The physico-chemical characteristics of peel essential oils of sweet with to times and isolation methods

Within the scope of this study, essential oil content and its quality parameters of Batem Fatihi, Navelina, Washington Navel, Valencia Late, and Moro cultivars were evaluated with respect to harvest time and isolation methods. Essential oils were obtained using two methods (hydrodistillation and cold pressing) during four harvest periods of each cultivar. Physico-chemical characteristics of essential oils were evaluated, and the chemical components of the oil were identified via GC-MS/FID. Based on the hydrodistillation data, the essential oil ratios ranged between 1.69-2.85 % in samples. While the effects of cultivar and harvesting time on relative density, refractive index, and optical activity values were not statistically important, the effect of isolation method was important (p < 0.05). Relative densities of essential oils obtained by cold pressing were higher (0.8440) than those obtained by hydrodistillation (0.8402). Additionally, refractive index values of the samples obtained by cold pressing were higher (1.4739) than those obtained by the hydrodistillation method (1.4723). On the other hand, it was observed that the optical activity values of the samples obtained by hydrodistillation were higher (98.20 degrees) than those obtained by cold pressing (95.32 degrees). Chromatographic analysis indicated the presence of 10 compounds in the essential oil. Essential oil compositions also showed some differences on the basis of cultivars, harvesting time, and isolation methods, but these differences generally were not statistically significant. Additionally, there were some differences in determined components with respect to cultivar, harvesting time, and isolation method. The most important component in all analyzed samples was determined to be limonene and it was distributed between 94.9-96.4%. The second highest component was determined as beta-myrcene and ranged between 1.9-2.0%. While the effect of isolation method and harvesting time on limonene was not important (p > 0.05), the effect of cultivar was significantly important (p < 0.05). On the other hand, both cultivar and harvesting time effects on beta-myrcene content were significantly important. Our results showed that there is a significant variation in some quality parameters of the orange peel essential oils according to cultivar and isolation methods.