How is the heat of a chilli measured?
In 1912 a chemist called Wilbur L. Scoville, devised a dilution method to calculate how hot chillis were. He added equal parts of sugar water to the capsicum oil until the burn could no longer be detected.
The very mild chillis could take as much a 1000 units before the burn disappeared. Can you imagine the exercise when working out the rating of the Red Savina Habanero, which achieves a rating in excess of 500 000 Scoville units.
Nowadays chillis are measured using a separating technique called High Pressure Liquid Chromatography. A measure of extracted chilli juice is placed into the chromatograph machine, and under high pressure, the machine separates the capsaicin from the total volume of liquid and thus calculates the strength of the chilli.
What is all of that heat designed to do in nature?
Nature, as always, is wonderful! The most obvious reason for why chillis burn is that the plant wants to disperse its seeds in the most efficient way possible.
The answer is birds! Birds don’t have trigeminal cells in their mouths throats or noses, as do mammals. The seeds pass through a bird’s digestive tract very quickly, and are dispersed unharmed by digestive juices over a large area relatively quickly. A mammal on the other hand is quite different.
The seeds hardly ever make it through the system whole and unscathed, because of the powerful acidic gastric juices needed to break food down during digestion.
In a nutshell, chillis are trying their utmost to stop us and other herbivores from eating them by producing capsaicin oil as a repellent.
I think that they have to rethink their strategy, because it certainly isn’t working with me.