Effect of Ginger and Garlic Marinates on Growth of Microbial Contaminants in Cold-Smoked Catfish (Clarius gariepinus) Stored at Room Condition

Abstract

Aim: In this study, the preservative effect of potassium sorbate, ginger, garlic and a combination of ginger – garlic on the microbiological quality and shelf stability of cold-smoked Catfish (Clarius gariepinus) were investigated. Methodology: A total of 100 fresh catfish from Michael Okpara University of Agriculture, Umudike (MOUAU)  Nigeria Fish Farm was used for the analysis. The fish were processed and divided into five lots of twenty each. This was followed by marinating in baths containing 0.5% potassium sorbate, 3% ginger, 3% garlic, and a mix of 1.5% ginger and 1.5% garlic each and a control for 2h. Afterwards, the treated fish was cold-smoked for 8 h and then stored at room temperature (28 ± 2°C). Fish samples were collected at 2-day intervals to determine total viable count, total fungal count, and bacterial counts (Escherichia coli, Salmonella, Staphylococcus sp, and Listeria sp.). Results: Findings of this study revealed that potassium sorbate, ginger, garlic, and ginger-garlic blends enhanced the microbiological safety of cold–smoked Catfish (Clarius gariepius). The result showed that although counts of some microbial contaminants increased in the cold-smoked fish, however, it varied (p˂0.05) with the treatment during storage. Comparatively, 1.5% ginger - 1.5% garlic marinate was the most effective and performed considerably higher (p˂0.05) than 0.5% potassium sorbate in the reduction of the microbial contaminants. In this study, the lowest total viable counts were observed in the 3% ginger–treated cold smoked fish (8.7x105 cfu/g) while the untreated sample was the most contaminated (1.19 x 106 cfu/g) at pre-storage. A significant increase in the total viable count was observed in all the samples during storage however, 3% garlic recorded the least (1.13 x 106 to 2.84 x106 to 3.48x106 cfu/g) and the highest in the untreated sample (1.19 x 106 to 3.38 x 106 to 3.66x 106 cfu/g). Overall, 1.5%ginger+1.5%garlic blend was most effective on E. coli while 0.5% potassium sorbate was on Salmonella at ambient storage. Listeria monocytogenes was most susceptible to all the treatment, the growth of fungi steadily increased in the treated cold smoked fish during ambient storage. Conclusion: The study found that 3% ginger, 3% garlic, 1.5% ginger - 1.5% garlic mixture inhibits significantly the growth of microbial contaminants relatively with 0.5% potassium sorbate in cold-smoked fish during ambient storage.