The physico-chemical characteristics of peel essential oils of mandarin cultivars grown in Türkiye

Essential oil (EO) content and its quality parameters of seven mandarin cultivars were evaluated with respect to harvest time and isolation methods. EOs were obtained by hydrodistillation (HD) and cold pressing (CP) methods. EO components of the oil were identified by gas chromatography-mass spectrometry (GC-MS/FID). The EO content ranged between 1.12-2.76% in samples. While the effect of isolation method on relative density, refractive index, and optical acitivity values was statistically important, the effect of cultivar was important (p < 0.05) on refractive index and optical activity. The relative density of EOs obtained by CP (0.8440) was higher than that obtained by HD (0.8402). The refractive index value of the samples obtained by CP (1.4739) was higher than HD method (1.4723). On the other hand, the optical activity value of the samples obtained by HD (98.20°) was higher than CP (95.32°). Refractive index and optical activity value ranged between 1.4734 (Batem Göral)-1.4741 (Nova) and 77.38 (Yerli Apireno)-96.13 (Batem Göral) according to cultivars. EO components and their contents also showed some differences on the basis of cultivars, harvesting times and isolation methods, but these differences generally were not statistically significant. The most important component was determined to be limonene, and it ranged between 76.6% (Yerli Apireno) and 96.2% (Nova). While the effect of isolation method and harvesting time on limonene were not statistically significant (p > 0.05), the effect of cultivar was significantly important (p < 0.05). The second highest component was determined as β-myrcene and ranged between 1.9 and 2.1%. Cultivar and harvest time effects on β-myrcene content were statistically significant. Another important component was γ-terpinene for Batem İncisi (4.6%), Batem Yıldızı (4.4%), and Yerli Apireno (13.7%). Results showed that there were significant variations in composition and some quality parameters of the mandarin peel EOs according to cultivar and isolation methods. The research findings indicated that the essential oil obtained from the Yerli Apireno was in compliance with international standards for limonene and γ-terpinene content. However, the Batem Göral, Clementine Fina, Nova, and Fortune cultivars, which have a high limonene content, were found to stand out in this regard.