The storage life of four species of fish from the North West Shelf was examined by means of nucleotide catabolism and sensory evaluation. It was found that the shelf life was related to the rate of inosine monophosphate (IMP) breakdown rather than to bacterial spoilage, because the endemic mesophilic bacteria were unable to adapt to ice storage conditions. The results indicated that the IMP level was fundamentally related to both flavor intensity, and acceptability, and was not merely circumstantially related to time of storage.

The relative effects of microbial and nonmicrobial spoilage on the shelf-life of yellow-eyed mullet were studied. Results of sensory and chemical analyses of sterile flesh stored at 4°C were compared with fillets which had either spoiled naturally while held at 4°C or frozen fillets held at -18°C. Inosine was produced rapidly in both treatments at 4"C, followed in sterile flesh by a slower breakdown to hypoxanthine. Hypoxanthine production from inosine was rapid in the presence of bacteria. Within 6 days sensory changes were observed in the frozen flesh and after 69 days, it was considered unacceptable. The development of off-odors and off-flavors in the absence of bacteria was not sufficiently slow to result in a significant extension in shelflife for this species.

The effect of solar radiation on the survival of Escherichia coli, Salmonella zanzibar and a faecal Streptococcus strain in seawater was tested in laboratory experiments, and survival of E. coli was tested under natural light conditions at Davis Station, Antarctica. Exposure to artificial light of wavelengths 290–800 nm caused a rapid decline in viability of each strain examined. T90 values (the time taken for 90% of the population to be inactivated) were ~50 min, 40 min and 2 h for E. coli, S. zanzibar and the faecal Streptococcus respectively. Selective removal of UV-B wavelengths of (<320 nm) increased survival of E. coli and S. zanzibar, resulting in T90 values of ~2.5 h. Screening out wavelengths of <370 nm (UV-B and most of UV-A) increased T90 values to 5 h for E. coli and 10 h for S. zanzibar. The visible band of the spectrum (400–800 nm) also had deterimental effects on faecal bacteria, when compared with survival in the absence of light. Rates of decline for E. coli in natural light in Antarctica were similar to those from laboratory experiments. However, resuscitation of sub-lethally damaged cells under optimum conditions resulted in greater recovery rates than were observed after exposure to artificial sunlight. Faecal bacteria were rapidly inactivated when exposed to sunlight in Antarctic waters, and as repair mechanisms are unlikely to operate under in situ conditions, resuscitation of sub-lethally damaged cells is improbable.

Combinations of potassium sorbate and polyphosphate, in conjunction with vacuum or modified atmosphere packaging, were assessed for their preservative effects on morwong fillets (pH 6.75) stored at 4°C. Vacuum packaged and/or frozen fillets were used as comparisons for microbiological and taste panel analysis. A combination of potassium sorbate, polyphosphate and 100% CO2 was the most effective packaging regime. Potassium sorbate on vacuum packaged fish was more effective than a 100% CO2 atmosphere alone. Polyphosphate had no apparent additional effect on fillets stored under vacuum with or without potassium sorbate.