Changes in Pistachios Essential Oil Composition during Fruit Ripening

Abstract

Pistacia vera is an agricultural product cultivated in semi-arid regions worldwide. Iran is the major cultivator, producing approximately 230 000 metric tons annually. Some studies have shown that the pistachio hull is rich in volatiles. The essential oil (EO) content and composition of pistachio skin were studied at different fruit ripening stages. The quantity and quality of the EO samples were studied at three different fruit ripening stages including green-hull, green-red hull and red hull. The oil was extracted by the hydro-distillation method and analyzed using GC/MS. Hydro-distillation of each sample resulted in diverse amounts of colorless essential oil lighter than water. Oil yield was the lowest (0.33 %) at the green stage and increased significantly (p < 0.01) reaching the maximum values of 0.67 % at the red stage. Depending on the developmental stage of the plant, different compounds were detected and qualitative variations in the chemical compound categories were observed during fruit ripening. However, familiar monoterpenes, such as α-terpinolene, α-pinene, limonene, α-bornyl acetate, Δ-3-carene, etc., were the most dominantconstituents in all stages. In conclusion, the fruit developmental stage significantly (p < 0.01) affect the EO content of pistachio, and change the major EO components. The appearance of the mentioned EO constituents can be considered as the main factors for the scented smell of each cultivar and their presence in pistachio hulls could aid in protection against pests and herbivores. As well as, this aids to produce plant material with the promising required oil composition to meet the specific needs of active pharmaceutical ingredients.