New insights into the combined effects of geographical origin, cultivar and crop season on the physicochemical characteristics of Moroccan olive oils produced in northern Morocco. A comparative study

Abstract

The Tangier-Tetouan-Al Hoceima (TTA) region is one of the main olive oil producing regions in Morocco. Little is devoted to characterize olive oil physicochemical traits from TTA hence the originality of this study. This aimed at investigating variation in olive oil quality produced from three Moroccan cultivars ‘Moroccan Picholine’, ‘Menara’, and ‘Haouzia’ and their blends. Sampling was performed in five provinces fromTTA (Northern Morocco) during four consecutive crop-seasons (2018–2021) considering three extraction technologies (ET): traditional discontinuous press system (SP) and continuous extraction systems including decanter of three outlets (3O) and decanter of two outlets (2O). Physicochemical measurements consisted of routinely quality parameters namely free acidity (FA), peroxide value (PV), UV absorption parameters (K₂₃₂, K₂₇₀, and ΔK), chlorophylls (Chl) and carotenoids (Car) contents, total phenolic compounds (TPC) and oxidative stability (OS). Crop season showed its superiority impacts on K₂₃₂, OS, TPC, Chl, and OS. While cultivar was the main variability source in both PV and K₂₇₀, and FA was mainly determined by ET. Important variations (p ​< ​0.05) were reported among crop seasons and locations due to pedoclimatic differences. ‘Menara’ and ‘Haouzia’ had higher pigments content, TPC, and OS, and the blends displayed low pigments concentration, TPC, and OS. Expectedly, continuous ET (2O and 3O) had the greatest values of pigments content, TPC, and OS as revealed by principal component analysis. Strong correlations were highlighted among basic quality parameters, TPC, pigments, and OS. Simple linear regression was used to describe the relationships between OS and TPC (R² ​= ​0.856) and OS regressed against Chl (R² ​= ​0.690) and Car (R² ​= ​0.760), while TPC were regressed on Chl (R² ​= ​0.670) and Car (R² ​= ​0.680) and finally Chl against Car (R² ​= ​0.931). In conclusion, compared to technological, genotypic, and geographic effects, climatic conditions were the main factor driving olive oil stability and associated phenolics and pigments; oil cultivar blend seems to have negative effects on pigments concentration and total phenolic compounds as well as oxidative stability.