Assessment of irrigation water quality and microbiological safety of leafy greens in different production systems

Abstract

Foodborne disease outbreaks associated with fresh produce irrigated with contaminated water are a constant threat to consumer health. In this study, the impact of irrigation water on product safety from different food production systems (commercial to small-scale faming and homestead gardens) was assessed. Hygiene indicators (total coliforms, Escherichia coli), and selected foodborne pathogens (Salmonella spp., Listeria monocytogenes, and Escherichia coli O157:H7) of water and leafy green vegetables were analyzed. Microbiological parameters of all irrigation water (except borehole) exceeded maximum limits set by the Department of Water Affairs for safe irrigation water. Microbial parameters for leafy greens ranged from 2.94 to 4.31 log CFU/g (aerobic plate counts) and 1 to 5.27 log MPN/100g (total coliforms and E. coli). Salmonella and E. coli O157:H7 were not detected in all samples tested but L. monocytogenes was present in irrigation water (commercial and small-scale farm, and homestead gardens). This study highlights the potential riskiness of using polluted water for crop production in different agricultural settings. PRACTICAL APPLICATIONS : These results show that the microbial quality of surface water is deteriorating in different agricultural settings. This may be a possible preharvest source of contamination of leafy green vegetables, which may then constitute a health risk to consumers. The presence of Listeria monocytogenes along the food supply chain is a potential health risk if the pathogen proliferates leading to high quantities suitable for onset of listeriosis. The absence of Salmonella and Escherichia coli O157:H7 in the samples tested is an encouraging result. Food safety protocols should be extended to the informal sectors and homestead gardens.