Qualitative and quantitative food authentication of oregano using NGS and NMR with chemometrics

Abstract

Culinary herbs and spices represent increasingly popular food products, especially in an environment of increased consciousness of food quality. Health-conscious consumers expect clean and reliable labels for food products. For spices this implies significant challenges considering complex and long supply chains, often with unknown sources or intermediates. A recent report by the EU Joint Research Centre identified oregano as one of the most vulnerable spices for adulterations. The analysis of herbs is complex, traditionally using visual inspection, and more recently genetic and chemical analysis. Here, metabarcoding by next generation sequencing (NGS) has been used to identify the nature of oregano products and possible adulterations. In parallel, metabolite extracts are generated and analysed on a 400 MHz Nuclear Magnetic Resonance (NMR) spectrometer. NMR metabolic profiles in conjunction with multivariate statistics was used to identify oregano species and to identify and quantify the level of adulteration with other plant products. • New analytical strategy for qualitative and quantitative authentication of oregano by combination of metabarcoding by NGS and metabolomics/chemometrics by NMR. • Unique biomarkers discovered in adulterants by NMR. • Metabolomic profiles obtained by NMR correlate well with oregano species and regional origin. • Quantification of the percentage of an adulterant with error rates of 3–7%. • Simultaneous quantification of two and more different adulterants in a specimen.