Assessing the Content of Phytochemicals in Honey Samples: Polyphenols as Bio-Indicators of Their Botanical Origin ^†

Abstract

Honey is a natural food product well known for its high nutritional value. Apart from sugars, it contains phytochemicals, including polyphenols and flavonoids, that are compounds with highly demonstrated antimicrobial and antioxidant capacities. The main goal of this work is the development of an analytical methodology to obtain the polyphenolic profile of honeys from different varieties and pollen sources. To isolate the target compounds from the samples, miniaturized vortex (VE) and ultrasound-assisted extraction (UAE) employing aqueous solvent followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) were employed. The results revealed that more than 20 different polyphenols were detected in the analyzed samples among the 40-targeted compounds, reaching total concentrations up to hundreds of µg g⁻¹. Other indexes such as the total polyphenolic content (TPC) and antioxidant activity (AA) were also evaluated by spectrophotometric techniques. ANOVA and PCA based on the results from TPC, AA and individual polyphenol concentrations showed that significant differences appeared depending on the honey variety, being several of the identified polyphenols, especially hydroxycinnamic acids, responsible for the main differentiation. The results also revealed that two components were enough to explain more than 90% of variance and honey classification in six different groups. Having regard to the occurence and concentrations of individual polyphenols, it is shown that the combination of chromatographic analysis, mass spectrometry detection and PCA are suitable tools to investigate the botanical authentication of honey.