Assessment of the Efficacy of Various Sanitizing Agents in Reducing Microbial Load in Leafy Vegetables
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Date
2018
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Abstract
Foodborne illnesses have been associated with the consumption of fresh produce, specifically leafy vegetables due to their soft texture and method of cultivation. As a safety precaution, these vegetables are usually cleaned with chemical sanitizers before consumption, hence the efficacy of various chemical sanitizers was tested on leafy vegetables to ascertain their potency. Lettuce, cabbage and spinach were collected aseptically in plastic bags from Kumasi central market to the laboratory. Samples were taken through pretreatment by washing with distilled water, sanitizing with 70% alcohol under Ultra Violet light to ensure complete sterility. Test organisms E. coli, Salmonella and L. monocytogenes inoculum were obtained from the microbiology laboratory of the Centre for Scientific Research into Plant Medicine (CSRPM), Akuapem Mampong and inoculated on samples using the dip method. Samples dried for an hour at 37oC and were sanitized with varying concentrations of peracetic acid, acetic acid, hydrogen peroxide, sodium hypochlorite and sodium chloride within varying exposure times. Microbial analysis were carried out at a temperature of 37oC for 48 hours on all samples using spread plate technique on plate count agar (PCA) for enumerating colonies that will grow on plates. Results showed that there was a significant difference (P˂0.05) between the loads on various test organisms. However, E. coli was chosen as a model organism. After inoculating cabbage, lettuce and Spinach, the results showed no significant difference (P>0.05) in the loads, thus cabbage leaves were selected for the assay. Inoculum sample of pretreated leaves showed 0 CFU/g and served as a control. Plate count before and after sanitizer treatment were also obtained and used to determine the potency of chemicals on microorganisms through the reduction in microbial population. All the sanitizers were found to have an efficacy of 99.99% except for sodium chloride which was 99.90%.
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A thesis submitted to the Department of Food Science and Technology, College of Science, in partial fulfilment of the requirements for the degree of Master of Science in Food Quality Management.