley-IEEE. p. 30. ISBN 0-471-35575-5. "Interlab variation [for the original Scoville scale] could be as high as +/−50%. However, labs that run these procedures could generate reasonably repeatable results." 
  5. ^ DeWitt, Dave; Bosland, Paul W. (2009). The Complete Chile Pepper Book. ISBN 978-0-88192-920-1. 
  6. ^ M.D. Collins et al., "Improved Method for Quantifying Capsaicinoids in Capsicum Using High-performance Liquid Chromatography". HortScience 30 137–139 (1995).
  7. ^ C.O. Nwokem et al., Determination of Capsaicin Content and Pungency Level of Five Different Peppers Grown in Nigeria. New York Science Journal 2010;3(9)
  8. ^ Z.A. Al Othman et al., Determination of Capsaicin and Dihydrocapsaicin in Capsicum Fruit Samples using High Performance Liquid Chromatography. Molecules 2011, 16, 8919–8929
  9. ^ "Chile experts identify Trinidad Moruga Scorpion as world's hottest". The Daily Telegraph (UK). 2012-02-16. 
  10. ^ ""Smokin' Ed's Carolina Reaper® wins Guiness World Record–Smokin’ Ed’s Carolina Reaper® Officially the hottest chili pepper in the world!". PuckerButt Pepper Company. November 14, 2013. Retrieved November 20, 2013. 
  11. ^ Dykes, Brett Michael (3 December 2010). "World’s hottest pepper is ‘hot enough to strip paint’". Yahoo! News. Retrieved 2010-12-03. 
  12. ^ "Grantham's Infinity chilli named hottest in world". BBC. 2011-02-18. 
  13. ^ Shaline L. Lopez (2007). "NMSU is home to the world's hottest chile pepper". Archived from the original on 2007-02-19. Retrieved 2007-02-21. 
  14. ^ "World's hottest chili pepper a mouthful for prof". CNN. AP. 23 February 2007. Archived from the original on 2007-03-22. 
  15. ^ Matthew Da Silva, "Aussies grow world's hottest chilli", Australian Geographic, 12 April 2011
  16. ^ "UK's hottest commercially grown chilli pepper goes on sale". 
  17. ^ "World's hottest chile pepper discovered". American Society for Horticultural Science. Retrieved 2008-03-31. 
  18. ^ a b c d "Chile Pepper Heat Scoville Scale". Retrieved 2006-09-25. 
  19. ^ "Habanero White". Chile man. Retrieved 2011-09-21. 
  20. ^ "The Scoville Scale". 
  21. ^ Scoville Food Institute, Periodic Table of Scoville Units.
  22. ^ a b c "Scoville Scale Chart for Hot Sauce and Hot Peppers". Scott Roberts. Retrieved 2008-11-19. 
  23. ^ "Scoville hot sauce heat scale". 
  24. ^ a b "Chile Cultivars of NMSU" (PDF). Chile Pepper Institute at New Mexico State University. 2008. Retrieved 2013-08-09. 
  25. ^ "Gochujang, divide 5 hot grade". Herald Economy. 
  26. ^ USDA nutrient database for Peppers, jalapeno, raw (92% water content); Peppers, hot chili, red, raw (88% water content); Red Tabasco sauce (95%)
  27. ^ "Chemical hazards in law enforcement". The Police Policy Studies Council. Retrieved 2009-02-09. "Most law enforcement sprays have a pungency of 500,000 to 2 million SHU. One brand has sprays with 5.3 million SHU." 
  28. ^ "The Truth About Defensive Spray Heat". Sabre red. "Sabre Red = 10% OC @ 2,000,000 Scoville Heat Units. Thus, 90% of the formulation dilutes the 2,000,000 SHUs creating a Scoville Content of 200,000." 
  29. ^ "World’s hottest chilli grown in Grantham, Lincs". The Daily Telegraph (London). 2010-04-01. Retrieved 2010-04-24. 
  30. ^ "Grantham firm grows world's hottest chilli". UK: This is Lincolnshire. Retrieved 2010-04-24.