Postharvest Biology and Technology 85 (2013) 1–7 Contents lists available at SciVerse ScienceDirect Postharvest Biology and Technology jou rn al h om epage: www.elsevier.com/locate/postharvbio Low dose UV-C illumination as an eco-innovative disinfection system on minimally processed apples Ana Grac ¸ a a , Miguel Salazar a,b , Célia Quintas c , Carla Nunes a,∗ a ICAAM, Universidade do Algarve, FCT, Ed 8, Campus de Gambelas, 8005-139 Faro, Portugal b CICAE, Instituto Universitário Dom Afonso III, INUAF, 8100-718 Loulé, Portugal c CIQA, Universidade do Algarve, IST, Campus da Penha, 8005-139 Faro, Portugal a r t i c l e i n f o Article history: Received 25 January 2013 Accepted 21 April 2013 Keywords: Escherichia coli Fresh-cut fruit Foodborne pathogens Listeria innocua Salmonella enterica a b s t r a c t In this study, the efficacy of UV-C illumination for inactivate Escherichia coli, Listeria innocua or Salmonella enterica, individually or in a mixture, in vitro and on apple slices was determined. Apple slices inoculated with a 10 7 cfu/mL suspension of above indicated pathogens were irradiated on both sides with UV-C illu- mination, with doses of 0.5 and 1.0 kJ/m 2 . UV-C illumination disinfection efficacy was compared to that of washings with sodium hypochlorite at 100 ppm of free chlorine and with distilled water. Bactericidal activity of each treatment was assessed after 30 min and after 7 and 15 days of storage at 4 ◦ C. Results showed that UV-C illumination at 1.0 kJ/m 2 could be an alternative to the wash with hypochlorite solu- tions. On the in vitro study, these doses completely inhibited the growth of the three bacteria either as pure cultures or in a mixture. In fresh-cut apple, the pathogens were also affected by the UV-C illumina- tion, the 1.0 kJ/m 2 dosage being the one that resulted in higher bacteria inhibition in almost every case. The UV-C treatment did not affect the quality properties of fresh-cut apple. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Consumption of fresh produce has increased over recent years, due to a tendency of adopting healthier food habits, and has led to the appearance of minimally processed (fresh-cut) products that are ready-to-eat. However, this growing demand raises the need for increase shelf-life and safety of these products. Fresh produce can be a vehicle for the transmission of foodborne pathogens, since they can be easily contaminated with microorganisms during pro- duction and processing. Contamination levels after harvesting can range from 3 to 7 log units, depending on the season and type of product (Ölmez and Kretzschmar, 2009). In recent years, the number of outbreaks of human infections associated with the consumption of minimally processed products and unpasteurized fruit juices has increased. The major concerns are with enteric pathogens such as Escherichia coli O157:H7 and Salmonella spp. that have fast growth rates and low infectious doses (Martin, 2007). Salmonellosis and E. coli O157:H7 infection have been linked to watermelon, tomatoes, seed sprouts, melons, apple or orange juice (Blostein, 1993; del Rosario and Beuchat, 1995; Beuchat, 1996; Butler, 2000; Krause et al., 2001; Greene et al., ∗ Corresponding author. Tel.: +351 289800900x7411; fax: +351 289818419. E-mail addresses: amgraca@ualg.pt (A. Grac ¸ a), miguel.salazar@agro-on.pt (M. Salazar), cquintas@ualg.pt (C. Quintas), carla.nunes@agro-on.pt, canunes@ualg.pt (C. Nunes). 2008; Munnoch et al., 2009; Muranyi, 2012). Furthermore, listerio- sis remains a great public health concern, as it has one of the highest case fatality rates of all the foodborne infections in Europe (20–30%) (Martin, 2007). The increase in reported outbreaks related to fresh fruit and vegetables may be the result of several causes. The per capita consumption of fresh produce has increased in developed countries. The demand for fresh produce year-round implies an increase in imports of these products from countries with different hygienic and sanitary conditions as well as the introduction of other pathogens (Lynch et al., 2009). Changes in processing, with more in-field cutting, coring and packaging, changes in the distribution systems, pathogens with different level of virulence, immunologi- cal changes among population segments and global trade, could be other reasons for the increase in outbreaks. Fresh-cut fruit are more susceptible to foodborne pathogens because their natural barriers are removed. Several studies have demonstrated that E. coli O157:H7, Salmonella spp. and Listeria monocytogenes could survive and/or grow in a range of minimally processed fruit such as apples (Dingman, 2000; Alegre et al., 2010a), honeydew melon (Leverentz et al., 2001, 2003), peaches (Alegre et al., 2010b), melon and pineapple (Abadias et al., 2012) and oranges (Lourenc ¸ o et al., 2012) at temperature of 10 ◦ C or higher. Washing fresh-cut products with sanitizing solutions is the only step in which a reduction of microbial contamination can be achieved (Allende et al., 2009; Ölmez and Kretzschmar, 2009). Chlo- rine (sodium hypochlorite solution, 50–200 mg/L for 1–2 min) is the most common sanitizer used in fresh-cut industry (Beuchat, 1998). 0925-5214/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.postharvbio.2013.04.013