Chilli facts and other useful studies.   The humble chilli pepper Chillies are the fruits from the capsicum plant and relatives of the tomato in the nightshade family (Solanaceae) Capsaicin  is the active chemical that causes the heat in a chilli pepper. Their heat is measured in "Scolville units" - so named after Wilbur Scolville, who developed the test in 1912 whilst working for the Parke Davis pharmaceutical company. The test involved diluting ground chilli with sugar and water solutions, the idea was that the chilli should be diluted until the liquid no longer burned the mouth. A number would then be assigned to this on the basis of how much dilution was needed to kill the heat. This testing has been widely criticised for its accuracy and validity, leaving pungency to be calculated by other methods, however these tests are still often related back to the Scolville unit.   Some example measurements                      Orange Habanero     300,000 Scolville Units                                                                                  Red Habanero          150,000 Scolville Units                                                                                  Tabasco                     120,000 Scolville Units                                                                                  Thai Hot                       60,000 Scolville Units Dealing with the heat How many times have you or your friends dived for the water jug or beer glass whilst munching an especially hot dish? - Did it help? Have you ever wondered why Mexicans and Indians serve butters and creams with their dishes? It's all down to ionic chemical reactions on the mouths pain receptors, called the polymodal nociceptors. Dairy products are able to neutralise the burning effect of the capsacin on these receptors. Of course a by-product of this is adrenaline, triggered by the brains response to the pain and responsible for many of the other side effects felt - Increased body temp, increased heart rate - that feeling of fight or flight. Handling chilli Peppers One golden piece of  advice here, always wear gloves when handing and preparing chillies, capsaicin is an extremely pungent substance and easy absorbed by the skin, this can be extremely painful if transferred to an eye or other sensitive area. The pith or placenta of the chilli is the most potent part - Not the seeds as many may think. Most cut it away, just using the clean flesh of the fruit in their cooking. However theres no reason not to throw it in for a little extra kick!