El Yucateco is a very hot green chili sauce made from habanero peppers, one of the hottest there is. For this sauce green does not mean mild.
Water is not the answer
For the un-initiated a teaspoon of this sauce is sufficient for all but the most enthusiastic chili head. When you use el yucateco hot chili sauce, keep a glass of milk or pot of plain yoghurt to hand. The reason is simple; capsaicin is an oil and so does not dissolve in or mix with water, it is hydrophobic. This means swilling your mouth with water will only transfer the capsaicin all over your mouth, ouch! Milk and yoghurt contain a substance called casein, which disrupts the chemical reaction that capsaicin causes.
How does this work?
When the capsaicin contained in el yucateco sauce interacts with the nerve receptors on the tongue the nerve is stimulated. The capsaicin causes the receptor to stay open giving the kick and sensation we associate with chili dishes and sauces, as long as capsaicin is in the mouth, you will feel the sensation. Capsaicin is in effect telling your peripheral and central nervous system that your mouth is on fire. The opposite response is elicited by chemicals inside mint leaves. Casein is an enzyme (proteins which catalyze biochemical reactions), which inhibits the interaction between the capsaicin and the nerve and pain receptors in the tongue and mouth.
The Scoville scale (350,000 – 580,000)
In 1912 a chemist called Wilbur Scoville developed a scale to measure the level of heat intensity that a particular chili will produce. On this scale cayenne pepper is 30-50,000 Scoville Heat Units (SHU), the number is derived from the measurement of dilution in sugared water that did not necessitate reaching for the yoghurt. It is clearly subjective and depends on the individual. To give you an idea the habanero pepper in el yucateco sauce measures 350-580,000 SHU’s, ten times hotter than cayenne pepper. Overall about two thirds up the scale.
Modern chemistry uses a technique called high performance liquid chromatography. The chili pods are ground and the active ingredients extracted and transported through an organic solvent. Then the exact number of individual capsaicin molecules from a particular chili is determined by analysis.