## 3 Results and Discussion
### Polar Phenolic Substances  
Polar phenolic compounds are key components for assessing the quality of an olive oil due to their contribution to sensory, healthy, and stability properties. Within these substances, great attention has been devoted in the last years to a sub-group of phenolics indicated as \"hydroxytyrosol and its derivatives like oleuropein complex and tyrosol\" [22], whose concentration, when exceeding \(250\;\mathrm{mg\;kg^{-1}}\) of oil, allows the acknowledgement of the health claim on olive oil polar phenolic compounds. To the best of our knowledge, the composition of polar phenolic compounds in the monovarietal oils from cvs. investigated in the present study, have never been reported earlier with the only exception of ASC, whose oils, obtained from crops cultivated in Tunisia, have been studied from this point of view [11]. Among the 79 oils investigated in the present study, 70 resulted in a  
Figure 1: Oleic acid percentage (**a**) and linoleic acid percentage (**b**) in total fatty acid composition in Ascolana tenera (ASC), Coroncina (COR), Mignola (MIG), Piantone di Mogliano (MOG), and Raggia (RAG) monovarietal oils investigated, which was produced in 2015 and 2016. Bars indicate \(\pm\) standard deviation. All different letters indicate significant differences (\(p<0.05\), One-way ANOVA, [PERSON]’s test for pairwise comparison) among the 10 oil sample groups investigated.  
composition that allows the acknowledgement of the mentioned health claim. Thus, this shows high quality from this point of view, similarly to what was found by [PERSON] et al. (2018). These authors reported that all the Italian EVOOs investigated (28 from protected designation of origin consortia and 256 from little family farms all over the Italian country) had levels allowing the acknowledgement of the health claim. The cultivar with the highest total polar phenolic compounds content (largely represented, from 89.2% to 95.0%, by the substances considered by the health claim) resulted in RAG having an average total concentration of \(434.2\pm 151.2\) mg kg\({}^{-1}\). The one with the lowest content was MOG with an average total concentration of \(318.3\pm 123.3\) mg kg\({}^{-1}\) (Table 1). In addition, the average content of the total phenolic substances considered by the above-mentioned health claim does not vary significantly between the cvs. investigated. In 2015, it varies from 255.7 \(\pm\) 112.5 mg kg\({}^{-1}\) found in MOG to \(443.4\pm 169.7\) mg kg\({}^{-1}\) found in RAG while, in 2016, from 346.0 \(\pm\) 104.8 mg kg\({}^{-1}\) in ASC to 395.7 \(\pm\) 130.5 mg kg\({}^{-1}\) in COR. However, in both years, RAG is one of the two cvs. with the highest content and MOG is one of the two with the lowest content. Considering the whole of the MEVOOs investigated, their average content of the phenolic substances considered by the health claim, is higher as compared to levels reported for EVOO blends commonly found in the large retail distribution market (supermarket) ([PERSON] et al., 2018; [PERSON] et al., 2018). Interesting information to fingerprint the different varieties were provided mostly by minor phenolics, like phenolic acids, lignans, and flavonoids, which seem to be more characteristic for the cvs. investigated as compared to the major phenolic substances (secoiridoid derivatives). Statistical analysis indicated that the content of acetoxypinoresinol was significantly higher in RAG (\(p\) = 4.4 10\({}^{-9}\) and 1.1 10\({}^{-7}\) in 2015 and 2016 samples, respectively) than in each of the other cvs. investigated in both years. The finding is in agreement with other studies pointing at lignans as possible varietal markers ([PERSON] et al., 2018). Regarding phenolic acids, MOG and MIG had the highest content of \(p\)-coumaric acid and vanillic acid, respectively, in both years.