Pre-harvest sanitisation of leafy green vegetables (VG22008)

What was it all about?

The first critical food safety risk reduction step in prevention of pathogen contamination on leafy vegetable crops is by removing sources of contamination in the field. 

In 2023, this project reviewed the published literature and industry practices on emerging and current pre-harvest risk management strategies of leafy vegetables that are, or can be eaten raw. In particular, the project assessed the feasibility of sanitising the crop and/or irrigation water in the field to prevent human pathogen transfer from the field to the packhouse and to reduce the food safety risk to the consumer. The feasibility of using pre-harvest sanitisers was examined in a ‘desktop’ literature review by scrutinising published (including grey literature) reports and through consultation with key industry stakeholders. 

The extensive literature review revealed that very few studies had specifically studied the key issue of whether an optimised pre-harvest sanitisation of crop via irrigation water or sprayer can reduce microbial load. The review identified major scientific knowledge gaps, as well as both regulatory and logistical barriers, which would hinder the uptake of this novel approach. It is clear that there are practical limitations of this strategy such as efficacy in sanitisation of the lower surface of leaves, and the potential risk of re-contamination after pre-harvest sanitisation of the crop, unless applied very close to harvest. 

Overall, it was concluded there are limited opportunities for using pre-harvest sanitisation of the crop under normal conditions, but it could be recommended under high-risk scenarios e.g. extreme weather events. Further, if irrigation water is not of sufficient hygienic quality, disinfection (e.g. filtration, UV, chemical) of irrigation water may offer an alternative to manage pre-harvest microbial load.