Irradiation as a process in eliminating pathogens in Ghanaian smoked tuna

The hygienic quality of Ghanaian smoked tuna was determined microbiologically by examining samples obtained from the local market. Escherichia coli was present in 30% of the samples examined; Staphylococcus aureus was prevalent in 80% of the samples. The microorganisms present were predominantly bacteria, moulds and yeasts occurring occasionally in low concentrations. Freshly smoked tuna were irradiated at doses 0, 1.0, 2.0, 3.0, and 4.0 kGy and subjected to organoleptic evaluation for the colour, taste and texture. The mean scores for colour, taste and texture were beyond the borderline for acceptability. The doses applied did not cause any significant change in the organoleptic quality of smoked tuna. Smoked tuna of low and high salt concentrations were irradiated at the doses 0, 1.0, 2.0, 3.0, and 4.0 kGy. One batch of the treated fish was stored in a refrigerator (5-10 deg. C) and the other at ambient (25-28 deg. C). They were examined at intervals for organoleptic and microbiological quality. The shelf-life of smoked tuna with low salt content was extended by 3 days when irradiated at 3.0 kGy and that of high salt content for 6 days. Cold storage delayed spoilage and products were in good condition for more than 12 days of storage. A number of packaging materials were evaluated for the packaging of irradiated smoked tuna. Paper and vacuum sealed polythene were found to be better. Irradiated smoked tuna was transported to Kumasi (250 km), analysed and the results compared to that of a batch kept in the laboratory. Transportation was found not to affect the irradiated packaged fish significantly. (author). 20 refs, 5 figs, 8 tabs