Efficacy of vinegar, salt solution and lemon juice as antimicrobial agents in reducing the microbial load of lettuce sold at ayeduase, a suburb of kumasi, ghana

Background: Vegetables are known to provide enormous health benefits to man. Despite these, there is a great potential of microbial contamination. Objective: This study assessed the effect of increasing concentration of antimicrobial agents; vinegar, lemon juice and salt solution on the microbial load as well as their efficacy on the microbial isolates found on the lettuce sold in Ayeduase, a suburb of the Kumasi Metropolis, Ghana. Method: 10g of lettuce was pulsified with 90mls each of 0.3M, 0.5M, 0.7M, and 0.9M concentration of vinegar, lemon juice and salt solution. Serial dilution and colony counting were performed by pour plating on PCA (Plate Count Agar) and Coliform counts for each sample and concentration. Isolates were identified using standard biochemical methods. Results: The mean microbial load ranged from highest of 3.94×107CFU/100ml using 0.3M salt solution to the least 2.83×102CFU/100ml washing with 0.9M Apple Cedar vinegar. The total microbial counts significantly decreased (P<0.05) with increasing antimicrobial concentration and in comparison, with control (distilled water washing 1.57×108 CFU/100ml). Six different bacteria species and fungi species were isolated of which Escherichia coli and Salmonella were the most resistive towards the action of the antimicrobials with Enterococcus, Streptococcus and Staphylococcus being the most susceptible species. Fungi species proved fairly resistant to the activity of the antimicrobials. Conclusion: Increasing vinegar concentration has the tendency to reduce microbial loads on vegetables and hence its application is recommended.