Food safety assessment of last mile delivery as an alternative food distribution system for ready-to-eat multi-ingredient salad bowls.

A survey of ready-to-eat (RTE) multi-ingredient salad bowls, ordered online and delivered to customers via last mile delivery, was conducted in three European cities (Ghent, Belgium; Tulln, Austria; Burgos, Spain) to assess their microbiological quality, hygiene, and safety. Samples were analysed for foodborne pathogens (enumeration of presumptive Bacillus cereus, and detection of Listeria monocytogenes and Salmonella spp. per 25 g), a hygiene indicator (enumeration of generic E. coli), and general parameters (mesophilic aerobic plate count and enumeration of Enterobacteriaceae). Overall, the prevalence of generic E. coli, Salmonella spp. and B. cereus was similar in last mile delivered salad bowls intended for direct consumption and those present at retail (data extracted from scientific literature), although L. monocytogenes occasionally showed higher prevalence in retail products. Challenge tests examined the growth potential of L. monocytogenes and B. cereus during simulated delivery and prolonged storage (up to 24 h) after delivery, including scenarios of temperature abuse (9 °C or 22 °C) at the consumer level. Maintaining the cold chain is essential to prevent microbiological proliferation, although short urban delivery times (avg. 35 min) limit microbiological growth. The growth potential of L. monocytogenes and B. cereus remained low (<0.5 log CFU/g) when salads were stored at room temperature for up to 3 h. This aligns with the two-hour/four-hour rule, which states that food kept between 5 °C and 60 °C for less than 2 h can be consumed or refrigerated, can still be consumed but not refrigerated if held for up to 4 h, and must be discarded after 4 h, to prevent foodborne illness. During delivery, adherence to good practices, including hygiene of delivery personnel, preservation of packaging integrity, and prevention of cross-contamination, remains critical. The development of tailored prerequisite programs (PRPs) and clear guidance documents for delivery personnel in the last mile distribution sector is recommended, alongside efforts to raise consumer awareness of safe food handling practices at home.