The physicochemical, polyphenol, antioxidant and antibacterial properties of Maltese honey

Abstract

Since ancient times, Maltese honey has been highly prized for its aromatic flavour and medicinal properties, so much so that Malta was commonly nicknamed as "the land of honey". Apart from its flavour, nutritional and calorific value, honey has a long legacy of use in traditional medicine and a strong backing from modern scientific research. Despite its fine medicinal reputation, no coherent studies on the antimicrobial properties of Maltese honey have yet been published. The objective of this study was to give a first insight on the antibacterial properties of Maltese honey and present a point of departure for potential future production of medical grade honey of local origin. Honey samples (n=12) of varying type (monofloral and multifloral), floral origin, harvesting season and location were randomly collected to provide an elementary representation of Maltese honey. The antibacterial analysis was complimented with physicochemical, total polyphenol and antioxidant activity determination. Antimicrobial activity was investigated using the broth macro-dilution method (CLSI, 2012). The mean minimum inhibitory concentrations (MIC) on three bacteria; Escherichia co/i ATCC® 25922, Staphylococcus aureus ATCC® 259213 and Pseudomonas aeruginosa ATCC® 27853, were found to 0.18 g/ml ± 0.07, 0.12 g/ml ± 0.05 and 0.15 g/ml ± 0.06 respectively and MIC values ranged 0.031 to 0.25 g/ml. Statistical analyses revealed that there is a significant difference between spring and autumn honey derived from difference in free acidity, total polyphenols, colour, HMF content, conductivity, DPPH antioxidant strength and antibacterial properties against 5. aureus. There was no statistical difference between seasons in the other parameters tested. Antimicrobial properties against 5. aureus correlated with colour, total phenolic content and antioxidant strength while MIC results for P. aeuroginosa correlated with total phenolic content. Maltese honey is high in total phenolic content, has antioxidant properties and is a good antibacterial agent. Thus, such results signify that more research is required to determine the source of antimicrobial strength in specific types of Maltese honey.