Individual and combined effects of nisin-Z and sodium citrate on the chemical attributes and lactic acid, mesophyll and psychrophill bacteria communities of Caspian Kutum fillets (Rutilus frisii kutum) Stored at 4 ºC

Individual and combined effectsof Nisin Z (1.5%) and sodium citrate (2%) in air-packed Caspian Kutum fillets during the refrigerated storage at 4°C was investigated. Changes in some quality indexes of fish including chemical attributes including TVB-N, PV and TBA and microbial communities counts including mesophilic (TMC), psychrophill (TPC) and lactic acid bacteria (LAB) were determined during days of 0, 3, 6, 9 and 12. The results showed that TVB-N, PV and TBA indices in treatments were higher than control. Mesophilic and psychrophill bacteria in control sample (with 6.53 and 6.71 CFU/g, respectively) reached to acceptable amount, while treatments containing preservatives showed a better condition in both TPC (with 6.63 to 6.93 CFU/g) and TMC (with 6.67 to 6.90 CFU/g) (P<0.01). Also, growth of LAB has controlled at 9 days (with 6.88 CFU/g) but stopped in treatment samples at the same days (P<0.01). The results revealed that Nisin Z in combination with sodium citrate can therefore be used as the effective preservatives to shelf-life of Caspian Kutum fillets during refrigerated storage.