AS SEEN ON MASTERCHEF AUSTRALIA! Mastic gum is principally used either as a flavouring or for its gum properties. As a spice, it continues to be used in Greece to flavour spirits and liquors, chewing gum and a number of cakes, pastries and desserts. The flavour can be described as a strong slightly smoky, resiny aroma and can be an acquired taste. The resin is harvested from the mastic trees grown in the Greek island of Chios. Originally liquid, it is sun dried into drops of hard, brittle, translucent resin. Mastic resin is a spice that has been used, principally, as a chewing gum, for at least 2,400 years.