Food Control 17 (2006) 981–986 www.elsevier.com/locate/foodcont 0956-7135/$ - see front matter  2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodcont.2005.07.007 Survival and growth of Listeria monocytogenes on sausage formulated with inoculated and stored rework product Hristo Daskalov a,¤ , Joe Momfre b , John N. Sofos b a Department of Hygiene, Technology and Control of Food and FoodstuVs, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria b Department of Animal Sciences, Colorado State University, Fort Collins, Colorado 80523-1171, USA Received 3 February 2005; received in revised form 14 July 2005; accepted 15 July 2005 Abstract To assess the eVect of including contaminated rework on survival and growth of Listeria monocytogenes, two sausage formula- tions (one American, Bologna sausage; and one Bulgarian, Stranja sausage) were inoculated with the pathogen and stored for 4 days at 10 °C plus 15 h at 30 °C. After storage, both rework types were included (at 20% and 40%) in corresponding fresh sausage emul- sions and heated to 68, 70 and 71.7 °C; fresh Bologna and Stranja emulsions served as controls and were inoculated with 24 h broth cultures of the same 10-strain mixture of L. monocytogenes and thermally treated to the same temperatures. The results showed that heating to 68 and 70 °C inactivated 3–4 log CFU/g of the initial concentration of L. monocytogenes cells (>7 log CFU/g), while heat treatment to 71.7 °C in the center of experimental samples reduced counts by 6 log CFU/g. Survival of L. monocytogenes in samples heated to 68 and 70 °C was higher in controls. Control samples of Stranja emulsion heated to 71.7 °C allowed higher growth (P < 0.05) during storage (5 days at 10 °C) as compared to other control and experimental rework samples. The Stranja emulsion had a higher fat content (20.2%) compared to the Bologna emulsion (11%). This study provides evidence about the possible danger when potentially contaminated rework is stored and then introduced into fresh product formulations.  2005 Elsevier Ltd. All rights reserved. Keywords: Listeria monocytogenes; Sausage; Rework 1. Introduction Listeria monocytogenes has been associated with human illness for more than 70 years, but only during the last two decades has it been recognized as an important foodborne pathogen. Disease caused by L. monocytogenes is mostly associated with consumption of ready-to-eat products. According to data of the United States Centers for Disease Control and Prevention (CDC) (Mead et al., 1999), listeriosis illnesses and deaths in the USA are estimated at 2500 and 500, respectively. The US Food and Drug Administration (FDA) and the US Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) have established a “zero tolerance” policy under which ready-to-eat foods con- taminated with detectable levels of L. monocytogenes are deemed adulterated. Thus, L. monocytogenes is consid- ered as an “adulterant” and any ready-to-eat food that contains this microorganism (in a 25 g sample) is subject to a Class I recall and/or seizure in the USA (Harris, 2002). Tompkin (2002) noted that despite eVorts to eradi- cate the pathogen from ready-to-eat foods, L. monocyt- ogenes contamination continues to occur. Levine, Rose, Green, Ransom, and Hill (2001) reported up to 5% con- tamination of some ready-to-eat foods with L. monocyt- ogenes. L. monocytogenes was also the primary cause of food recalls due to biological reasons (35 of 39 recalls of * Corresponding author. Tel.: +359 42 699537; fax: +359 42 670624. E-mail address: hdaskal@uni-sz.bg (H. Daskalov).