Efficacy of freezing, frozen storage and edible antimicrobial coatings used in combination for control of Listeria monocytogenes on roasted turkey stored at chiller temperatures Zheng Jiang, Hudaa Neetoo, Haiqiang Chen * Department of Animal and Food Sciences, 020 Townsend Hall, University of Delaware, Newark, DE 19716-2150, USA article info Article history: Received 30 March 2011 Received in revised form 21 June 2011 Accepted 22 June 2011 Available online 29 June 2011 Keywords: Listeria monocytogenes Edible coating Antimicrobials Frozen storage Chilled storage Roasted turkey abstract The presence and growth of Listeria monocytogenes on ready-to-eat (RTE) turkey is an important food safety issue. The antilisterial efficacy of four polysaccharide-based edible coatings (starch, chitosan, alginate and pectin) incorporating sodium lactate (SL) and sodium diacetate (SD) as well as commercial preparations Opti.Form PD4, NovaGARDÔ CB1, Protect-M and GuardianÔ NR100 were compared against L. monocytogenes on roasted turkey. Pectin coating treatments incorporating SL/SD, Opti.Form PD4 with or without Protect-M, and NovaGARDÔ CB1 displayed higher antimicrobial efficacy against. L. monocytogenes than the other antimicrobials and coating materials. In the second phase of the study, it was investigated whether frozen storage could enhance the antilisterial effectiveness of pectin coating treatments on chilled roasted turkey. Inoculated roasted turkey samples coated with pectin-based treatments were frozen for up to 4 weeks and subsequently stored at 4  C for 8 weeks. Frozen storage significantly enhanced the antilisterial activity of various coating treatments; with selected treatments reducing the L. monocytogenes populations by as much as 1.1 log CFU/cm 2 during the subsequent 8-week chilled storage. This study demonstrates that pectin-based antimicrobial edible coatings hold promise in enhancing the safety of RTE poultry products and frozen storage has the potential to enhance their effectiveness. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Ready-to-eat (RTE) delicatessen turkey is in high demand by U.S. consumers. Unfortunately, these vacuum packaged chilled products with extended shelf-life can present a concern with respect to supporting the survival and growth of facultatively anaerobic psychrotrophic pathogens in this type of product. Listeria mono- cytogenes is one of these kinds of pathogens that can result in foodborne infections with symptoms ranging from a mild non- invasive listerial gastroenteritis to severe and sometimes life- threatening invasive listeriosis (CFSAN, 2003, CFSAN, 2008). According to recent estimates by the Centers for Disease Control and Prevention (CDC), there are at least 1591 cases of listeriosis with 255 deaths per year in the U.S. (Scallan et al., 2011), making it a significant public health concern. Since May 2000, there have been at least three high-profile listeriosis outbreaks that have been documented in the United States that were associated with the consumption of delicatessen-sliced turkey breast (Gottlieb et al., 2006). Ojeniyi et al. (1995) mentioned that L. monocytogenes iso- lated from a turkey processing plant, from the finished products and from clinical isolates may have also posed a high risk of infection for susceptible individuals and may have been the cause of the major outbreaks of ready-to-eat turkey products with L. monocytogenes (CDC 1999, 2000, 2002). In addition, it is thought that the inherent product characteristics of processed uncured turkey meat render them particularly susceptible to contamination and supportive of growth of L. monocytogenes. Indeed, Lianou et al. (2007) showed that the fate of L. monocytogenes in uncured turkey breast during simulated home storage (7  C) depended not only on the contamination scenario but also on the intrinsic properties of the product. Cross-contamination of RTE foods can occur at any time during the production and retailing stage (Aguado et al., 2001; Van Coilie, 2004). However, risk assessment data have shown that measures of control that prevent the occurrence of high levels of L. monocytogenes in food at the time of consumption will likely have the greatest impact on reducing the risk of contracting listeriosis (Norrung, 2000; Chen and Hoover, 2003). Food Safety and Inspection * Corresponding author. Tel.: þ1 302 831 1045; fax: þ1 302 831 2822. E-mail address: haiqiang@udel.edu (H. Chen). Contents lists available at ScienceDirect Food Microbiology journal homepage: www.elsevier.com/locate/fm 0740-0020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.fm.2011.06.015 Food Microbiology 28 (2011) 1394e1401