Effects of irradiation, antimicrobial agents and modified-atmosphere packaging on histamine production by Morganella morganii in mackerel fillets

The effects of gamma irradiation (0.5 and 2.0 kGy), antimicrobial agents (5 % sodium chloride and 1 % potassium sorbate) and modified atmosphere (100 % CO₂) packaging (MAP) on histamine production by Morganella morganii were examined in mackerel fillets during 8 days of cold storage. MAP combined with antimicrobial agents was also applied to the fillets. The changes in histamine levels, M. morganii and total aerobic bacterial counts were determined during the storage. All methods used in this study showed beneficial effect in controlling bacterial growth and histamine production on mackerel fillets during 2-3 days of storage. MAP combined with 5 % sodium chloride has more retarding effect on production of histamine than the other methods. For M. morganii, maximum inhibition effect was found at the dose of 2.0 kGy. Irradiation with a dose of 2.0 kGy, MAP combined with sodium chloride and MAP were also found to have the most inhibiting effects on total aerobic bacterial count during the storage.