Taous, F., Amenzou, N., Marah, H., Maia, R., Máguas, C., Bahmad, L. & Kelly, S. (2020) Stable isotope ratio analysis as a new tool to trace the geographical origin of Argan oils in Morocco.Forensic Chemistry, 17, 100198. DOI:10.1016/j.forc.2019.100198 (IF2020 2,676; Q3 Chemistry, Analytical)
Argan oil is obtained from the fruits of the Argan tree (Arganiaspinosa), 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.