Microbial Diversity and Quality of Ready-to-Eat Salad: An Underexplored Area of Local Hotels

Abstract

Ready-to-eat salads, celebrated for their myriad health benefits, have become a ubiquitous dietary choice. However, concerns have surged in light of recent illness outbreaks linked to consumption of raw salads. In response, this study aimed to assess the microbiological quality of ready-to-eat salad, focusing on shelf-life estimation and microbiome characterization. A random sample of twelve salads went through comprehensive microbiological analysis and 16S rRNA metagenomic profiling. The salads appear to be potentially hazardous for ingestion based on the mean values of 7.66 log cfu/gm for aerobic mesophilic count and 7.33 log cfu/gm for psychrotrophic count. In addition, total coliform and Enterobacteriaceae were found (mean 3.66 log cfu/gm for both), but fecal coliform was completely absent. Firmicutes (47.18%), Cyanobacteria (28.19%), Proteobacteria (23.24%), Bacteriodetes (0.88%), and Actinobacteria (0.41%) were the top five phyla discovered. Of the salad samples, Weissella (54.86%) seems to be the most prevalent genus. Notably, genera such as Pseudomonas, Acinetobacter, and Enterobacter, potential human pathogens, exhibited more than 1% abundance. Additionally, spoilage-associated LAB organisms, including Leuconostoc and Lactobacillus, and Lactococcus were detected. Furthermore, with the exception of Weissella, the majority of the species showed a positive correlation between protein concentration and spoilage. Increased pH levels and elevated moisture content create favorable conditions for the proliferation of specific pathogens, consequently diminishing the shelf life of the salad. Additional research is necessary to fully grasp the intricacies of the microbiome in salads and to establish protocols that uphold quality standards and ensure the protection of public health.