GROWTH RESPONSE OF VIBRIO PARAHAEMOLYTICUS AND LISTERIA MONOCYTOGENES IN SALTED FISH FILLETS AS AFFECTED BY ZATARIA MULTIFLORA BOISS. ESSENTIAL OIL, NISIN, AND THEIR COMBINATION

The growth of Vibrio parahaemolyticus (at inoculation levels, 103 and 105 cfu/g) and Listeria monocytogenes (at inoculation level, 103 cfu/g) were investigated in salted fish fillets (brine salted at 4% NaCl) as affected by different concentrations of Zataria multiflora Boiss. essential oil (EO), nisin (N) and their combinations at 8C (and 4C only for L. monocytogenes) during 21 days. The growth of V. parahaemolyticus was inhibited at 8C (in control group) and reached <2 log10 cfu/g at the first day of study for inoculation level of 103 cfu/g. At inoculation level of 105 cfu/g, this inhibitory effect was significantly (P < 0.05) affected by adding EO. The significant inhibitory effect of N alone and synergistic inhibitory effect of EO with N were also observed during the study. For L. monocytogenes, the obvious significant inhibitory effect of EO and its combination with N was observed at 4C. Considering the organoleptic effect of the EO used in this study, the best inhibitory effects of EO in combination with N for V. parahaemolyticus and L. monocytogenes were obtained at combinations of EO = 0.405% and n = 0.75 mu g/mL, and EO = 0.405% and n = 0.25 mu g/mL, respectively. PRACTICAL APPLICATION The synergistic inhibitory effect of Zataria multiflora Boiss. essential oil and nisin on V. parahaemolyticus and L. monocytogenes, which was obtained in this study can improve the scope of essential oil function in food industry.