Gingerol, properly as -gingerol, is the active constituent of fresh ginger. Chemically, gingerol is a relative of capsaicin and piperine, the compounds which give chilli peppers and black pepper their respective spicyness. It is normally found as a pungent yellow oil, but also can form a low-melting crystalline solid. Cooking ginger transforms gingerol via a reverse aldol reaction into zingerone, which is less pungent and has a spicy-sweet aroma. When ginger is dried or mildly heated,[further explanation needed] gingerol undergoes a dehydration reaction forming shogaols, which are about twice as pungent as gingerol. This explains why dried ginger is more pungent than fresh ginger. Ginger also contains 8-gingerol, 10-gingerol, and 12-gingerol, collectively deemed Gingerols.