Constit. of many essential oils e.g. Citrus, Eucalyptus and Juniperus spp. Oil of Litsea ceylanica is a major source (20%). Flavouring agent The terpinenes are three isomeric hydrocarbons that are classified as terpenes. They each have the same molecular formula and carbon framework, but they differ in the position of carbon-carbon double bonds. alpha-Terpinene has been isolated from cardamom and marjoram oils, and from other natural sources. beta-Terpinene has no known natural source, but has been prepared synthetically from sabinene. gamma-Terpinene is natural and has been isolated from a variety of plant sources. (Wikipedia)

Alpha-Terpinene is Found in These Foods