Green chili peppers are now in season. They are particularly strong and potent. You don't even have to eat one to experience how hot these peppers are. The chemical gases within the peppers are released the minute you cut them open and it makes you start coughing violently and forces you to temporarily vacate the kitchen.
"The substances that give chili peppers their intensity when ingested or applied topically are capsaicin (8-methyl-N-vanillyl-6-nonenamide) and several related chemicals, collectively called capsaicinoids. Capsaicin is the primary ingredient in the pepper spray used as an irritant weapon.
When consumed, capsaicinoids bind with pain receptors in the mouth and throat that are responsible for sensing heat. Once activated by the capsaicinoids, these receptors send a message to the brain that the person has consumed something hot. The brain responds to the burning sensation by raising the heart rate, increasing perspiration and release of endorphins.
The "heat" of chili peppers was historically measured in Scoville heat units (SHU), which is a measure of how much a chili extract must be diluted in sugar syrup before its heat becomes undetectable to a panel of tasters. Bell peppers rank at 0 SHU, New Mexico green chilis at about 1,500 SHU, jalapeños at 2,500–5,000 SHU, and habaneros at 300,000 SHU. The modern commonplace method for quantitative analysis of SHU rating uses high-performance liquid chromatography to directly measure the capsaicinoid content of a chili pepper variety. Pure capsaicin is a hydrophobic, colorless, odorless, and crystalline-to-waxy solid at room temperature, and measures 16,000,000 SHU.
World's hottest chili pepper - current record holder
According to Guinness World Records, as of February 25, 2011, the world's hottest chili pepper is the Naga Viper with a Scoville rating of 1,382,118 SHU. It may soon be replaced as the hottest by the "Trinidad Scorpion Butch T" chili, a 2.5 cm (1 inch) long chilli grown in Australia, that weighs in at 1,463,700 SHU."