Determination of Microbial Growth and Survival in Salad Vegetables through in Vitro Challenge Test

Abstract

Current study attempted to examine the growth and subsequent survival of the common spoilage bacteria in vegetable samples collected from Dhaka, Bangladesh. Carrot, cucumber, tomato and lettuce samples were obtained from local markets and rendered free of contaminants. Each sample was then inoculated separately with an array of 9 test bacteria, resulting in the initial load of 105 cfu/g. The results revealed more than 6-log reduction of Salmonella spp. in carrot and tomato samples, Shigella spp. in carrot, lettuce and cucumber samples, Aeromonas spp. in tomato samples, Pseudomonas spp. in lettuce samples, and Listeria spp. in cucumber samples. No significant reduction in E. coli was observed in the cucumber samples, while in carrots and tomato samples, approximately 2- log reductions was found. Demonstration of the capacity of vegetables to influence microbial growth would further aid in the maintenance of the food quality and stability as well as their shelf life. Conducting such experiments after the quantification of spoiling microorganisms thus imparts a complete bacteriological profile, which is of public health significance.