Sensorial and microbial effects of gaseous ozone on fresh

摘要

The bactericidal activity of gaseous ozonewas investigated using a commercial ozone generator. Five species of fish bacteria,Pseudomonas putida, Shewanella putrefaciens, Brochothrix thermosphacta, Enterobacter sp.and Lactobacillus plantarum, were inoculated on agar surfaces and exposed todifferent ozonation times in a gas chamber. Results showed ozone in relatively lowconcentrations ( 0·27 10 3 g l 1) was an effective bactericide of vegetativecells of the five fish bacteria. The age of the cell culture was shown to influence the cellresponse following exposure. Survival rate was not linearly related to ozonationtime, but exhibited biphasic death over an extended period. Similar bactericidal effectswere observed on fish skin treated with ozone daily in the laboratory, withdecreases of 1·0 log cfu cm 2 for the micro-organisms studied. Whole fish treated dailyin the laboratory using a commercial ozone generator showed improved scoresfor sensory analyses compared with the controls. The results were statisticallysignificant. Fish treated on board ships were also analysed for microbiological and sensorychanges. Controls were obtained from a similar vessel without the ozone facility in thehold. Similar trends to those recorded in the laboratory for the microbiological and sensoryresults on ozonated fish were observed.