3.2.1 Fatty acid profiles
The fatty acids of Coratina and Koroneiki in different age are presented in Table 2, and they are all in agreement with the EVOO standard. On the other side, there were significant differences between Coratina and Koroneiki in fatty acids, mainly in oleic acid, linoleic acid and stearic acid. Owing to the differences in the content of oleic acid and stearic acid, there was a gulf existing in the ratio of MUFA to PUFA (MUFA/PUFA) of Coratina and Koroneiki. Contents of other fatty acids were similar, so the ratio of UFA to SFA (UFA/SFA) was little difference in all the samples. Significant differences were also found in the same variety of different ages. As can be seen in Table 2, the percentages of major fatty acids in Coratina and Koroneiki oils varied irregularly according to tree age. The capricious fluctuation in fatty acid resulted in MUFA/PUFA and UFA/SFA in Coratina and Koroneiki oils showed a jumble variation with tree age.
There are plenty literature reports focusing on the effects of varieties on fatty acid profiles. In addition, previous reports have been demonstrated that geographical condition greatly affects the fatty acids of olive oils from the same cultivar. Compared with the Coratina oils around the world, the mean percentage of palmitic acid was in a high level, oleic acid was in a low level, and linoleic acid was in an intermediate level in Coratina oils in the present study (Aparicio & Luna, 2002; Bruscatto et al., 2017; Ceci, Mattar, & Carelli, 2017; Fuentes et al., 2018). Koroneiki was another widely planted olive variety in the world. In comparison with the Koroneiki oils from other regions, the mean percentage of palmitic acid was in a high level, oleic acid was an intermediate level, and linoleic acid was in a low level in the studied Koroneiki oils (Fuentes et al., 2018; Wang et al., 2018). Besides, the effects of tree age on fatty acid profiles were not exactly the same as the existing reports. Chtourou et al. have been concerned about the effects of olive trees age on fatty acid composition and found that the variations of fatty acid composition were not significant with respect to tree age (Chtourou et al., 2017b). However, tree age existed unclear effects on fatty acid compositions in this study.