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Influence of ozone on shelf-life and quality of silvergrey rockfish (Sebastes brevispinis)

University of British Columbia

Ozone treatments of the chilled water surrounding fish during storage affects microbial and sensory properties of the stored product. In the first part of the study a better understanding of the effect of ozone on the microbial and sensory properties of freshly caught Silvergrey Rockfish (SebasLes brevispinis) was obtained. In the second part of the study, a method to quantify the inactivation of various typical fishspoilage microorganisms by ozone was developed. A survey examining the unloading process of fishing boats indicated that the unloading process did not contribute to an increase in microorganisms on the skin of tested fish samples. Sensory properties of the fish were not significantly improved by ozone treatment during an experiment simulating storage conditions on British Columbia fishing boats. The only significant difference (p<O.O5) due to ozonation was the reduction of the trimethylamine (TMA) level in the fish meat which, however, did not manifest in the sensory properties of the fish meat. Ozonation also did not cause any apparent colour differences in the fish meat. Although the number of skin microorganisms was initially reduced, after day 3 the microbial population on the ozone treated fish increased. Gill samples from ozone treated fish showed consistently higher, but not significantly different (except for one day), levels of microorganisms than the control samples. A model disinfection study was adequate to estimate the sensitivity of various typical fish spoilage microorganisms to ozone under strictly defined conditions. Of the bacterial strains tested Pseudomonas tragi was the most sensitive followed by Alteromonas putrefaci ens and Alteromonas punctata subsp. punctata. Staphylococcus aureus was the least sensitive to inactivation by ozone.

Thesis/Dissertation

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2009-03-04

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http://hdl.handle.net/2429/5496

Food Science

University of British Columbia

UBCV

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