Quality profile of Chios mastic (mastiha) essential oil

Mastic oil is the essential oil of mastic (mastiha), the resin of Pistacia lentiscus L. var. chia Duham (Anacardiaceae), uniquely produced in the Greek island of Chios. It is a valuable product with a small annual yield (˜300kg), as well as mastic itself. Its characteristic odor and its established beneficial activities [1,2,3,4] have created an increased demand in cosmetics industry, leading to a high purchasing price (>€2,500/kg) and an adulteration danger. Therefore, the determination of mastic oil quality profile, considering the factors that potentially contribute to it (resin origin, storage time), could be used to afford an unambiguously labeled product. For this purpose, several mastic oil samples of different local origin, as well as different resin and oil storage time were analyzed with chiral GC-MS in order to set content limits for its compounds. Locality has little influence in the proportions, while mastic storage time before distillation clearly affects them, as the differences in the major compounds' contents show (α-pinene increases from 69.7% for samples distilled 2 months after harvest to 78.9% after 9 months, and myrcene decreases from 19.5% to 11.1%, respectively). The effect of mastic oil storage time was smaller (differences of <3% within 1 year), but the analysis of a 40-year-old sample revealed a dramatic drop in myrcene content, appointing it as the most characteristic criterion of mastic oil aging. Content limits for all mastic oil compounds were determined, within which a mastic oil sample should lay in order to be characterized as authentic and non-aged.