ginger - Chemistry
Picture of Ginger section
Ginger contains up to 3% of an essential oil that causes the fragrance of the spice. The main constituents are sesquiterpenoids with 
-zingiberene as the main component. Lesser amounts of other sesquiterpenoids (β-sesquiphellandrene, bisabolene and farnesene) and a small monoterpenoid fraction (β-phelladrene, cineol, and citral) have also been identified.
The pungent taste of ginger is due to nonvolatile phenylpropanoids (particularly gingerol and zingerone) and diarylheptanoids (gingeroles and shoagoles); the latter are more pungent and form from the former when ginger is dried. With a specific procedure is used for cooking, where ginger root acquires a soda form and transforms gingerol into zingerone, which is less pungent and has a spicy-sweet aroma. "harold"