The sterilization of honey with cobalt 60 gamma radiation: a study of honey spiked with spores of Clostridium botulinum and Bacillus subtilis.

Unprocessed honey is a recognized wound-healing remedy. However, to make clinical use of honey acceptable, it should be sterile. To find the lowest dose of irradiation needed for sterilization, six batches of honey (a-f) were gamma irradiated with 6, 12, 18, 22 and 25 kGy Cobalt-60. After a dose of 25 kGy the antibacterial activity was not altered. Presumably glucose oxidase (EC 1.1.3.4), which produces hydrogen peroxide, is not easily damaged by irradiation. Amylase activity on the other hand was significantly reduced to 19%, 19%, 21%, 22%, 43% in batches a), b), c), d) and f) respectively, whereas no decrease was observed in batch e). All batches spiked with approximately 10(6) spores from Cl. botulinum or B. subtilis per 50 g honey proved to be sterile after irradiation with a dose of 25 kGy. Honey was also spiked with Cl. botulinum at up to 5000 spores per 50 g honey, which is the upper limit of natural contamination. The sterilizing dose in this case was 18 kGy.