UV Sterilization Does Not Change Antibacterial Activity of Honey

Evaluation of the Shelf-Life of Canadian Active Honeys

Katrina Brudzynski and Jennie Kim
Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada, L2S 3A1

Abstract presented at: 5th German Apitherapy Congress, March 23-25, 2007, Passau, Germany

Honey is well recognized for its nutritional values, but honey’s proven antibacterial activity creates a basis for its medical use. The objective of this project was to establish a shelf-life of Canadian honey possessing antibacterial activity.

The antibacterial activities were analysed using a broth microdilution assay against two bacterial spp.: Gram-negative Escherichia coli (ATCC14948) and Gram-positive Bacillus subtilis (ATCC 6633).

Since antibacterial activity of Canadian honey depends on the concentration of hydrogen peroxide produced by honey, the levels of this compound were analyzed using peroxide/peroxidase assay in the parallel experiments.

The shelf-life of active honey was assessed by comparison of antibacterial activity during storage of honey (diluted 1:1 with sterile water) for 3 days in room temperature in a sterile environment. The storage reduced both antibacterial activity of honey and production of hydrogen peroxide.

In addition, storage of 50% honey solution encouraged the growth of osmophilic microbes naturally contaminating honey (bacteria, yeast, and moulds) as demonstrated by the standard plate count.

Introduction of sterilization of honey using a germicidal UV lamp prolonged its shelf-life beyond 13 days (further periods were not tested). More importantly, UV sterilization did not change antibacterial activity of honeys nor hydrogen peroxide production levels. In conclusion, honey possessing antibacterial activity and destined for therapeutic use must be sterilized. Moreover, UV irradiation of honey did not diminish either its antibacterial activity or the levels of hydrogen peroxide.