Chilies

Chilies are the most widely grown spice in the world. Capsaicin is the active ingredient that gives chilies their "spicyness." In terms of evolution, the chili peppers developed capsaicin as a chemical repellant against mammals, whose teeth grind up the fruit and destroy the seeds. Birds, on the other hand, are immune to capsaicin. They swallow the fruits whole and disperse the seeds widely.

Capsaicin is synthesized by the surface cells of the placenta - the pithy tissue that bears the seeds. It accumulates in droplets just under the cuticle of the placenta surface, not on the seeds, but it can coat the seeds quickly if that cuticle is placed under pressure. Some capsaicin enters the body of the fruit via the plant's circulation.

Capsaicin pungency is strongest before ripening. The hottest chilies are the ones picked around the time they start to change colors. There are different versions of the capsaicin molecule which account for the difference in pungency - quick and transient or slow and persistent.

The effects of capsaicin on the body are many. It affects the body's temperature regulation. It makes us feel hot thus activating our cooling mechanism of sweating and increased blood flow to the skin. Capsaicin increases metabolic rate and triggers brain signals to make us feel less hungry and more satisfied. (Weight loss, anyone?) Capsaicin is a skin and eye irritant. Its oily nature makes it difficult to wash off surfaces, so care must be taken when handling chilies.

To quench the burn, try something either cold (ice) or solid and rough (rice, crackers, a spoonful of sugar). Cold liquid cools the receptors below the tempertature at which they are activated. Cold water does not help as much because capsaicin is not water-soluble. Water distributes more capsaicin particles to the mouth. Cold milk is more successful. Carbonation in drinks adds to the irritation, alcohol has no effect. Rough solid food distracts the nerves with a different signal to the brain.

How do we rate chili peppers? The Scoville test for Capsaicinoids. Capsaicin is measured in parts per million and converted into Scoville heat units: 1 ppm = 15 Scoville heat units. The hottest peppers are the habaneros (200K - 300K Scoville Units), whereas the mildest are bell peppers (0 Scoville Units).

Research on chili peppers is ongoing. Healthwise, there is no evidence that chili peppers lead to ulcers. Instead, research sugggests that chilis may have health benefits. Capsaicin has been found to have anticoagulant properties. Chilis are high in vitamin C, as much or more than citrus fruits.  Some research is focused on the understanding pain pathways (and pain-killers) via the capsaicin receptor in the brain, which is in the "pain" pathway.