Determinant factors of olive oil stability, phenolic content and antioxidant capacity

Abstract

Purpose This study aims to identify the effect of selected agro-industrial factors associated with the olive oil phenolic composition, total phenolic content (TPC), antioxidant capacity and oxidative stability index (OSI). The study also aims to assess the relationship between the quality indices and each of the individual phenol, TPC, antioxidant capacity and OSI. Design/methodology/approach Olive oil samples (n=108) were collected from Lebanese northern (Akkar and Zgharta-Koura) and southern (Hasbaya and Jezzine) regions, at three harvesting times (early, intermediate, late) and using different types of mills (traditional, sinolea, two- and three-phase decanters). The samples were analyzed using official standard methods. Findings The highest TPC, antioxidant capacity and OSI were obtained in early harvested olive oil, using two-phase decanters for TPC and three-phase decanters for antioxidant capacity and OSI. A prediction model, including the free acidity, K232, TPC, C18:2, C18:0, tyrosol and apigenin, was obtained; it allowed to predict very highly significantly the OSI (p < 0.001). Apigenin, tyrosol and C18:2 recorded the highest standardized coefficients (ß^+= 0.35) and thus had the highest influence on OSI. As per antioxidant capacity of olive oil, another very highly statistically significant prediction model was constructed (p < 0.001). It included only two predictors, oleacein and TPC, with the latter having the most influence (ß^+= 0.37). Originality/value The overall results highlighted the detrimental effects of agro-industrial factors on olive oil chemical composition, and this contributes significantly to improve olive oil’s quality and characteristics, which are important for the product economical and nutritional values.