In-Depth Two-Year Study of Phenolic Profile Variability among Olive Oils from Autochthonous and Mediterranean Varieties in Morocco, as Revealed by a LC-MS Chemometric Profiling Approach.

Aadil Bajoub,Lucía Olmo-García,Romina Monasterio,Santiago Medina-Rodríguez,El Ajal,Alberto Fernández-Gutiérrez,Hafida Hanine,Alegría Carrasco-Pancorbo

doi:10.3390/ijms18010052

Abstract

Olive oil phenolic fraction considerably contributes to the sensory quality and nutritional value of this foodstuff. Herein, the phenolic fraction of 203 olive oil samples extracted from fruits of four autochthonous Moroccan cultivars (“Picholine Marocaine”, “Dahbia”, “Haouzia” and “Menara”), and nine Mediterranean varieties recently introduced in Morocco (“Arbequina”, “Arbosana”, “Cornicabra”, “Frantoio”, “Hojiblanca”, “Koroneiki”, “Manzanilla”, “Picholine de Languedoc” and “Picual”), were explored over two consecutive crop seasons (2012/2013 and 2013/2014) by using liquid chromatography-mass spectrometry. A total of 32 phenolic compounds (and quinic acid), belonging to five chemical classes (secoiridoids, simple phenols, flavonoids, lignans and phenolic acids) were identified and quantified. Phenolic profiling revealed that the determined phenolic compounds showed variety-dependent levels, being, at the same time, significantly affected by the crop season. Moreover, based on the obtained phenolic composition and chemometric linear discriminant analysis, statistical models were obtained allowing a very satisfactory classification and prediction of the varietal origin of the studied oils.

Highlights

Virgin olive oil (VOO) is a quite popular and nutritionally important and valuable vegetable oil, which is widely produced in the Mediterranean Basin and areas with similar climatic conditions for human consumption, and with cosmetic and medicinal purposes [1]
Extensive research supports the high phenotypic and genetic variability of this cultivar in different Moroccan olive growing regions, suggesting that the name of “Picholine Marocaine” encompass a pool of various local genotypes [10,11]. This fact can complicate the olive orchard management when nutrients, irrigation and other agricultural practices must be applied to the cultivar demands and its agronomic characteristics. To cope with these constraints that can hinder the development of the olive oil sector in Morocco, and meet the current needs of Moroccan olive oil industry searching for more productive cultivars with specific traits, the National Institute of Agronomic Research has extensively worked on breeding programs, mainly based on clonal selection [12], cross-breeding [13], and comparative studies of agronomic and adaptive traits of some Mediterranean varieties recently introduced in Morocco [14]
We corroborated that the generation of artificial peaks in the chromatograms is not as serious as for oleuropein aglycone (Ol Agl) and ligstroside aglycone (Lig Agl) and could be even ignored

Summary

Introduction

Virgin olive oil (VOO) is a quite popular and nutritionally important and valuable vegetable oil, which is widely produced in the Mediterranean Basin and areas with similar climatic conditions for human consumption, and with cosmetic and medicinal purposes [1]. One of the main reasons is that olive cultivation in Morocco has traditionally been based on planting a single cultivar so-called “Picholine Marocaine” (occupying almost 90% of the total Moroccan olive cultivated area) [7] This autochthonous cultivar shows good adaptability to a wide range of Moroccan pedoclimatic conditions, and exhibits interesting agronomic traits, oil quality, and composition characteristics [8]; it presents some limitations, such as an accentuated alternate bearing [6] and susceptibility to the main olive fungal diseases, those caused by Spilocaea oleagina, Verticillium dahliae and Fusarium solani [9].

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