Study of authenticity, quality characteristics and bioactivity in honey samples from different botanical origins and countries

Honey is a widely consumed commodity featuring beneficial nutritional properties resulting in a high market price. Therefore, honey is a target of fraudulent practices and analytical strategies to assess honey quality and origin are highly needed. Within this context, we performed a comprehensive analytical testing for 39 honey samples originating from Greece and other countries. Analytical parameters related to honey quality control (Directive 2001/110/EC) were monitored. In detail, hydroxymethylfurfural (HMF) and diastase activity were measured using spectrophotometric assays. Importantly, 6 samples imported by the American market exceeded the regulatory limit (40 mg/kg). The content of the main honey sugars was monitored using an accredited ultra-high-performance liquid chromatography coupled to evaporative light scattering detector (UHPLC-ELSD) and all samples were in line with the regulatory standards. In addition, chromatographic analysis was performed to determine 23 phenolic compounds as these are bioactive compounds contributing towards the health promoting effects of honey. Besides chemical characterisation, in vitro testing was also performed by monitoring the inhibitory effect of the honey samples towards acetylcholinesterase (AChE) and pancreatic lipase (PNLIP). Indeed, inhibition was noticed and in the case of PNLIP the monitored differences between Greek and samples from other countries were statistically significant. To assess honey sample authenticity, chemometric tools were employed, namely, principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA). The multivariate analysis revealed that the taxifolin content may be used as a marker for thyme honey from Cyprus while the total content of gallic and protocatechuic acids could be used as a marker for oak honeys. All in all, implementing several different methods based on different principles (both physicochemical and bioanalytical) in a complex analytical matrix such as honey is a great analytical challenge that we successfully faced and comprehensively demonstrated in this study.