A widely used scale to deterimine how pungent peppers are. Measured in Scoville Heat Units.

Originally developed by Wilbur Scoville in 1912, it is the scale of the concentration of capsaicin within a particular type of pepper or chili.

Scoville Units = Pepper variety
0              = Bell, Sweet Italian
100-500        = Peperocini
500-1,000      = New Mexico
1,500-2,500    = Ancho, Passila, Poblano
2,500-10,000   = Jalapeño, Chipotle
5,000-23,000   = Serrano
15,000-30,000  = de Arbol
30,000-50,000  = Piquin, Aji, Cayenne
80,000-300,000 = Habanero, Scotch Bonnet
16,000,000     = Pure Capsaicin

Table source: chemsoc.org

The heat in a chilli comes from a family of chemicals known as capsaicinoids, most commonly capsaicin and dihydrocapsaicin, but also nordihydrocapsaicin, norcapsaicin, homocapsaicin, nornorcapsaicin, and homodihydrocapsaicin,

The original Scoville Organoleptic Test measured the heat level of a chilli by using five human subjects to taste a chilli and record the heat level the capsicanoids caused them to feel.

The test procedure is as follows.

• An alcoholic extract of the chilli to be tested is made.
• A level of extract such that a negative response will be obtained is chosen and diluted with 5% sucrose solution to make a 50ml sample.
• This initial level of extract is increased and the solution remade until three out of five tasters report a burning sensation. Between each iteration the testers should wash their mouths out with water, and wait for five minutes.

These days chilli heat is measured in a slightly more accurate manner, using high-performance liquid chromatography (HPLC) to measure the number of capsaicinoids present in a sample.

Test method taken from the Zarc International website at http://www.zarc.com/english/cap-stun/tech_info/oc/scoville.html