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. 2024 Feb 7;13(4):516.
doi: 10.3390/foods13040516.

Detection of Adulterated Oregano Samples Using Untargeted Headspace-Gas Chromatography-Ion Mobility Spectrometry Analysis

Blas Rocamora-Rivera  1 , Natalia Arroyo-Manzanares  1 , Pilar Viñas  1
Affiliations

Detection of Adulterated Oregano Samples Using Untargeted Headspace-Gas Chromatography-Ion Mobility Spectrometry Analysis

Blas Rocamora-Rivera et al. Foods. .

Abstract

Oregano is often adulterated for economic reasons. This fraud mainly consists of adding other species with lower commercial value, such as olive leaves. To ensure the authenticity of oregano, an analytical method based on the analysis of the volatile organic compound (VOC) profile obtained by headspace gas chromatography coupled to ion mobility spectrometry (HS-GC-IMS) was developed and validated. Samples of ecological Mediterranean oregano adulterated with different percentages of two types of olive leaves (cornicabra and manzanilla) were studied using a non-targeted analysis. Moreover, a total of 30 VOCs were identified in the analyzed samples, and 24 compounds could be quantified using calibration curves based on Boltzmann's equation. A chemometric model based on orthogonal partial least squares discriminant analysis (OPLS-DA) was used to detect the adulterated oregano samples, obtaining a 100% validation success rate, and partial least squares (PLS) analysis was used to quantify the percentage of adulterant. Finally, the proposed methodology was applied to 15 commercial oregano samples, resulting in two of them being classified as adulterated with 31 and 43% of olive leaves, respectively.

Keywords: adulteration; gas chromatography; headspace; ion mobility spectrometry; oregano.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Summary of the proposed methodology.
Figure 2
Figure 2
Ecological oregano spectrum obtained with the optimized HS-GC-IMS method.
Figure 3
Figure 3
Signal distribution of compounds identified in oregano and olive leaves. This spectrum was the result of analyzing a mixed solution of all identified volatiles with a concentration of 10 µg g−1 in all cases except for carvacrol and thymol, which were measured at 1000 µg g−1. Protonated monomer and proton-bound dimer signals of each compound are inside a black rectangle. The unselected signals were produced by refined oil.
Figure 4
Figure 4
Score-plot of the selected OPLS-DA model.
See this image and copyright information in PMC

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