Already in 1912 the American chemist Wilbur Scoville
developed and test and scale with which the hotness
of chili peppers and spicy sauces can be displayed;
the scale of Scoville. This was originally done by taste
tests. We looked at how far a ground pepper had to
be diluted before it was no longer experienced as sharp.
Nowadays it is done by measuring
the concentration of capsaicin.
Capsaicin is a substance that stimulates the receptors on the tongue that are sensitive to heat and pain. This gives a burning feeling. It mainly occurs in hot red or chili peppers. The substance is very stable, hardly evaporates and does not decompose by cooking. Red pepper dishes retain their sharpness even after preparation. The capsaicin that makes the pepper sharp, is mainly in the ribs of the fruit (the internal seed lists). A widespread misunderstanding is that capsaicin is mainly in the seeds.
A dish is experienced by the average Dutchman as spicy around the 500-1000 Scoville units. This is low on the scale of Scoville when you compare this worldwide. Sambal oelek scores on the scale of Scoville 2000. Very sharp peppers are the yellow Madame Jeanette from Suriname and the Habaneropeper from Mexico which is processed in Sambal Gledek. Small dried red or green peppers), called rawit in Indonesia, can also be very hot. The Carolina Reaper has been the hottest pepper in the world since 2012 with an average of 1,569,300 SHU according to Guinness World Records.
That scale, officially called The Scoville Organoleptic Scale, indicates how sharp a chili pepper is. Scoville invented in 1912 for a pharmaceutical company a way to measure how much capsaicin is in a certain pepper, the substance that is called peppers. He discovered that he could not test that in experiments, but that the tongue in this case is a good measuring instrument.
Scoville washed all kinds of peppers in alcohol and diluted the extract with increasing amounts of sugar water until he could no longer taste the sharpness. The degree of dilution determined the sharpness expressed in units of Scoville: 1 part capsaicin extract on 1,000,000 parts water gave a score of 1.5 on the scale of Scoville: a paprika scores 0, jalapeno between 2,500 and 8,000, cayenne 30,000 à 50,000 and pure capsaicin about 15,000,000.
Capsaicin causes a burning sensation on the tongue or in the throat and lingers for a long time because the substance dissolves poorly in water. With a slightly too enthusiastic bite of your Thai soup ('Yes, this is really mild') something greasy, such as milk, softened better.
There is a very different kind of sharp, which burns less on the tongue and in the throat, but rises in the mouth and nasal cavity: wa¬sabi. If you ever take too big a bite, you feel as if a needle is pierced through your nose in your brain. That drops happily quickly.
Wasabi is not on the Scoville scale because it involves a completely different substance, isothiocyanate, a volatile substance that occurs in mustard, broccoli and (Japanese) horseradish, among which wasabi is made. Other spicy ingredients do have a Scoville score, because their sharpness is caused by a similar component. Black pepper grains contain piperine, fresh ginger root contains gingerol.
The Scoville scale is no longer used in practice, because testing with the tongue is not an objective measurement. In order to establish sharpness, there is now a device, the chromatograph, but as a kind of tribute to the pioneer, sharpness is still expressed in Scoville units.