Differentiation of Organically and Conventionally Grown Tomatoes by Chemometric Analysis of Combined Data from Proton Nuclear Magnetic Resonance and Mid-infrared Spectroscopy and Stable Isotope Analysis

• Published in: Journal of agricultural and food chemistry 2015-11, Vol.63 (43), p.9666-9675
• Main Authors: Hohmann, Monika, Monakhova, Yulia, Erich, Sarah, Christoph, Norbert, Wachter, Helmut, Holzgrabe, Ulrike
• Format: Article
• Language: English
• Subjects: Agriculture; Carbon Isotopes - analysis; Discriminant Analysis; Lycopersicon esculentum - chemistry; Lycopersicon esculentum - growth & development; Nitrogen Isotopes - analysis; Organic Agriculture; Oxygen Isotopes - analysis; Proton Magnetic Resonance Spectroscopy - methods; Spectrophotometry, Infrared - methods
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/acs.jafc.5b03853

Because the basic suitability of proton nuclear magnetic resonance spectroscopy (1H NMR) to differentiate organic versus conventional tomatoes was recently proven, the approach to optimize 1H NMR classification models (comprising overall 205 authentic tomato samples) by including additional data of isotope ratio mass spectrometry (IRMS, δ13C, δ15N, and δ18O) and mid-infrared (MIR) spectroscopy was assessed. Both individual and combined analytical methods (1H NMR + MIR, 1H NMR + IRMS, MIR + IRMS, and 1H NMR + MIR + IRMS) were examined using principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), linear discriminant analysis (LDA), and common components and specific weight analysis (ComDim). With regard to classification abilities, fused data of 1H NMR + MIR + IRMS yielded better validation results (ranging between 95.0 and 100.0%) than individual methods (1H NMR, 91.3–100%; MIR, 75.6–91.7%), suggesting that the combined examination of analytical profiles enhances authentication of organically produced tomatoes.