Pre- and Postharvest Preventive Measures and Intervention Strategies to Control Microbial Food Safety Hazards of Fresh Leafy Vegetables

Abstract

This review includes an overview of the most important preventive measures along the farm to fork chain to prevent microbial contamination of leafy greens. It also includes the technological and managerial interventions related to primary production, postharvest handling, processing practices, distribution, and consumer handling to eliminate pathogens in leafy greens. When the microbiological risk is already present, preventive measures to limit actual contamination events or pathogen survival are considered intervention strategies. In codes of practice the focus is mainly put on explaining preventive measures. However, it is also important to establish more focused intervention strategies. This review is centered mainly on leafy vegetables as the commodity identified as the highest priority in terms of fresh produce microbial safety from a global perspective. There is no unique preventive measure or intervention strategy that could be applied at one point of the food chain. We should encourage growers of leafy greens to establish procedures based on the HACCP principles at the level of primary production. The traceability of leafy vegetables along the chain is an essential element in ensuring food safety. Thus, in dealing with the food safety issues associated with fresh produce it is clear that a multidisciplinary farm to fork strategy is required.

Scientific Opinion on the risk posed by pathogens in food of non‐animal origin. Part 2 (Salmonella and Norovirus in berries)

“…Preventive measures are not always easy to implement as farmers may not control adjacent land activities or the land history does not include knowledge of the extent or level of pathogens in the soil or the time necessary to reduce these to acceptable levels (Suslow et al, 2003;James, 2006;Gil et al, 2013).…”

Scientific Opinion on the risk posed by pathogens in food of non‐animal origin. Part 2 (Salmonella, Yersinia, Shigella and Norovirus in bulb and stem vegetables, and carrots)

“…If the evaluation concludes that contamination in a specific area is at levels that may compromise the safety of crops, in the event of heavy rainfall and flooding for example, intervention strategies should be applied to restrict growers from using this land for production of these vegetables until the hazards have been addressed. Preventive measures are not always easy to implement as farmers may not control adjacent land activities, or the land history does not include knowledge of the level of pathogens in the soil or the time taken to reduce these to acceptable levels James, 2006;Gil et al, 2015).…”

Risk Assessment or Assessment of Risk? Developing an Evidence-Based Approach for Primary Producers of Leafy Vegetables To Assess and Manage Microbial Risks

“…During a field growing season, any foodborne pathogens present will encounter variable environmental conditions such as UV radiation (18), humidity (8), and temperature (14,16) that affect their persistence, particularly on leaf and soil surfaces. Quantitative microbial RAs have been developed to study the prevalence of Escherichia coli O157:H7 (23), Salmonella (23,30), and Listeria monocytogenes (7) in leafy greens.…”

“…Consequently, production standards have been developed that follow the principles of hazard analysis and critical control point (HACCP) systems and apply a systems-based approach to managing food safety (14,19). Growers are required by many customers to adhere to a quality assurance scheme (QAS), either an industrywide QAS such as GlobalG.A.P.…”

“…An estimated 0.5-to 2-log reduction in naturally present microflora is the best that can be expected from most produce washing systems (2,29), and even in such systems planktonic contaminants in the wash water may crosscontaminate other clean produce entering the system. The best approach is to ensure that introduction of microbial contamination during primary production is minimized or eliminated; produce washing or disinfection should not be relied on as the main hazard control measure (14).…”