Assessment of microbial contamination in street-vended ready-to-eat food products

Abstract:

Street-vended Ready-to-Eat (RTE) foods supply affordable meals for millions of Thai consumers, yet their microbial safety receives limited systematic monitoring. This research assessed contamination levels across five RTE food categories som tam, sandwiches, rice dishes, fresh juices, and fried snacks sold in Bangkok and Chiang Mai. A total of 300 samples (60 per category) collected over October 2022 to March 2023 were analysed for total plate count, coliform count, Staphylococcus aureus, Salmonella spp., and Escherichia coli using ISO protocols. Som tam samples showed the highest mean TPC (5.8 log₁₀ CFU/g), exceeding the Thai FDA limit of 5.0 log₁₀ CFU/g. S. aureus was isolated from 43.7% of samples, and Salmonella from 8.3%. Only 38.7% of samples met Thai FDA limits. Vendor hygiene scores were the strongest predictor of microbial load (r = −0.74, p<0.001). Seasonal surveillance and vendor training are recommended to reduce public health risk.