Bacterial Flora of Frozen Fish

The bacterial flora was investigated on 25 frozen fish samples, consisting of 6 frozer raw fish and 19 frozen packed fish products.Enumeration and isolation of bacteria was conducted with smear plate method using 50% sea water agar medium.When 342 isolates were identified biologically, 33.9% were Flabobacterium-Cytophaga, 33.3% Moraxella, 9.1% Staphylococcus, 8.5% Micrococcus, 3.8% gram-positive rods, 2.6% Acinetobacter, and 2.3% Pseudomonas I/II.Effect of frozen storage process on the viability of the organisms of the nine groups, including Pseudomonas I, II, III/IV-H, III/IV-NH, Vibrio, Moraxella, Micrococcus and Staphylococcus was compared using the cell suspension in 10% skim milk medium. The result obtained showed that the organisms of Pseudomonas III/IV-H, III/IV-NH and Vibrio died off much more rapidly than those of the remaining 6 groups did.Changes in bacterial flora of minced fish and squid sample caused by frozen storage for 43 days were observed. Pseudomonas I/II, III/IV-H, III/IV-NH and Vibrio which had been found before freezing disappeared after frozen storage. Conversely, Moraxella, Flavobacterium-Cytophaga, Micrococcus and Staphylococcus dominated after frozen storage.From the results described above, it was revealed that the domination of Flavobacterium-Cytophaga, Moraxella, and coccus groups in the frozen fish samples is attributed mainly to rapid death of Pseudomonas and Vibrio in frozen storage, compared with the above-mentioned groups.