Microbial Risks Associated with Cabbage, Carrots, Celery, Onions, and Deli Salads Made with These Produce Items

The microbiological safety of cabbage, carrots, celery, and onions/scallions as well as deli (mayonnaise-based) salads that contain these items is the subject of this review. Between 2000 and 2007, the number of outbreaks in the United States associated with these raw produce items ranged from 6 (celery) to 18 (carrots). For cases with confirmed etiologies involving these 4 types of produce as well as coleslaw, chicken, seafood, and other vegetable-based salads, more than 50% of the outbreaks were attributed to viral agents. In contrast, Salmonella spp. served as the major etiological agent in outbreaks associated with potato salad. Surveys conducted on these produce items within the United States and other developed countries found either an absence or infrequent contamination with foodborne pathogens. Despite this low prevalence, experimental studies have demonstrated the potential for preharvest contamination, and this event is more likely to occur when exposure is close to harvest. Postharvest contamination of these produce items has been documented in several cases with water, equipment, and incoming product serving as the principal cross-contamination agent. Survival of contaminated product during subsequent storage is dependent on the storage temperature, produce type, and presence of mayonnaise. Chemical interventions may be relied on to reduce cross-contamination during produce washing operations but are limited in their ability to inactivate pathogens on the produce surface. In contrast, irradiation at dosages (1.0 kGy) approved for use in the United States is an effective treatment for killing pathogenic bacteria in fresh-cut cabbage, carrots, and celery.