Applicability of high‐resolution NMR in combination with chemometrics for the compositional analysis and quality control of spices and plant‐derived condiments

Abstract

Over the last years, the consumption of spices and plant‐derived condiments has increased considerably, owing to new culinary trends. Unfortunately, the current marketing channels make them highly vulnerable to adulteration and food fraud. High‐resolution nuclear magnetic resonance (NMR) is a powerful tool for the compositional study of spices and plant‐derived condiments. It allows the chemical characterization of a wide range of polar and non‐polar metabolites, and provides unique structural information not available by other techniques. The chemometric‐based analysis of NMR ‘fingerprints’ has been used to discriminate samples according to species and geographical origin and to detect adulterations, among other applications. The comprehensive identification and quantification of marker compounds can be achieved even in complex mixtures, demonstrating a great potential for high‐throughtput quality control applications. © 2020 Society of Chemical Industry

Metabolite Fingerprinting Using 1H-NMR Spectroscopy and Chemometrics for Classification of Three Curcuma Species from Different Origins

“…Sample preparation was carried out according to Kim et al [22] with modifications. An amount of 5 mg extract was weighed and placed into a 2 mL microtube.…”

“…Moreover, NMR spectroscopy can be used for simultaneous analysis either primary or secondary metabolites comprehensively in certain samples [19,20]. Combined with chemometrics of multivariate analysis such as principal component analysis (PCA), partial least square-discriminant analysis (PLS-DA), and orthogonal projections to latent structures-discriminant analysis (OPLS-DA) which can manage the huge data generated from NMR measurement, it becomes a powerful analytical tool for metabolite fingerprinting of medicinal plants [21,22]. Combination of 1 H-NMR spectroscopy and chemometrics of PLS-DA and OPLS-DA has been used for authentication of Saffron adulteration [23].…”

Graphical exploration of 600‐ and 60‐MHz proton NMR spectral datasets from ground roast coffee extracts

“…The presence of canephora in a blend is betrayed by its aftertaste, described as ‘peanutty’, 23 although the limit of detection even by trained sensory experts is around 15% w/w. Analytical tests developed using NMR can perform substantially better than this, 24–27 down to detection limits commensurate with ‘adventitious contamination’ 28,29 : very low amounts of adulteration arising from some kind of mistake during transport or processing rather than deliberate fraud.…”

“…The presence of canephora in a blend is betrayed by its aftertaste, described as 'peanutty', 23 although the limit of detection even by trained sensory experts is around 15% w/w. Analytical tests developed using NMR can perform substantially better than this, [24][25][26][27] down to detection limits commensurate with 'adventitious contamination' 28,29 : very low amounts of adulteration arising from some kind of mistake during transport or processing rather than deliberate fraud. Spectra of complex biological samples such as coffee invariably contain large numbers of peaks, typically in the hundreds, and the dynamic range of the spectral intensities is such that the largest resonances dwarf the smallest by orders of magnitude.…”

Non-Targeted NMR Method to Assess the Authenticity of Saffron and Trace the Agronomic Practices Applied for Its Production

“…Further reported studies explored the application of alternative analytical methods to ascertain the presence of contaminants in saffron under the threshold value of 20% through the use of MALDI mass spectrometry [21], diffuse reflectance infrared Fourier transform spectroscopy [22], Raman spectroscopy [23], and electronic nose [24]. In this context, NMR spectroscopy coupled with chemometric analysis has been reported as a suitable approach for the quality assessment and authentication of this precious spice, being able to detect a wide range of adulterants, from synthetic dyes to herbal materials [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. However, to date, no official NMR analytical protocol is available to detect levels of contaminants in saffron below the threshold level of 20 wt%.…”