Chemical characterization of oils produced by some native and introduced genotypes of argan tree in eastern Morocco using HPLC-DAD/GC-MS, and the evaluation of their physicochemical parameters

Abstract

The argan tree is an endemic plant of Morocco that plays a great socio-economical and ecological impact in the south of the country. This plant is well known for the oil extracted from the almond, characterized by high nutritional value and its large spectrum of uses. This study aims to evaluate the chemical composition and the physicochemical parameters of fixed oils produced by the argan trees introduced in Oujda City and to compare them with other oils produced by the same trees in their natural biotope in the northeast and southwest of Morocco. The obtained results indicated that the oil yield varies between 57.65% and 47.60%. The investigation of the chemical composition using HPLC-DAD showed the presence of three types of tocopherols: α-tocopherols (9.7%), δ-tocopherols (6.6%), and γ-tocopherols (83.6%), the total content of tocopherols vary between 323.86 and 553.12 mg/kg. While, the methyl esters analysis using GC-MS showed the presence of 4 main fatty acids: oleic acid (55.40–41.14%), linoleic acid (36.92–26.75%), palmitic acid (18.69–9.97%) and stearic acid (12.09–3.68). The physicochemical parameters (the free acidity, the peroxide value, and the specific extinction) indicated that the different tested oils are characterized by a good oil quality according to the Moroccan standard concerning argan oil (NM 08.5.090). The obtained results indicated that the introduced argan in Oujda City showed a quality and a chemical composition that was comparable to that produced in the natural area of the argan tree, which shows the plasticity the plant under different climatic and edaphic conditions. These results emphasize the encouragement of the introduction of this species at a high level in eastern Morocco.