Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro UV-C inactivation of foodborne bacterial and viral pathogens and surrogates on fresh and frozen berries Sophie Butot a , Frédérique Cantergiani a , Mireille Moser a , Julie Jean b , Anthony Lima a , Lise Michot a , Thierry Putallaz a , Thomas Stroheker a , Sophie Zuber a, ⁎ a Nestlé Research Center, Institute of Food Safety and Analytical Science, CH 1000, Lausanne 26, Switzerland b Institute of Nutrition and Functional Foods, Université Laval, Quebec, Quebec G1V 0A6, Canada ARTICLE INFO Keywords: Inactivation Ultraviolet Food Berries Bacteria Virus ABSTRACT Outbreaks of foodborne illness associated with berries often involve contamination with hepatitis A virus (HAV) and norovirus but also bacteria such as Escherichia coli O157:H7 and parasites such as Cyclospora caytanensis. We evaluated the applicability of UV-C to the inactivation of pathogens on strawberries, raspberries and blueberries. Our three-step approach consisted of assessing the chemical safety of UV-C-irradiated berries, evaluating the sensory quality after UV-C treatment and finally studying the inactivation of the target microorganisms. Treatments lasting up to 9 min (4000 mJ cm -2 ) did not produce detectable levels of furan (< 5 μg/kg), a known photolysis product of fructose with genotoxic activity and thus were assessed to be toxicologically safe. No effect on taste or appearance was observed, unless treatment was excessively long. 20 s of treatment (an average fluence of ~ 212 mJ cm -2 ) reduced active HAV titer by > 1 log 10 unit in 95% of cases except on frozen rasp- berries, while 120 s were required to inactivate murine norovirus to this extent on fresh blueberries. The mean inactivation of HAV and MNV was greater on blueberries (2–3 log 10 ) than on strawberries and raspberries (< 2 log 10 ). MNV was more sensitive on fresh than on frozen berries, unlike HAV. Inactivation of Salmonella, E. coli O157:H7 and Listeria monocytogenes was poor on all three berries, no treatment reducing viable counts by > 1 log 10 unit. In most matrices, prolonging the treatment did not improve the result to any significant degree. The effect was near its plateau after 20 s of treatment. These results provide insight into the effectiveness of UV-C irradiation for inactivating bacterial and viral pathogens and surrogates on fresh and frozen berries having different surface types, under different physical conditions and at different levels of contamination. Overall they show that UV-C as single processing step is unsuitable to inactivate significant numbers of foodborne pathogens on berries. 1. Introduction In its quest to continue to provide non-perishable foods that are of high quality in terms of enjoyment, nutrition and safety in post-in- dustrial society, the food industry faces a variety of emergent chal- lenges. According to estimates, 31 foodborne agents caused 600 million illnesses worldwide in 2010 (World Health Organization, 2015). Fruits and vegetables are recognized as a major source of disease outbreaks, and the potential sources of contamination in the supply chain at both the pre-harvest (in the field) and post-harvest stages are various. As reviewed previously (Berger et al., 2010), the use of contaminated water for irrigation or rinsing, application of inadequately composted manures or raw sewage, contact with insects, storage and processing are all possible sources of contamination. Freezing remains a wide- spread practice for increasing the convenience and shelf life of highly perishable products. Frozen fruits are widely distributed and used as ingredients in many foods such as cakes, yogurts and smoothies. The most common pathogens transmitted by fruits and vegetables are human noroviruses (40%), followed by Salmonella (18%), Escherichia coli O157:H7 (8%), Clostridium (6%), the hepatitis A virus (4%), Shigella (4%), Bacillus (3%) and Staphylococcus (3%) (Doyle and Erickson, 2008). Numerous outbreaks of hepatitis A virus (HAV) and norovirus have been reported in association with consumption of fresh or frozen fruits such as blueberries (Calder et al., 2003), strawberries (Bernard et al., 2014; Montaño-Remacha et al., 2014; Niu et al., 1992; Nordic outbreak investigation team, 2013), raspberries (Gaulin et al., 1999; Le Guyader et al., 2004; Pönkä et al., 1999) and pomegranate arils (Collier et al., 2014; Swinkels et al., 2014). Foodborne parasites have also been associated with outbreaks linked to berries, for example cyclosporiasis associated with raspberries (Herwaldt, 2000). The EFSA https://doi.org/10.1016/j.ijfoodmicro.2018.03.016 Received 13 October 2017; Received in revised form 13 February 2018; Accepted 20 March 2018 ⁎ Corresponding author. E-mail address: sophie.zuber@rdls.nestle.com (S. Zuber). International Journal of Food Microbiology 275 (2018) 8–16 Available online 26 March 2018 0168-1605/ © 2018 Published by Elsevier B.V. T