Authentication of strawberry tree (Arbutus unedo L.) honeys from southern Europe based on compositional parameters and biological activities

Abstract

Strawberry-tree (Arbutus unedo L.) honey is expensive and difficult to characterize by melissopalinology. This study aimed to authenticate strawberry-tree (A. unedo L.) honeys from southern Europe, determining arbutin, groups of polyphenols, volatile and semivolatile compounds, as well as biological activities such as trolox equivalent antioxidant capacity, antioxidant activities against both hydroxyl (AOA) and superoxide radicals (SRS), oxygen radical absorbance capacity, anti-inflammatory activity, and antimicrobial activity against 7 microorganisms (Escherichia coli, Streptococcus mutans, Staphylococcus aureus, Aspergillus flavus, Aspergillus niger, Fusarium sp., and Penicillium commune). Arbutin, analyzed using HPLC-UV, was quantified in 83% of the samples. Polyphenols' contents were high. Norisoprenoids and benzene derivatives were the major compounds determined using gas chromatography-mass spectrometry. Theobromine was detected in 67% of samples. 2,6,6-Trimetyl-4-oxo-2-cyclohexen-1-carboxaldehyde, 3,4,5 trimethylphenol and 2-hydroxycyclopent-2-en-1-one were proposed as potential strawberry-tree floral markers. Antioxidant and anti-inflammatory activities were significant. Honeys’ extracts showed higher AOA and SRS, and better antimicrobial activities than the honeys. This study highlights the potential of strawberry-tree honeys and/or their phenolic extracts for food, pharmaceutical and cosmetic uses.