Changes in Sensory and Microbiological Quality Indices of Nile Tilapia (Oreochromis niloticus) and Grey Mullet (Mugil cephalus) During Ice Storage

This study was carried out to determine quality changes of Nile tilapia (Oreochromis niloticus) and grey mullet (Mugil cephalus) stored in ice. Changes in sensory and microbiological attributes were evaluated during 16 and 14 day of storage for Nile tilapia and grey mullet, respectively. The overall sensory scores of both raw and steamed Nile tilapia and grey mullet gradually decreased with the ice storage. Highly significant correlation was found between the overall sensory scores of both raw and steam cooked Nile tilapia and grey mullet and storage time. The shelf life of Nile tilapia and grey mullet were 8 days in ice. The mesophilic aerobic bacterial count of Nile tilapia and flathead grey mullet flesh increased gradually during storage in ice from 2.38x10^3and 7.67 x10^2 CFU/g flesh to 4.10x10^4 and 2.13 x10^4 CFU/g flesh after eight day of ice storage. The psychrophilic aerobic bacterial count increased gradually during storage in ice from 5.97x10^2 and 4.76 x10^3CFU/g flesh to 6.30x10^4 and 1.66 x10^5 CFU/g flesh after eight day of ice storage. Psychrophiles had faster rate of increment during storage in ice, compared to mesophiles. Based on results of sensory evaluation the iced raw and steamed Nile tilapia and grey mullet samples could be classified into three categories of quality grade as follows :(1) high quality grade (stored in ice for not more than 4 days) (2) acceptable grade (stored in ice for more than 4 days, but less than 8 days), (3) unacceptable grade (stored in ice for more than 8 days).