EFFECT OF MICROWAVE RADIATION ON MICROORGANISMS IN FISH MEALS

This study was aimed at testing the effect of microwave radiation on survival of E. coli, Salmonella Enteritidis, Enterococcus spp. and Clostridium spores in two kinds of fish meals. The material used in the study consisted of samples of two kinds of fish meal - salmon and cod. In the experiment samples of both kinds of fish meals were inoculated with suspensions of tested bacteria and spores of Clostridum sporogenes. After inoculation the material was exposed to microwave radiation with a frequency of 2.45 GHz and microwave energy power of 0, 100, 180, 300, 450, 600 and 700 W, respectively, for 2.5 min for bacteria and 11 minutes for spores. Then the reisolated microorganisms were counted and theoretical lethal doses of radiation were determined. Among the studied vegetative forms of bacteria, the largest decreases in the numbers at the same radiation dose were observed in the rods of E. coli, whereas the smallest in enterococci. Spores of Clostridium sporogenes showed a considerably higher resistance to the effect of that factor. The power of dose resulting in the complete inactivation of the studied bacteria should be about 430 kJxg(-1), and in the case of spores - 1 900 kJxg(-1).