NMR Metabolite Profiling in the Quality and Authentication Assessment of Greek Honey—Exploitation of STOCSY for Markers Identification

Abstract

Honey is a natural, healthy commodity and is probably among the most complex foods produced by nature. It is the oldest recorded and certainly the only natural sweetener that can be used by humans without any further processing. Nowadays, the increase in honey’s value, along with its growing list of healthy attributes, has made the present raw material a prime target for adulteration. In the current study, NMR-based metabolite profiling in combination with chemometrics was applied in the quality control of Greek honeys from northeastern Aegean islands. Moreover, statistical total correlation spectroscopy (STOCSY) was employed for the first time as a dereplication and structural elucidation tool in the honey biomarker identification process. A total of 10 compounds were successfully identified in honey total extracts via 1 H NMR spectroscopy. Compounds such as 5-(hydroxymethyl)furfural, methyl syringate, a mono-substituted glycerol derivative and 3-hydroxy-4-phenyl-2-butanone, among others, were identified as potential biomarkers related to the botanical and geographical origin of the samples. High-Resolution Mass Spectrometry (HRMS) was used as an additional verification tool on the identified compounds.

NMR-Based Metabolite Profiling and the Application of STOCSY toward the Quality and Authentication Assessment of European EVOOs

“…Even if it is used in human metabolomics [ 32 ], its employment in food analysis and generally in natural products is limited. To our knowledge, it has been used in the study of medicinal plants [ 44 , 45 , 46 , 47 ], whisky [ 48 ], and table olives and honey samples from our group [ 33 , 34 ].…”

“…One dimensional STOCSY analysis by exploiting the data with the 0.001 ppm bin size was carried out with an in-house routine in the MATLAB suite [ 33 , 34 ]. A threshold of 0.75 for the correlation coefficient was set on the whole dataset and it was kept at the same level for all generated pseudo-spectra.…”

“…Chemometrics were then employed for the identification of certain marker compounds. STOCSY, a strong statistical tool, was used for the first time in EVOO analysis to aid in the identification process [ 33 , 34 ]. Additionally, two Greek cultivars, Koroneiki and Kolovi, obtained directly from producers, were also examined for the first time with 1 H NMR metabolite profiling.…”

Insight into the Recent Application of Chemometrics in Quality Analysis and Characterization of Bee Honey during Processing and Storage

“…Honey freshness based on 5-HMF can be determined with several analytical protocols, however, an easy determination is executed using the 1 H NMR spectroscopy, where the integration of signals occurs at 4.65 ppm for the methyl protons or at 9.55 ppm for the proton of aldehyde, enabling its quantification [227].…”

Review on NMR as a tool to analyse natural products extract directly: Molecular structure elucidation and biological activity analysis

“…37 Similar application of STOCSY in food quality control were also reported. 38,39 In the identification of antiplasmodial triterpenes from Keetia species using NMR-based metabolic profiling, STOCSY was employed. 40 Targeted orthogonal partial least square (OPLS) signals In the metabolite differences between young Hypericum perforatum plants grown under different lighting conditions were also aided by STOCY.…”