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.
We use 60-MHz benchtop nuclear magnetic resonance (NMR) to acquire 1 H spectra from argan oils of assured origin. We show that the low-field NMR spectrum of neat oil contains sufficient information to make estimates of compositional parameters and to inform on the presence of minor compounds. A screening method for quality and authenticity is presented based on nearestneighbour outlier detection. A variety of oil types are used to challenge the method. In a survey of retail-purchased oils, several instances of fraud were found.
Argan oil is obtained from the fruits of the Argan tree (Argania spinosa), an endemic species from south-western Morocco. Oil is extracted from Argan seeds through a traditional or a semi-automated process. In the case of edible oils, seeds are roasted before extraction, but when the oil is used for cosmetics, no seed roasting is required. Several cooperatives and private enterprises are established in south-west Morocco producing and commercializing edible and Cosmetic Argan oil. The identification of the geographical origin of Argan oils is attracting great interest from consumers and producers since it may be used as a criterion for guaranteeing quality and authenticity. Stable isotope techniques can provide useful information on the origin of food products. For these reasons the natural abundance isotopic ratios of Carbon, Oxygen and Nitrogen were measured using isotope ratio mass spectrometry (IRMS) for samples (cosmetics oil, seed) produced between July and August 2012 in different Moroccan cooperatives with certified PGI (protected geographical indication) label and organic certification, representing five provenances in the southwest part of Morocco. These provenances are distinct on a Geographical, hydrological and climatic level: Essaouira, Agadir Idaou Tanane, chtouka Ait Baha, Taroudant and Tiznit.IRMS was selected as a reliable technique to characterise the stable carbon and oxygen isotope 'fingerprints' of Moroccan Protected Geographical Indication (PGI) Argan oils and nitrogen isotope analysis of the Agan nut. Moreover, it demonstrated relationships between environmental parameters and the isotopic composition of plants coming from geographically distinct areas. The results obtained in this study indicate that it is possible to differentiate Argan oil producing areas, which can be associated with regional (cooperatives), and promote and protect the quality and commercial value of this important Moroccan plant product.
The Mediterranean diet is promoted as one of the healthiest and closely linked to socioecological practices, knowledge and traditions, promoting sustainable food production, and linking geographical origin with food quality and ecosystem services. Consumer adherence to this dietary pattern drives increased consumption of authentic "premium" foods, such as Iberian pig meat and dry-cured ham from Portugal and Spain, argan oil from Morocco, "Djebel" lamb from Tunisia and truffles from Italy and Slovenia, i.e., food products that respond to current ethical, environmental and socially sustainable demands. Geographical indication and appellation of origin can increase traditional food products competitiveness, but the high-value recognition of these products can also lead to economically motivated product adulteration. It is therefore imperative to protect the high added value of these unique food products by ensuring their quality, authenticity, provenance and sustainable production systems. In this review, we provide a critical evaluation of the analytical methods that are currently used for the determination of provenance and authenticity of these Mediterranean products as well as possible strategies for improving the throughput and affordability of the methods discussed.
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