Effect of Some Preservatives on the Microbial Quality of Cold-smoked Catfish at Refrigerated Temperature

Aim: This study investigated the preservative effect of potassium sorbate, ginger, garlic, and a blend of, ginger and garlic on the microbiological quality and shelf stability of cold smoked Catfish (Clarius gariepinus) at refrigerated storage.

Methodology: One hundred (100) of the freshly harvested catfish obtained from the MOUAU Fish Farm were processed and divided into five lots of 20 each. Four marinating baths containing 0.5% potassium sorbate, 3% ginger, 3% garlic, and a blend of 1.5% ginger and 1.5% garlic respectively were prepared. Each catfish lot except the fifth lot (which served as a control) was marinated for 2 h and cold smoked for 8 h. The samples were then stored for fourteen days at refrigeration temperature (4 ± 2 °C during which analyses were carried out. The Total viable count, Total fungal count, and bacterial counts (Escherichia coli, Salmonella, Staphylococcus sp, and Listeria sp) of the catfish samples before, during, and after storage were analyzed.

Results: The total viable count (TVC) was reduced from 8.7x105 to 1.2x105 CFU/g, 1.13 x106 to 2.4x105 CFU/g, 1.09 x 106 to 2.00 x105 CFU/g, 9.60 x105 to 1.50 x105 CFU/g, and 1.19x106 to 3.00x105 CFU/g for 3% ginger, 3% garlic, 1.5% ginger +1.5% garlic, 0.5% potassium sorbate, and the control at refrigeration storage respectively. All the treatments were effective against E. coli, Listeria monocytogen, and Salmonella count. Similarly, the 3% of ginger treatment recorded counts of 1x105 CFU/g for Staphylococcus counts, during refrigeration storage. Furthermore, the total fungal count decreased for all the treatments.

Conclusion: The study found that cold smoked catfish treated with 0.5% potassium sorbate, 3% ginger, 3% garlic and a blend of 1.5% ginger and 1.5% garlic can be stored for 14 days at refrigeration storage provided the storage condition is maintained.