Fourier transform infrared (FTIR) spectroscopy approach combined with discriminant analysis and prediction model for crude palm oil authentication of different geographical and temporal origins

Abstract

The traceability of palm oil to determine its geographical origins within the palm oil supply chains is of importance to ensure quality and sustainable production. The current traceability systems are insufficient, thus requiring a more viable and effective approach to improve the traceability framework of the palm oil supply chain. In this study, the feasibility of Fourier transform infrared (FTIR) and chemometric methods for the traceability of crude palm oil (CPO) samples in Malaysia was investigated. The orthogonal partial least squares-discriminant analysis (OPLS-DA) was used to examine the FTIR spectral data of 354 CPO samples collected from four different mills in Malaysia from February until July 2019. The optimal OPLS-DA models were achieved with standard normal variate (SNV) preprocessing and Pareto (Par) scaling to discriminate the CPO according to its geographical provenance and time of sampling. OPLS-DA models using CPO fingerprints successfully discriminated CPO samples according to their geographical origin and production month, with a total accuracy of correct classification for the blind samples (test set) in the prediction models greater than 90% and with the area under the receiver operating characteristic (ROC) curve values exceeding 0.9. The OPLS-DA loading plot indicated that spectral regions associated with free fatty acid (FFA), iodine value (IV) as well as the saturated and unsaturated fatty acid content were responsible for the discrimination patterns and can be potentially used as spectral markers to differentiate CPO samples. Overall, the study shows that combination of FTIR fingerprinting and chemometric methods could serve as an effective tool to trace and discriminating CPO samples according to their geographical origins and production times. The approaches used in the study present an innovative strategy for monitoring quality of palm oil, and moving forward will also facilitate efforts at successful tracking of palm oil across supply chains, especially when combined with additional analytical techniques.