New Study Shows Bagged Cut Lettuce at Higher Risk of Salmonella

A new report published in the American Society for Microbiology's December issue of Applied and Environmental Biology shows that traces of juices released from salad leaves as they became damaged can significantly enhance Salmonella enterica salad leaf colonization.

While salad leaves are an important part of a healthy diet, in recent years, they have been associated with a growing risk of food poisoning from bacterial pathogens such as Salmonella enterica. The study shows that juices released from the cut-ends of the salad leaves enabled the Salmonella to grow in water, even when it was refrigerated. Additionally, exposure to the the salad juice helped the Salmonella cells attach to the salad leaves so strongly that washing could not remove them.

Over five days of refrigeration, even traces of juice within the salad bag fluids were shown to increase Salmonella growth in water by up to 280-fold over control cultures, and enhancing salad bag colonization

The study showed that exposure to salad leaf juice may contribute to the persistence of Salmonella on salad leaves, and strongly emphasizes the importance of ensuring the microbiological safety of fresh produce.