Delphi expert elicitation to prioritize food safety management practices in greenhouse production of tomatoes in the United States

Abstract

Most of fresh tomatoes sold in the United States (US) are grown using protected agriculture. The risk of contamination and severe disease outbreaks in humans due to foodborne pathogens linked to fresh produce are a constant threat to the public and the industry. To date, there are limited tools to prioritize food safety management practices in commercial greenhouses to reinforce food safety in a timely manner. One rapid cost effective approach, originally applied in education and healthcare, is the Delphi method that uses expert opinion to quantify and rank priorities.An iterative systematic Delphi expert elicitation approach was used to prioritize management factors for the reduction of foodborne pathogen contamination in tomato greenhouses in the US. A validated online survey addressing eight thematic areas (water management, workers, environment and greenhouse design, equipment sanitation, waste management, animal intrusion, traceability, and propagation) was discussed among 20 individuals internationally recognized as experts in fresh produce production in protected agriculture, foodborne pathogens, and food safety theory and practice. Consensus rankings of activities and practices most likely contributing to microbial contamination and its mitigation were determined.Food safety priorities to prevent contamination of greenhouse tomatoes, in order of significance (i.e, ranking scale, weighted average; 1 lowest, 5 highest), included handwashing (4.67), environmental controls (4.32), enforceable worker health policy (3.94), cleaning and sanitation of reusable plastic containers (3.94), reused retail-ready containers (3.89), and irrigation water testing for human pathogens (3.84) to prevent contamination of greenhouse tomato.The majority of experts indicated that contaminated greenhouse surfaces that are in contact (direct or indirect) with the fruits are important sources of pathogen transfer to fresh tomatoes, highlighting the need for environmental controls in greenhouses. Importance of adequate worker management practices including handwashing and health policy highlights the role of worker education in reducing the risks of foodborne outbreaks linked to greenhouse grown produce. This report illustrates the benefits of using Delphi approach to improve food safety in greenhouses. The provided priority list can be used by growers to guide the routine food safety practice implementation procedures.