Comparative study of phenolic compounds in olive oils from different geographic regions

© 2022, Turkiye Klinikleri. All rights reserved.In this study, the effect of cultivar, harvest year, and the geographic regions (Mediterranean, Aegean, Southeastern Anatolia, Marmara, and the Black Sea) on phenolic compounds of virgin olive oils were investigated. Tyrosol was the major phenolic compound in the Mediterranean, Southeastern, and Black Sea regions. Hydroxytyrosol showed the highest value (2.07 mg/kg) in the Southeastern Anatolia region and the lowest value (0.75 mg/kg) in the Marmara region. Among the phenolic acids, vanillic acid had an important place in phenolic compounds (p < 0.01). This phenolic acid gave higher values in the Marmara region compared to other regions. Flavonoids were determined as important groups of phenolic compounds in olive oils. The oils from the Southeastern Anatolia region separated from other oils with the highest levels of flavonoids such as quercetin, luteolin, and apigenin. All phenolic compounds, except transcinnamic acid and quercetin, increased in the second harvest year. Vanillic acid was the highest phenolic compound in the first year, in contrast, tyrosol had higher values than vanillic acid in the second year. Many phenolic compounds were affected by olive cultivar. Memecik has a higher content of tyrosol, vanillic acid, p-coumaric acid, ferulic acid, and quercetin in the Aegean region. However, this variety showed higher values for hydroxytyrosol, transcinnamic acid, luteolin, and apigenin in the Marmara region. Gemlik, Ayvalık, Çelebi, Domat and Memecik from Marmara regions had higher vanillic acid. Butko, Otur and Kızıl Satı showed higher tyrosol. Principal component analysis showed that phenolic compounds could play an important role in the separation of regions and cultivars.