Extraction methods and geographical variability influence on phenolic content, fatty acid composition and physicochemical quality, of Moroccan Picholine olive oils in the Fes-Meknes region

Abstract

The study aims was to analyze the influence of extraction method and geographical origin on the quality of olive oils. Thirty samples of the "Moroccan Picholine" variety were collected from three types of crushers (hydraulic press, two-phase and three-phase) in four cities of the main Moroccan olive-growing region, Fes-Meknes, during the 2021 and 2022 harvest seasons. Oils from this region are generally of virgin and extra virgin olive oils quality, according to the International Olive Council, with high levels of oleic acid reaching up to 80.12 ± 1.94% for oils produced in Meknes, two-phase triturations. Two-phase extracted oils from Fez and Meknes show the highest MUFA/PUFA (monounsaturated fatty acids/ polyunsaturated fatty acids) ratios and lower quality parameters, indicating richness in monounsaturated fatty acids and improved oxidative stability. Polyphenol levels varied significantly between the cities of Fez, Meknes, Taounate and Taza, reaching 307.31 ± 17.44 mg/kg GAE for Fez, with notable differences ( p < 0.05). In addition, chlorophyll and carotenoid levels differed significantly according to the type of extraction and the city of origin ( p = 0.004 and p = 0.042, respectively). Principal component analysis identified three distinct groups based on extraction method and geographical location, highlighting the importance of these factors in obtaining olive oils with the specific characteristics sought.