Effect of thermal liquefying of crystallised honeys on their antibacterial activities

Thermal liquefying of crystallised honey is the most convenient option for beekeepers to fully liquefy honey. A controlled mild thermal treatment is widely used for effective and safe liquefying of crystallised honey. In this study, we demonstrated that thermal liquefying at different temperatures of 45, 55 and 65 °C does not affect the overall honey antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus, and, in some cases, it may even increase the antibacterial potential of honey. A mild thermal treatment of crystallised honey was able to significantly increase its glucose oxidase (GOX) enzyme activity. On the other hand, the increased GOX activity in treated honey samples did not affect levels of accumulated H2O2, suggesting that some phytochemicals may contribute to or modulate antibacterial activity. Taken together, a mild thermal liquefaction of crystallised honey may increase the potential bioactivity of this matrix, which is also affected by the botanical origin.