Effect of modified atmosphere packaging and multi-layer flexible films on pH of smoked Kutum Fish (Rutilus frisii kutum)

Document Type : Primary Research paper



In this study the effect of different concentrations of three gas mixture (carbon dioxide, nitrogen, oxygen), and also vacuum conditions and flexible multi-layer films on pH of smoked kutum fish (Rutilus frisii kutum) at ambient condition (T = 25 °C) were evaluated. Ordinary conditions as control packagingwere compared with four types of modified atmosphere packaging: (70% N2 + 30% CO2), (30% N2 + 70% CO2), (45% CO2 + 45% N2 + 10% O2), and vacuum conditions. Smoked Kutum fishes were packaged  in flexible multi-layer films under  modified atmosphere packaging, 3-layer {(PET(12)/AL(12)/LLD(100)), 4-layer (PET(12)/AL(7)/PET(12)/LLD(100)) and 3-layer (PET(12)/AL(7)/LLD (100))}. Samples were performed chemical test (pH) at different times during 60 days ,with 15 treatment ,3 run, statistical analysis  and comparison of data, were done by software SAS (Ver:9/1) and also Duncan’s new multiple range test, with confidence level of 95% (P<0.05). The shelf  life of smoked kutum fishes (according to pH changes) were reported under conditions 1, 2 and 3  in 4-layer, 60, 58 and 45 days and in  vacuum conditions were about 40 days, in 3-layer (AL:12), under conditions 1, 2 and 3 and vacuum conditions were 55, 50, 40 and 35 days, with 3 layers (AL:7), under  conditions 1, 2 and 3 were45, 40 and 35 days and in  vacuum conditions were 30 days. Maximum change of pH was related to 3-layer (AL:7) under 30% CO2 + 70% N2 and ordinary condition, the lowest changes belonged to 4-layer under 70% CO2 + 30% N2. The pH variable has not decreased rapidly, in each treatments during storage times (60 days), while can be explained by characteristic of this multi-layer flexible pouch with less water vapor and oxygen permeability, and increasing CO2 caused to control some chemical reactions such as pH changes in samples.