Enhancing microbial safety of fresh produce while maintaining product quality

Microbial safety of fresh fruits and vegetables has become a concern in recent years as a result of several well publicized outbreaks of foodborne illnesses associated with cantaloupe, lettuce, spinach, and pepper.  Fresh produce is grown in open fields that offer many opportunities for human pathogen contamination. Furthermore, fresh produce is likely to be consumed raw and there is no “kill” step such as cooking available to guarantee the safety of fresh produce.  This presentation first reviews recent outbreaks of diseases associated with fresh produce, and possible reasons for the increased occurrence of the outbreaks.  Some pre-harvest strategies such as Good Agricultural Practices will also be briefly discussed.  Much of the presentation addresses postharvest interventions- chemical, biological, and physical means to inactivate human pathogens either on or in fresh produce.  Although chemical sanitizers such as chlorine are often used by the industry, the effectiveness of the sanitizers is very limited. Possible internalization of human pathogen within produce precludes effective disinfection by washing and sanitizing treatments. Commercial application of biological interventions such as bacterial phages and beneficial bacteria on fresh produce has not been realized. Physical treatments such as hot water and cold plasma represent some of our current research efforts that may have a potential to be applicable to some fresh fruits and vegetables. Ionizing irradiation is probably the only non-thermal processing technology that is capable of inactivating pathogens that are located both on the surface of and inside fresh produce.  Irradiation of fresh produce will be discussed in terms of regulatory approval, labeling requirements, effectiveness in inactivation of pathogens, effect on produce quality, and consideration for commercial application.  Despite active research in the area of produce safety, ensuring the microbial safety while maintaining nutritional and sensory quality of the products remains a challenge.