DNA technology for food authentication is already well established, and with the advent of Next Generation Sequencing (NGS) and, more specifically, metabarcoding, compositional analysis of food at the molecular level has rapidly gained popularity. This has led to several reports in the media about the presence of foreign, non-declared species in several food commodities. As herbs and spices are attractive targets for fraudulent manipulation, a combination of digital PCR and metabarcoding by NGS was employed to check the purity of 285 oregano samples taken from the European market. By using novel primers and analytical approaches, it was possible to detect and quantify both adulterants and contaminants in these samples. The results highlight the high potential of NGS for compositional analysis, although its quantitative information (read count percentages) is unreliable, and other techniques are therefore needed to complement the sequencing information for assessing authenticity (‘true to the name’) of food ingredients.

Lievens, A., Paracchini, V., Garlant, L., Pietretti, D., Maquet, A. and Ulberth, F., Detection and Quantification of Botanical Impurities in Commercial Oregano (Origanum vulgare) Using Metabarcoding and Digital PCR, FOODS, ISSN 2304-8158, 12 (16), 2023, p. 2998

Consumers and companies associated with food or pharmaceuticals rely on spices and herbs in various forms. Their intricate supply chains, elevated prices, and low-volume production render them vulnerable to fraudulent practices. However, comprehensive methodologies to detect adulterants remain scarce, impeding national control laboratories from enforcing European and national legislation. In this study, we present quantitative real-time PCR (qPCR) methods designed to identify the top five adulterants of each of six commonly consumed spices and herbs: paprika/chili, turmeric, saffron, cumin, oregano and black pepper. The specificity of each method was confirmed by qPCR analysis of a large collection of relevant plant species. Each authentic sample was combined with its respective top five adulterants as identified in the European Union-wide coordinated control plan on herbs and spices in 2021 or in the existing literature. These binary mixtures were used to evaluate the method's performance with respect to sensitivity, linearity and trueness at four levels of adulterants concentration. Detection was also investigated in multi-adulterated samples. These SYBR™ Green-based qPCR methods enable the specific detection of adulterants, and their sensitivity allows for the distinction between inadvertent contamination and deliberate adulteration. Altogether, these methods contribute to safeguard the authenticity of these high-value commodities

Behr, M., Garlant, L., Pietretti, D., Pellegrin, C., Lievens, A., Boix Sanfeliu, A., Maquet, A. and Alvarellos Lopez, L., A robust set of qPCR methods to evaluate adulteration in major spices and herbs, FOOD CONTROL, ISSN 0956-7135, 165, 2024, p. 110623

Oregano is frequently adulterated as demonstrated in a recent control plan organised by the European Commission. In this work, the elemental profiles of 282 oregano samples analysed by energy dispersive X-ray fluorescence were used in combination with multivariate analyses to detect adulteration, in particular with olive leaves. The analyses were carried out in the frame of the coordinated control plan on the authenticity of herbs and spices organised by the European Commission. Partial Least Square Discriminant Analyses, allowed the detection of adulterated samples with a sensitivity of 81 %, and a specificity of 92 %; among the adulterated samples PLS-DA allowed the detection of samples that contained olive leaves with a sensitivity of 94 % and a specificity of 92 %. Copper mass fraction is of relevance because it is significantly higher in samples adulterated with olive leaves. The ratio Cu/Zn allowed the identification of adulterated samples with a sensitivity and specificity of 85 % without the need to use modelling techniques. The elemental profile of oregano obtained by EDXRF was also used to authenticate the geographical origin declared in the labels.

PAPOCI, S. and DE LA CALLE GUNTINAS, M.B., Use of energy dispersive X-ray fluorescence as screening method to detect oregano adulteration, CURRENT RESEARCH IN FOOD SCIENCE, 10, 2025, p. 101099,

Multi-elemental analyses using ED-XRF have proven their efficacy in food authentication, but sample intake can be a drawback in the analysis of expensive matrices such as saffron. In this work, small sample holders and the double pellet method (a thin sample layer on a wax pellet) were combined to determine 19 elements of interest in food analysis, using only 1 gram of sample. The trueness of these two approaches was evaluated with 17 different organic matrix reference materials of (lichen, wheat flour, rice flour, bran, brown bread, cabbage, vegetable feed, pine needles, and spinach, tomato and tobacco leaves). Double pellets provided accurate results (recovery 100%) for Mg, Al, Si, P, Cl, S, K, Ca, Cr, Mn and Fe, but the penetration of the radiation into the wax layer of the double pellet hindered quantitative recovery for heavier elements. Contrarily, small sample holders were less accurate for the very light elements (Mg, Al and Si) but the recovery was satisfactory (> 80%) for the remaining ones, including the heavier elements (Cu, Zn, Rb, Sr, Cd and Ba). Ni and Br determinations were affected by a possible matrix dependent interference. The method was validated to analyse 21 Iranian saffron samples collected on the EU market.

Ghidotti, M., Papoci, S. and De La Calle Guntinas, M.B., Validation of an Energy Dispersive X-Ray Fluorescence method for small sample intake in a wide range of matrices. Application to the analysis of saffron, SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY, ISSN 0584-8547, 189, 2022, p. 106369