INVESTIGATION INTO THE LINK BETWEEN WATER QUALITY AND MICROBIOLOGICAL SAFETY OF SELECTED FRUIT AND VEGETABLES FROM FARMING TO PROCESSING STAGES (VOLUME 1) Report to the WATER RESEARCH COMMISSION and DEPARTMENT OF AGRICULTURE, FORESTRY AND FISHERIES Edited by EM du Plessis1 and L Korsten1 Research team L Korsten1, EM Buys2, B Pillay3, M Taylor4 1Department of Microbiology and Plant Pathology, University of Pretoria 2Department of Food Science, University of Pretoria 3Department of Microbiology, University of KwaZulu-Natal 4Department of Medical Virology, University of Pretoria/National Health Laboratory Service WRC Report No. 1875/1/15 ISBN 978-1-4312-0693-3 August 2015 Obtainable from Water Research Commission Private Bag X03 GEZINA, 0031 [email protected] or download from www.wrc.org.za DISCLAIMER This report has been reviewed by the Water Research Commission (WRC) and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the WRC nor does mention of trade names or commercial products constitute endorsement or recommendation for use. © Water Research Commission ii EXECUTIVE SUMMARY Background and motivation An increase in the consumption of fresh and minimally processed fruits and vegetables globally (Ayers and Westcot, 1 985; Beuchat, 2002) has resulted in one of the most important health challenges in terms of foodborne diseases. In the United States of America (USA) these dietary changes resulted in doubling of produce-associated disease outbreaks per year from 1973-1992 (USA Food and Drug Administration, 1998). However, over the past 10-15 years the number of foodborne disease outbreaks has declined. The number of CDC outbreak reports varied between 1243 to 1417 during 2000-2002 in comparison to only 800 to 850 outbreaks reported from 2009-2013 (http://www.foodsafetynews.com/2015/06/the-prevalence-of-foodborne-illness; accessed 12 July 2015). Specific examples include three outbreaks in 2004 in the USA and Canada due to Salmonella, affecting 561 people who consumed fresh tomatoes [Centres for Disease Control and Prevention (CDC), 2005]. In 2006 another outbreak was associated with the consumption of tomatoes, with 183 cases being reported in 21 states (CDC, 2006a). Subsequently, a Salmonella outbreak, occurring from April to August 2008 in the USA, was linked to the consumption of raw tomatoes, jalapeno and cilantro. This multi-state outbreak affected 1438 people with 282 people needing hospitalisation and possibly contributing to the deaths of two people (CDC 2008a). In 2008 a second outbreak was associated with cantaloupe. This affected 51 people in 16 states, with 16 people hospitalised (CDC 2008b). Major disease outbreaks have also been associated with other pathogens such as Escherichia coli O157:H7, which affected 183 people in the USA in September 2006. Of these, 95 people were hospitalised, 29 people had haemolytic uremic syndrome and one person died (CDC 2006b). This outbreak was linked to the consumption of fresh bagged spinach. Additionally, a more recent multistate outbreak of E. coli O157:H7 in 2011 in 10 states of the United States caused 60 individuals to become ill (http://www.cdc.gov/ecoli/2011/ecoliO157/romainelettuce/120711/index.html; accessed 2015 June 25). A foodborne disease outbreak in the European Union in May 2011 was caused by E. coli O104:H4, a more virulent verocytotoxin-producing strain than E. coli O157:H7. The outbreak was eventually linked to a German sprout producer after first implicating Spanish cucumbers and tomatoes. The resultant €225 million losses per week of Spanish vegetable producers highlighted the economic impact of these outbreaks and the importance of accurate diagnostic test methods (http:// www.bbc.co.uk/news/world-europe-13683270; accessed 2015 June 25). A Listeriosis outbreak during 2011 was reported to be due to consumption of contaminated cantaloupes that left 146 people ill and caused 30 deaths in 28 states across the United States (http://www.foodsafetynews.com/2011/10/Cantaloupe-listeria-outbreak-84- sick-15-dead; accessed 2015 June 25). According to the World Health Organisation about one third of 51 million deaths world-wide result from infectious and parasitic diseases. It has been estimated that worldwide 50 000 people die daily as a result of water-related diseases. Foodborne diseases due to food iii contamination may occur at any point along the food chain, from the farm through food processing to the end user. However, the majority of foodborne outbreaks have been traced to contamination on the farm and the use of contaminated water (Westcot, 1997; Beuchat, 2002). Several studies have investigated or reviewed the impact of contaminated irrigation water on the spread of foodborne diseases (Ayers and Westcot, 1985; FDA, 1998; Venter, 2001). Fresh produce is important from a national food supply and consumer health point of view while fresh fruit exports constitute a major part of the economy representing the third biggest earner of foreign exchange. South Africa has over the past 100 years built an international reputation as a major competitor in the export markets, delivering top quality and safe produce. South African farmers have further implemented measures to ensure compliance with new stringent good agricultural practices and food safety standards, allowing the country to remain a leading player in international food trade. Unprecedented challenges facing the quality and quantity of our national water supplies have resulted in a new risk for farmers reliant on irrigation of cultivated crops (Gemmel and Schmidt, 2012; Chigor et al., 2013). Studies solicited by the Water Research Commission (WRC) entitled: “Quantitative Investigation into the Link between Irrigation Water Quality and Food Safety” (WRC Report Number 1773/1-4/12) and “Health risk assessment in connection with the use of microbiologically contaminated source water for irrigation” (WRC Report Number 1226/1/04) have shown that the national water supplies are contaminated with pathogens and may pose a potential risk for the fresh fruit export industry and national safe food supplies. It was argued that a project that focuses on the risks in the supply chain will support and strengthen the findings in WRC Report Number 1773/1-4/12. Aims: The general and specific aims of this project were: 1. To investigate the links between water quality and microbiological safety in fresh minimally processed and frozen fruit and vegetables. 2. To review the literature study of WRC Report Number 1773/1-4/12 and expand the review to include a comprehensive literature study on processing water quality and its impact on the microbiological safety of food and potential effect on human health. 3. To establish co-operation with the team of researchers involved in WRC project K 5 / 1773/4. 4. To select appropriate sites, with reference to i) different sources of untreated and treated water (excluding greywater), ii) different types of microbial contamination, iii) different types of farming – subsistence, emerging, commercial farming for local and export markets, iv) different crops and produce (specifically fruit and vegetables), v) different pathways of contamination: water for irrigation and water used for sprays, and iv) different pathways of contamination: water as transport and washing medium as part of packing and processing. 5. To propose and standardise the research methodology for the assessment of the impact iv of contaminated irrigation water and processing water on microbial food safety. 6. To determine the extent (types and quantities) of contamination found in irrigation and processing water at the selected sites, with reference to i) indicators of water quality, ii) volume of water used for irrigation and processing, iii) microbial contaminants (viruses, bacteria, parasites), iv) physical parameters (pH, COD, EC, turbidity, temperature, etc.), and v) influence of personal on-site hygiene facilities vi) Influence of external quality control on food safety management at the farming and processing stages of production. 7. To investigate the impact of environmental parameters on the growth kinetics of contaminants, with reference to i) fate and survival, ii) decay rates, iii) surrogate organisms, and iv) different irrigation and processing technologies. 8. To study the extent of (types and quantities) contamination found on the irrigated raw produce (fruit and vegetables) up to harvest at selected sites, with reference to i) microbial contaminants (viruses, bacteria, parasites)m ii) microbial indicators/index of contamination/risk, iii) method of irrigation, agri-chemical spray water application, etc., and iv) investigate the potential link and/or association between contamination on raw produce and water applied (molecular epidemiology using a reference organism). 9. To study the extent (types and quantities) of contamination found on the raw produce (fruit and vegetables) after harvest, with reference to i) microbial contaminants (viruses, bacteria, parasites), ii) microbial indicators/index of contamination/risk, iii) additional contamination through handling, washing, storage, packaging, pre- freezing and minimal processing, etc., and iv) impact of biofilms in processing on product contamination. 10. To make interim and final recommendations for further research, with reference to: Further validation of results and Effective treatment options. Research Findings In this Volume the results for aims 2-7 (see page iii-iv) are reported on.