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