Sensory and chemical changes associated with microbial flora of Oreochromis niloticus stored in ice

One batch of Oreochromis niloticus samples attained to 25 kg was examined periodically each two days intervals to asses the sensory, physical, chemical and microbiological parameters during ice storage along of it’s validity. Samples under study kept their normal organoleptic characteristics under ice storage (at 0°C) for 10 days. The mean values for each of pH, TVB-N and TMA-N ranged from (5.82 ± 0.01 to 6.50 ± 0.01), (9.38 ± 0.11 to 30.03 ± 0.14) and from (2.78 ± 0.01 to 10.02 ± 0.03) respectively. The mean total aerobic, psychrophilic bacteria, hydrogen sulfide producing bacteria, Pseudomonas, proteolytic, and lipolytic bacterial counts were ranged from (3.5 x 10³ to 2.2 x 10^6), (1.1 x 10³ to 1.2 x 10^6), (7.8 x 10² to 1.6 x 10^4), (9.2 x 10², to 5.5 x 10^4), (8.8 x 10² to 3.1 x 10^4) and from (1.5 x 10² to 3.3 x 10³) CFU/g respectively. The bacterial isolates in the examined fish samples were Pseudomonas putida biovar B, Pseudomonas fluorescence, Shewanella putrefaciens, Aeromonas sobria, Aeromonas caviae and Aeromonas allscharophilia with a different incidence. In conclusion, fish chilled to the temperature of melting ice (0°C) as soon as possible after capture and maintained at this temperature until it reaches the consumers.