Fatty Acid Composition of Cosmetic Argan Oil: Provenience and Authenticity Criteria.

Milena Bučar Miklavčič,Fouad Taous,Lidija Strojnik,Nives Ogrinc,Vasilij Valenčič,Tibari Elghali,Maja Podgornik

doi:10.3390/molecules25184080

Abstract

In this work, fatty-acid profiles, including trans fatty acids, in combination with chemometric tools, were applied as a determinant of purity (i.e., adulteration) and provenance (i.e., geographical origin) of cosmetic grade argan oil collected from different regions of Morocco in 2017. The fatty acid profiles obtained by gas chromatography (GC) showed that oleic acid (C18:1) is the most abundant fatty acid, followed by linoleic acid (C18:2) and palmitic acid (C16:0). The content of trans-oleic and trans-linoleic isomers was between 0.02% and 0.03%, while trans-linolenic isomers were between 0.06% and 0.09%. Discriminant analysis (DA) and orthogonal projection to latent structure—discriminant analysis (OPLS-DA) were performed to discriminate between argan oils from Essaouira, Taroudant, Tiznit, Chtouka-Aït Baha and Sidi Ifni. The correct classification rate was highest for argan oil from the Chtouka-Aït Baha province (90.0%) and the lowest for oils from the Sidi Ifni province (14.3%), with an overall correct classification rate of 51.6%. Pairwise comparison using OPLS-DA could predictably differentiate (≥0.92) between the geographical regions with the levels of stearic (C18:0) and arachidic (C20:0) fatty acids accounting for most of the variance. This study shows the feasibility of implementing authenticity criteria for argan oils by including limit values for trans-fatty acids and the ability to discern provenance using fatty acid profiling.

Highlights

Argan oil is produced from the kernels of the argan tree (Argania spinosa (L.) Skeels) that is common to Morocco and parts of Algeria
Results on fatty acid composition together with the acidity and other relevant geoenvironmental parameters are collected in Tables S1 and S2
The fatty acid profile, combined with multivariate analysis, such as Discriminant analysis (DA) and orthogonal projection to latent structure—discriminant analysis (OPLS-DA), was evaluated and used to classify argan oil samples according to its geographical origin

Summary

Introduction

Argan oil is produced from the kernels of the argan tree (Argania spinosa (L.) Skeels) that is common to Morocco and parts of Algeria. As a multi-purpose tree, it plays a vital socioeconomic role, and its sustainable exploitation is essential in maintaining an ecological balance and preserving biodiversity [1]. The argan tree is the only representative species of the tropical family Sapotaceae in Morocco, it is the second-largest forest species after oak and before cedar and has a life span of 200 years or more. It is grown mainly in the arid and semi-arid regions of southwestern Morocco covering about 870,000 ha. The estimated twenty million trees are spread over the provinces of Essaouira (130,000 ha), Agadir-Ida ou Tanane (37,000 ha), Chtouka-Aït Baha (90,000 ha), Tiznit (140,000 ha), Taroudant (360,000 ha) and Inzeguane-Aït Melloul (13,000 ha), representing just about 17% of the original Moroccan forest area.

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Conclusion