EFSA assesses hazards for water use in the produce sector

The European Food Safety Authority (EFSA) has conducted a comprehensive evaluation of water quality in fresh and frozen produce operations. The EFSA sought input from the Panel on Biological Hazards (BIOHAZ) to provide a scientific assessment of microbiological risks linked to water use in the post-harvest treatment and processing of fresh and frozen fruits, vegetables, and herbs.

Water use in these agricultural activities presents a substantial risk of product contamination, with notable microbial hazards such as Listeria monocytogenes, Salmonella, E. coli, and viruses like norovirus.

The production of bagged salads, for instance, demands substantial water usage, covering various functions like washing, rinsing, fluming, chilling, cooling, general cleaning, sanitation, and disinfection. This reliance on water stems from the aim to conserve water and energy, particularly in cases where access to potable water is limited or costly.

Current practices typically involve the use of potable water for initial equipment and tank filling in the morning, with no replacement for several hours or even days. During this time, substantial volumes of fruits, vegetables, and herbs may undergo processing, as outlined in the report.

In addressing process water contamination, several factors come into play, including the type of produce being processed, the duration of operations, and the potential transfer of microorganisms between the product and the water.

To prevent cross-contamination resulting from the use of contaminated water, water disinfection measures are essential, aimed at eliminating or reducing microorganisms to an acceptable level without compromising product quality and safety.

The effectiveness of these disinfection measures depends on specific processing conditions, including the initial water quality and the chosen treatment method.

Common water disinfection treatments encompass chlorine-based disinfectants and peroxyacetic acid, and they require validation, operational monitoring, and verification to demonstrate their performance. Additionally, maintaining infrastructure, staff training, and cooling of post-harvest process water are important hygienic practices.

The experts' work included a literature review, analysis of outbreak monitoring data, and an industry survey. They concluded that relying solely on a basic prerequisite program (PRP) for water control is no longer feasible, and there's a need to adopt a Hazard Analysis and Critical Control Points (HACCP)-based approach for water management. This entails adhering to good manufacturing practices (GMP) and good hygienic practices (GHP) while implementing a water management plan and system.

The survey results revealed three under-implemented good practices in the industry: replacing infrastructure to prevent biofilm formation, monitoring and addressing biofilm formation in the water management system, and implementing water cooling. Additionally, it was noted that monitoring the quality of process water was often lacking or inadequate.

While some listeriosis outbreaks were traced back to processing plants, it's important to note that bacteria can also enter facilities through primary production. Despite investigations into such outbreaks, the exact route of contamination is rarely confirmed.

The report acknowledges that emerging agricultural practices like hydroponics, vertical farming, and urban agriculture may introduce pathogens into the food chain, although the scale of this risk is expected to be lower compared to conventional farming.

In light of their findings, the BIOHAZ Panel has recommended enhancing outbreak investigation reports with additional information and providing clear guidelines for companies on the use of water disinfection measures to maintain the microbiological quality of water used in post-harvest handling and processing of fruits, vegetables, and herbs.