The effect of nisin A and sodium benzoate on behavior of Listeria monosytogenes and some microbial and chemical parameters in silver carp (Hypophtalmichtys molitrix) fillet stored at 4°C

The effect of nisin A and sodium benzoate on Listeria monocytogenes, as well as some microbial (mesophilic, psychrotrophic and lactic acid bacteria) and chemical (peroxide and TVN) in silver carp (Hypophtalmichtys molitrix) fillet during storage period (0, 3, 6, 9 and 12 days) at 4°C were evaluated. For this, Listeria monocytogenes (4 logCFU/g) was inoculated to the fillets and were dipped into 2% sodium benzoate solution for 15 min and left to stand for 10 min at 4°C. Subsequently nisin A was added to the fillet (0/15 g/kg) and samples were kept at 4°C while packaged in vacuum condition. The results showed that, application of nisin A and sodium benzoate decrease the number of Listeria monocytogenes from 4/12 to 3/66. However, in control groups the number of bacterium was increased from 4/43 to 5/14.Moreover, the number of mesophilic bacteria in treatment and control groups was increased from 4/39 to 6/79 and 4/48 to 7/93, respectively. The number of psychrotrophic bacteria in treatment and control groups was increased from 4/16 to 6/72 and 4/34 to 7/92, respectively. The similar result was achieved for lactic acid bacteria in which the number of these bacteria was increased from 2/74 to4/08 and 2/9 to 4/78, respectively. Moreover, different peroxide value and TVN for treatment and control groups was achieved. In conclusion, application of nisin A and sodium benzoate showed different inhibitory effects on Listeria monocytogenes in culture media and silver carp.