Characterization and Comparison of Extra Virgin Olive Oils of Turkish Olive Cultivars

Abstract

Extra virgin olive oils (EVOOs) obtained from five Turkish olive cultivars widely produced in the Aegean and Marmara regions were investigated based on their total antioxidant capacity (TAC), total phenolic content (TPC), pigment contents, fatty acid (FA) profiles, phenolic compounds (PC), volatile compounds (VC), and sensory properties. The results showed that all properties of EVOO samples were significantly affected by the olive cultivar used. The pigment contents in Ayvalık (9.90 mg·kg−1) and Uslu (9.00 mg·kg−1) oils were higher than the others (p < 0.05). The greatest values for oleic acid (74.13%) and TPC (350.6 mg·kg−1) were observed in Gemlik and Domat oils, respectively (p < 0.05). Edincik oil showed the maximum hydroxytyrosol content (48.022 mg·kg−1) and TAC value (515.36 mg TE·kg−1) (p < 0.05). The Edincik, Domat, and Uslu oils were significantly not different for the total content of C6 compounds derived by lipoxygenase, which are the main volatiles responsible for the typical aroma of EVOOs (p > 0.05). Domat oil also exhibited the highest scores for bitterness and pungency perceptions (p < 0.05). The fruitiness scores of the oil samples (except for Ayvalık oil) were close to each other, even if they were statistically different (p < 0.05). Principal component analysis (PCA) indicated that the Ayvalık oil was separated from the others due to its poor-quality characteristics. As a result, it can be stated that Domat olive oil has better quality than the others.

Discrimination of Turkish Gemlik virgin olive oils by growing regions and environmental conditions

“…This clearly explains the difference between HPLC results and TPC results at Table 4. Our results are consistent with TPCs in Turkish olive oils ranging between 12 and 990 mg/kg of oil, as reported by (Keceli, 2013a; 2013b; Arslan & Ok, 2020; Korkmaz, 2023; Uluata et al, 2021).…”

“…A daily dose of 2–15 mg of hydroxytyrosol or oleuropein‐related compounds is required for health claims made by EFSA (European Commission, 2012). Our findings are consistent with the hydroxtyrosol and tyrosol contents of Turkish cultivars (Al‐Juhaimi et al, 2017; Arslan & Ozcan, 2011; Korkmaz, 2023; Uluata et al, 2021) and some Spanish and Tunisian cultivars reported by (El‐Gharbi et al, 2018; Polari et al, 2021). On the other hand, changes in environmental conditions (increase in temperature and relative humidity and decrease in rainfall see Table 1) may have increased both tyrosol and p‐coumaric acid levels significantly in Gemlik virgin olive oils in 2017 harvest year (Table 4).…”

“…This finding is consistent with those of (Hmida et al, 2022;Špika et al, 2021) who reported that a decrease in oleic acid and an increase in the levels of stearic, palmitic acid and linoleic acid in olive oil extracted from high temperature and less rainy areas. Gemlik virgin olive oils fatty acid composition is consistent with that described by other authors for Turkish olive varieties such as Gemlik (Arslan & Ok, 2020;Keceli, 2013b;Korkmaz, 2023;Özcan et al, 2019;Sevim et al, 2023;Uluata et al, 2021) and some Tunisian and Spanish olives (El-Gharbi et al, 2018;Hannachi et al, 2013;Hmida et al, 2022;Polari et al, 2021).…”

“…Thus, phenolic compounds in the oils obtained from low altitude and high temperature areas (Izmir and Mersin NPDO) is higher than in oils obtained from high altitude and low temperature area (Bursa PDO) which is consistent with findings of (Hmida et al, 2022; Mailer et al, 2010). The total phenol value determined by spectrophotometer lower than the sum of the individual phenol compounds obtained by HPLC (Dugo et al, 2020; Korkmaz, 2023). This clearly explains the difference between HPLC results and TPC results at Table 4.…”

Investigating the Quality and Purity Profiles of Olive Oils from Diverse Regions in Selçuk, İzmir

“…As seen in Table 2, the coumaric acid content of the KK group was found to be significantly higher than the other groups (p < 0.05). Similar to these results, Korkmaz [34] reported that regional differences in phenolics of different varieties from olive oils obtained from different regions of Turkey appeared to be distinctive in PCA analysis. ES samples were clustered in a different position from the other sample groups in the score plot, with PC2 in the positive and PC1 in the negative part of the score plot.…”