Chapter 5 - Leafy vegetables

Abstract

Foodborne illness outbreaks linked to the consumption of contaminated leafy greens continue to occur globally. Regulatory agencies have developed and implemented guidance and regulations as efforts to mitigate crop contamination and human illness. A holistic approach to control must be realized since no single factor; contaminated agricultural water, soil amendments, flooding of fields, and wildlife contribute to the contamination of leafy greens. Enteric microorganisms, particularly bacteria and viruses, can contaminate the surface and internal structures of edible leafy tissue both pre- and postharvest. This chapter describes outbreaks associated with leafy vegetables and the potential sources of contamination associated with those outbreaks. Consideration is given to geographical regions and agricultural practices of those regions that may influence preharvest contamination. Harvesting and processing practices can significantly influence the microbial load of a product. Decontamination technologies for leafy greens are evaluated with respect to efficacy, consumer acceptance, and sustainability. Information regarding the interaction of enteric microbes with plant tissues, how that affects survival, and the molecular events underlying that interaction are highlighted. Understanding the complexity of the enteric pathogen-plant tissue interaction provides a solid foundation for the development of strategies to control contamination pre- and postharvest. Increased export and import of fresh leafy vegetables dictates understanding global production and processing strategies and government regulations. Seeking new technologies and implementing those technologies will markedly improve the microbiological safety of leafy vegetables.