Effect of Chilling on Microbial Load and Chemical Composition of Two Fish Species: Nile tilapia (Oreochromisnilotius) and Nile perch (Latesniloticus)

Abstract

This study aimed to identify the bacterial load and chemical composition of fresh and chilled Nile tilapia (Oreochromis nilotius) and Nile perch (Lates niloticus). This study was carried out on 18 fish: 9 Tilapia (Oreochromis nilotius) and 9 Nile perch (Lates niloticus) collected from El-morada fish market, tested fresh, and after chilled for 7 days for bacterial count and chemical composition. The bacterial loads of fresh Nile tilapia (Oreochromis nilotius) and Nile perch (Lates niloticus) were 6.4 ×102 and 7.5×102 CFU/gm respectively and for 7 days chilling the result were 1.17× 103 and 2.23×104 CFU/g respectively. The study showed that there was a significant increase (p< 0.05) of the number of total bacterial counts of frozen fish for 7 days, while there was no significant difference (p>0.05) in the number of bacterial counts between Nile tilapia (Oreochromis nilotius) and Nile perch (Lates niloticus). The chemical composition of fresh tilapia was 76% moisture, 24% dry matter, 5.1% ash, 33.1% protein, 7.4% fat. While the chemical composition of fresh Nile perch was 76.72% moisture, 23.28% dry matter, 6.01% ash, 31.1% protein, 7.21% fat. For 7 days chilled the result was 76% moisture, 24% dry matter, 5.1% ash, 33.1% protein, 7.4% fat for fresh tilapia and 76.70% moisture, 23.30% dry matter, 6% ash, 31.1% protein, 7.2% fat for fresh Nile perch. There is no significant difference (p >0.05) in the chemical composition of fresh fish and fish chilled for 7 days while there was significant difference (p< 0.05) between Tilapia (Oreochromis nilotius) and Nile perch (Lates niloticus).