Microbiological quality of traditional and improved kiln smoked catfish (Clarias gariepinus; Pisces; Clariidae) in Lake Chilwa Basin

Microbiological quality of smoked catfish (Clarias gariepinus) locally known as Mlamba was assessed in this study where traditional and improved smoking kilns were used to smoke fish. There were significant differences (p = 0.05), with respect to total viable bacterial counts between traditional kiln smoked and improved kiln smoked catfish. Traditional kiln smoked catfish harbored significantly higher total viable counts as well as a higher population of Escherichia coli compared to improved kiln smoked catfish.

Abstract

Microbiological quality of smoked catfish (Clarias gariepinus) locally known as Mlamba was assessed in this study where traditional and improved smoking kilns were used to smoke fish. Catfish is common fish caught in abundance in the Lake Chilwa basin, and the fish is usually smoked to reduce postharvest losses and increase shelf life. Samples were collected in sterile polythene bags, well labeled, and collected in cooler boxes transported ready for laboratory analysis. One gram representative sample was obtained aseptically from the muscle of the fresh and smoked catfish (Mlamba) samples. The samples were grounded, and fourfold serial dilutions (10⁻¹–10⁻⁴) of the homogenized samples were made using sterile distilled water. Fish samples were analyzed for total plate count (TPC), Escherichia coli counts, and pathogenic organisms (Salmonella) following the methods prescribed by AOAC (Official methods of analysis, Association of Official Analytical Chemistry, Arlington, VA, 2000). Each analysis was carried out in triplicates. There were significant differences (p = 0.05), with respect to total viable bacterial counts between traditional kiln smoked and improved kiln smoked catfish (5.6 × 10⁶ cfu/g, 1.9 × 10⁶ cfu/g, respectively). Traditional kiln smoked catfish harbored significantly higher total viable counts as well as a higher population of E. coli compared to improved kiln smoked catfish. However, for both types of smoking kilns there were detected levels of pathogenic bacteria Salmonella with traditional kiln smoked catfish containing 2.1 × 10⁴ cfu/g which were significantly higher than amount found in improved kiln smoked catfish (1.5 × 10⁴ cfu/g; p = 0.05). Salmonella is a microbe of public health importance and has implications on the handling and source of the fish.

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