Effect of different storage temperatures on bacterial spoilage of Oreochromis niloticus

Abstract

This study determined the bacterial organisms associated with Oreochromis niloticus spoilage at two storage temperatures (6 and 20°C) and also assessed the ability of the individual bacterial isolates to cause spoilage at the two storage temperatures. Bacteriological analysis revealed the association of five bacteria genera: Pseudomonas, Serratia, Streptococcus, Bacillus and Escherichia with Oreochromis spoilage at low temperatures. The shelf life of O. niloticus was about 9 days at 6°C with a bacterial load of 6.8x10⁵ cfu/ml. Although a total bacterial count of 2.3x10³ cfu/ml was obtained on fish samples at storage temperatures of 20°C on the 9^th day of storage, there was no spoilage of fish samples at that temperature. Experiments on the spoilage of fresh sterile fish flesh indicated that Pseudomonas, Serratia and Bacillus were the agents of spoilage at 6°C and that temperatures as low as 20°C are needed to hinders bacterial proliferation and hence prevent bacterial spoilage of the fish.

Keywords: fish, bacterial spoilage, Oreochromis niloticus, storage temperature

Animal Production Research Advances Vol. 1(1) 2005: 20-23