Capsaicin is a personal favourite molecule of mine. This little compound is responsible for the spiciness in chillies. Spiciness is actually rated according to the Scoville scale – a unit based rating system for assessing the spiciness of food. Pure capsaicin has a rating of up to 16,000,000 scoville units. The world’s hottest chilli, the Naga Jolokia pepper can be in excess of 1,000,000 scovilles. Tabasco sauce averages around 40,000 scovilles and jalapeños can be as low as 2,500.
Chemically, capsaicin is a fairly ordinary compound. Odourless, colourless, crystalline to waxy, hydrophobic… For the interesting part, I have to go all biological for a while. Capsaicin is interesting because of the way it acts. The molecule affects the same nerve endings in your skin that warn your body of heat and abrasive damage, which is why the spiciness of chillis is usually described as a “burning sensation”. Of course, there’s no real damage of any kind going on, your body just thinks it’s being burned and responds as it would to a genuine burn. This is why strong chillies can cause redness and inflamation of the skin, as well as a few of the body’s natural defense responses like sweating, elevated heart rate and a mild adrenaline rush.
Incidentally, capsaicin is also not soluble in water, so if you’ve eaten something too spicy for you, drinking water won’t do much. Ice water will give you temporary relief, but not much. Capsaicin is most soluble in oils (lipids) though, so milkshakes or yoghurt drinks (like lassi) will help cool your tastebuds. Certain types of fleshy fruit (like pear and mango) also contain enough fatty acids to help alleviate the burn. Also (and although it seems like a horrible thing to do), rinsing your hands with oil before washing them with soap and water is a great way to clean the spice off your fingers.
Interestingly, as well as being the source of beautiful spiciness in foods, capsaicin has a vast wealth of other uses. Many people consider chillis to be an aphrodisiac (culturally, peri peri has a reputation for lifting the mood and heightening the senses). Capsaicin itself has a range of medical uses including, bizarrely, as a topical painkiller. The effect on the nerves apparently prevents them from registering other pain for a while. Chillis, as well as several other spices including turmeric, have been shown in studies to inhibit certain types of cancer. Circumstatial evidence has been known for years – in countries where lots of spicy food is eaten, cancers of the mouth, throat and gastrointestinal tract are much less frequent. One study (done right here in Nottingham) showed how capsaicin can cause apoptosis (cell death) in lung cancers. Generally, spicy food is shown to increase blood flow and assist poor circulation too.
Eat your curry, kids. It’s good for you!