A Multi-Isotopic Chemometric Approach for Tracing Hazelnut Origins

Abstract

High-value products, such as hazelnuts, are particularly vulnerable to fraud due to their price dependence on geographical origin. Guaranteeing hazelnuts' authenticity is essential for consumer trust and safety. Stable isotope analysis has become a reference method for origin authentication as it is reliable, robust, and easily transferable across laboratories. However, multiple isotopic markers coupled with chemometric techniques are often needed to authenticate food provenance accurately. In this study, we focused on assessing the potential of bulk δ¹⁸O, along with δ²H and δ¹³C of the main fatty acids, as hazelnut-origin authenticity markers. PLS-DA classification models were developed to differentiate samples (n = 207) according to their region of origin. This multi-isotopic approach provided promising external validation results, achieving a 94% global correct classification rate in discriminating hazelnuts from regions with distinct geographical and environmental conditions. This study lays the groundwork for further model development and evaluation across additional production areas and harvest years.

Keywords: PLS-DA; food fraud; geographical authentication; hazelnut; stable isotopes.

Figure 1

Score plot of the first and second principal components of the PCA model developed using bulk δ¹⁸O data and δ²H, δ¹³C data of the main fatty acid methyl esters.

Figure 2

Score plot of the first and second latent variables of the PLS-DA model developed using bulk δ¹⁸O data and δ²H, δ¹³C data of the main fatty acid methyl esters.