title: Effect of Acidified Sorbate Solutions on the Lag-Phase Durations and Growth Rates of Listeria monocytogenes on Meat Surfaces.
abstract: The surfaces of ready-to-eat meats are susceptible to postprocessing contamination by Listeria monocytogenes. This study quantified the lag-phase durations (LPD) and growth rates (GR) of L. monocytogenes on the surfaces of cooked ham as affected by sorbate solutions of different concentrations and pH levels. Slices of cooked ham inoculated with a four-strain mixture of L. monocytogenes (ca. 10(3) CFU/g) were surface treated with sorbate solutions of 0 to 4% (wt/vol) at pH 4.0 to 6.5, vacuum packaged, and stored at 4 to 12 °C for up to 45 days. The LPD and GR of L. monocytogenes were used to develop response surface models. The models estimated that the LPD of L. monocytogenes in samples treated with solutions of pH 4.0 to 5.5 (no sorbate) were 0 to 11 days and the GR were 0.25 to 0.36 log CFU/day, respectively, at 4 °C. With the treatments of 2 and 4% (wt/vol) sorbate solutions, the LPD were estimated to be extended to 2 to 26 days and 34 to >45 days, and the GR were reduced to 0.15 to 0.30 and 0 to 0.19 log CFU/day, respectively. At 4 °C, increasing sorbate concentrations by 1% (wt/vol) to 2, 3, and 4% (wt/vol) at pH 5.5 to 4.0 led to an extension of LPD by 2 to 11, 10 to 19, and 18 to 27 days, whereas the GR were reduced by 0.037 to 0.055, 0.048 to 0.066, and 0.060 to 0.078 log CFU/day, respectively. Sorbate also extended the LPD and reduced the GR of L. monocytogenes at 8 and 12 °C. Results indicated that sorbate concentration and pH level were significant factors affecting the LPD and GR of L. monocytogenes and that the combination of sorbate and low pH has potential for use as a surface treatment to control L. monocytogenes on meat surfaces.
authors.affiliation: Residue Chemistry and Predictive Microbiology Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA. andy.hwang@ars.usda.gov.
authors.forename: Cheng-An
authors.initials: CA
authors.lastname: Hwang
authors.affiliation: Residue Chemistry and Predictive Microbiology Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Lihan
authors.initials: L
authors.lastname: Huang
authors.affiliation: Residue Chemistry and Predictive Microbiology Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Vijay
authors.initials: V
authors.lastname: Juneja
mesh_terms: D015169:Colony Count, Microbial; D004305:Dose-Response Relationship, Drug; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology / Q000379:methods*; D005519:Food Preservation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000254:growth & development; D008460:Meat / Q000382:microbiology*; D012996:Solutions; D013011:Sorbic Acid / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D014618:Vacuum
chemical_list: D012996:Solutions; D013011:Sorbic Acid