Microbiological assessment of traditional smoked silver catfish (Chrysichthys nigrodigitatus)

Smoked fish is relished food item in many dishes in Nigeria. Traditional smoked silver catfish (Chrysichthys nigrodigitatus) that floods the smoked fish market of the Lagos State of Nigeria are not microbiologically shelf-stable; hence, the need for a study on their microbiological quality and safety. ‘Fresh silver catfish’ (100 samples) and smoked silver catfish (100 samples) were collected from 20 different processing centres and the fresh samples were smoked with convectional smoke kiln as control and microbiological analyses were conducted. Each batch was assessed for: total viable count (TVC), fungal count (FC), Listeria monocytogenes (LM) count, Staphylococcus aureus (SA) count, Salmonella Paratyphi (SP) count and presence or absence of Escherichia coli (EC). The results obtained showed significant variations (p<0.05) for all the microbial counts of the smoked fish samples. The mean TVC range of 6.6 x 106 - 8.8 x 108 cfu/g was recorded for fresh silver catfish samples and 2.0 x 104 - 8.6 x 104 and 1.0 x 103 - 5.4 x 103 cfu/g for samples of smoked silver catfish. 5.0 x 103 - 6.4 x 103 cfu/g was recorded for fresh silver catfish samples and from 5.6 x 102 - 60.4 x 102 cfu/g and 1.0 x 102 - 3.5 x 102 cfu/g for samples of smoked silver catfish (SA). Mean (LM) of fresh silver catfish samples was 1.8 x 102 - 2.5 x 102 cfu/g and 1.3 x 101 - 13.2 x 101 cfu/g for samples of smoked silver catfish. Mean (FC) of smoked silver catfish from local drum kiln was 4.1 x 101 - 8.2 x 101 cfu/g. The samples of smoked silver catfish using conventional smoke kiln showed no count for L. monocytogenes, S. Paratyphi and E. coli.