Impact of smoking techniques and storage conditions on microbial safety and stability of catfish (Clarias gariepinus)
Microbial spoilage is one of the causes of quality deterioration of smoked catfish during storage. The impact of smoking techniques and storage conditions on the quality of smoked catfish were determined. Smoked dried catfish were produced using traditional smoking kiln (44-gallon drum kiln) and an improved smoking kiln from Nigerian Institute for Oceanography and Marine Research (NIOMR). The smoked dried catfish were packed in polythene bags and stored at ambient (30 ±3°C), refrigerated (4 ±1°C) or frozen at (-18±2 °C) for 12 weeks. The moisture content and acidity (pH) of the smoked fish products fluctuated during the storage period. Smoking reduced the total viable count (TVC) of the microorganisms significantly (P<0.05) from 5.71 to between 3.18 and 3.93 log CFU/g for traditionally smoked and improved kiln smoked fish samples respectively. The microbial total viable count (TVC) of the stored smoked fish products increased as the storage period increased, the frozen stored smoked fish products had the highest TVC followed by the refrigerated stored smoked fish products and the ambient stored smoked fish products had the least TVC but there was no significant difference (P>0.05) among the storage conditions studied. The stored smoked fish products were acceptable up to 8th week storage period based on microbial load. Gram negative organisms, Pseudomonas sp. and Aeromonas sp. were the bacteria identified while Penicillium sp. and Aspergillus niger were the fungi identified in the smoked fish products during the storage period. Microbial safety and shelf life of stored smoked catfish depends on the smoking technique adopted, storage condition and duration of storage.
Keywords: Catfish, Smoked fish, Ambient temperature, Refrigerated, Microbial loads