Effects of spring onion (Allium fistulosum) and turmeric (Curcuma longa) marinade on the shelf life of smoke-dried Clarias gariepinus

Abstract

This study was conducted to determine the effect of spring onion marinade and turmeric marinade on the microbial load of smoked-dried Clarias gariepinus stored at ambient temperature (37⁰C) for six weeks. Forty (40) fishes with an average weight of 500g were gutted, washed and randomly assigned to the treatments. The experimental treatments were the control, turmeric, spring onion and turmeric. The fishes were soaked in the treatments for 20 minutes. After smoke-drying, the fishes were stored and comparative analysis of the microbial load of each treated fish samples were done biweekly for six (6) weeks. The fish samples were analysed using Potato Dextrose Agar and Nutrient Agar for fungi and bacteria respectively. There was a general increase in microbial load as the storage period progressed. After 6 weeks of storage at ambient temperature, the study showed sample B (Spring Onion) had the highest (1.3´10⁶ cfu/g) mean bacterial load and the least (8.8x10⁵ cfu/g) was in sample C. Samples A (control) and C (turmeric marinade) had the highest (1.4´10⁵ cfu/g) mean fungal load while the least was seen in Sample B (9.3´10 cfu/g). Seven bacterial species namely, Bacillus subtilis, Enterobactera erogenes, Pseudomononas sp., Streptococcus pyogenes, Micrococcus sp., Proteus sp., and Klebsiella sp and six fungal species namely, Mucor piriformis, Candida sp., Aspergillus sp, Rhizopus sp., Penicillium sp, and Fusarium sp were observed in the study. It is recommended that turmeric marinade should be employed in smoke-drying fish as it had the least microbial load and as such it would have the longest shelf life.