title: Growth of Listeria monocytogenes in different retail delicatessen meats during simulated home storage.
abstract: Delicatessen meats are reported to be the leading vehicle of foodborne listeriosis in the United States. Listeria monocytogenes can reach high numbers in these products during storage, and the growth rate is largely dictated by product formulation and storage temperature. To  assess the impact of product age on Listeria growth, five commercial brands each of cured and uncured turkey breast, ham, and roast beef (three lots per brand) were sliced (approximately 25 g per slice) at the beginning of the shelf life, the midpoint, and the last allowable day of  sale, surface inoculated with an eight-strain cocktail of L. monocytogenes (approximately 40 CFU/g), and then quantitatively examined for Listeria, lactic acid bacteria, and mesophilic aerobic bacteria during aerobic storage at 4, 7, or 10°C. As expected, L. monocytogenes  grew faster in deli meats without rather than with Listeria inhibitors (lactate and/or diacetate) and at the highest storage temperature (10°C). Lag-phase durations for L. monocytogenes in deli meats with and without Listeria inhibitors were 9.21, 6.96, and 5.00 and  6.35, 3.30, and 2.19 days at 4, 7, and 10°C, respectively. Generation times for L. monocytogenes in deli meats with and without Listeria inhibitors were 1.59, 1.53, and 0.85 and 0.94, 0.50, and 0.36 at 4, 7, and 10°C, respectively. Maximum population densities for L.  monocytogenes in deli meats with and without Listeria inhibitors were 5.26, 5.92, and 5.97 and 8.47, 8.96 and 9.34 log CFU/g at 4, 7, and 10°C, respectively. Although lactate and diacetate suppressed L. monocytogenes growth, the extent of inhibition differed, ranging  from total inhibition in roast beef to only partial inhibition in ham and cured turkey. Listeria growth was also impacted by lot-to-lot variation in the concentrations of Listeria inhibitors, product pH, and background microflora. These data will be useful for developing recommendations  for "best consumed by" dating for deli meats using a risk-based approach.
authors.affiliation: Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Scott R
authors.initials: SR
authors.lastname: Moosekian
authors.forename: Ewen C D
authors.initials: EC
authors.lastname: Todd
authors.forename: Elliot T
authors.initials: ET
authors.lastname: Ryser
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000818:Animals; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D005506:Food Contamination / Q000032:analysis; D005511:Food Handling / Q000379:methods*; D005519:Food Preservation / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007773:Lactates / Q000494:pharmacology; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development* / Q000302:isolation & purification; D008461:Meat Products / Q000382:microbiology*; D018570:Risk Assessment; D013696:Temperature
chemical_list: D000085:Acetates; D007773:Lactates