Classification of the geographical origin of argan kernels by infrared spectroscopy and chemometrics

Abstract

The main objective of this study is the use of Fourier transform mid-infrared (FTIR) spectroscopy for discrimination of samples of Argan kernels from three Moroccan regions. The content of Argan oil extracted from the kernel depends on the plant genotype and on the environmental conditions. The origin of argan kernel samples could be distinguished combining the IR spectra measurement and chemometric tools for discriminant analysis. A multivariate analysis procedure based on the combined use of Hierarchical Cluster Analysis (HCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) was tested for this purpose. HCA showed three distinct clusters related to the Moroccan regions and suggested the usefulness of IR spectroscopy to distinguish among kernel origins. Afterwards, PLS-DA was used for the discrimination and classification of the origin of the various argan kernels and good classification models and validation results were obtained. For 9 new unknown samples we attribuate 100% these samples by external validation. The results demonstrated that the combined use of FTIR and chemometric analysis (cluster analysis and discrimination by PLS- DA) can be used to rapidly and simply determine the origine of argan kernels, a relevant task for the agroalimentary Moroccan industry.