Preservative Effect of Vernonia amygdalina Extract on Microbial Activity, Proximate Composition and Sensory Evaluation of Smoked-dried African Catfish Clarias gariepinus (Burchell, 1822)

Abstract

The effect of Vernonia amygdalina extract on microbial activity, proximate composition and sensory evaluation of smoked-dried Clarias gariepinus stored at 32.0±2°C was determined over the period of 21 days. The experimental treatments were the control, 0.5%, 1%, 1.5% (w/v) Vernonia amygdalina extract solutions. 52 fish of average mean weight of 30.98±1.32g were degutted, washed and randomly assigned to the treatments and soaked in the extract solutions for 30 minutes and later smoked-dried for 12 hours. Six bacterial species namely, Bacillus subtilis, Corynebacteria sp, Proteus mirabilis, Streptococcus faecalis, Staphylococcus albus and Staphylococcus aureus were observed in the study. There was no increase in the microbial loads in all the treatments except in the control which increased from 27×103 to 40×103 cfu. Highest crude protein content (48.08±0.82%) was recorded in the control while the least value (39.67±0.04%) was obtained in the fish treated with 0.5% concentration of the extract. There was no significant difference (P>0.05) in the sensory evaluation among all the treatments and the control. This study reveals that V. amygdalina extract can be used as preservative in protecting smoked-dried C. gariepinus from bacterial spoilage, thus limiting economic loss and possible health risk to consumers.