Food Safety Magazine

News | March 6, 2014

Study Links Temperature Abuse to Pathogen Growth in Bagged Salad

Study Links Temperature Abuse to Pathogen Growth in Bagged Salad

Source: California Leafy Greens Marketing Agreement

Health experts emphasize that food safety is a shared responsibility that starts on the farm, but is important all along the supply chain. For fresh produce, particularly leafy greens which are often eaten in an uncooked state, proper food safety practices are critical to reducing foodborne illness. The California Leafy Greens Marketing Agreement (LGMA) is devoted to ensuring a set of science-based food safety practices are being following on leafy greens farms. But LGMA members lose the ability to protect consumers when the leafy greens they carefully produce leave their coolers in California and head to dinner tables around the world.

A new study published In the February 2014 issue of the Journal of Food Production takes a look at the effects of temperature fluctuations during transit and in retail storage and display with respect to the growth of pathogens in bagged salads. In this case, the pathogens examined were E. coli 0157:H7 and Listeria monocytogenes. The project, conducted by researchers at Michigan State University and California Polytechnic State University, San Luis Obispo, claims the to the first large-scale commercial study to report the impact of fluctuating temperatures on microbial growth for fresh-cut leafy greens distributed in the United States.

The study was done over a 16-month period. A series of time and temperature profiles were obtained for bagged salad greens from 16 transport routes covering four geographic regions, as well as during retail storage and display at nine supermarkets. Not surprisingly, the study found that temperature abuse has the potential to increase the chance for pathogen growth. The authors note that their findings, and those of others, “demonstrate that temperature abuse of commercially produced, fresh-cut salad greens is most likely to occur during retail storage.” However, they note that abuse can occur during transportation, particularly during warm weather periods.

An abstract of the study is available here