Hot Water Postprocess Pasteurization of Cook-in-Bag Turkey Breast Treated with and without Potassium Lactate and Sodium Diacetate and Acidified Sodium Chlorite for Control of Listeria monocytogenes
Abstract:Surface pasteurization and food-grade chemicals were evaluated for the ability to control listeriae postprocess on cook-in-bag turkey breasts (CIBTB). Individual CIBTB were obtained directly from a commercial manufacturer and surface inoculated (20 ml) with a five-strain cocktail (ca. 7.0 log) of Listeria innocua. In each of two trials, the product was showered or submerged for up to 9 min with water heated to 190, 197, or 205°F (ca. 87.8, 91.7, or 96.1°C) in a commercial pasteurization tunnel. Surviving listeriae were recovered from CIBTB by rinsing and were then enumerated on modified Oxford agar plates following incubation at 37°C for 48 h. As expected, higher water temperatures and longer residence times resulted in a greater reduction of L. innocua. A ca. 2.0-log reduction was achieved within 3 min at 205 and 197°F and within 7 min at 190°F. In related experiments, the following treatments were evaluated for control of Listeria monocytogenes on CIBTB: (i) a potassium lactate–sodium diacetate solution (1.54% potassium lactate and 0.11% sodium diacetate) added to the formulation in the mixer and 150 ppm of acidified sodium chlorite applied to the surface with a pipette, or (ii) a potassium lactate–sodium diacetate solution only, or (iii) no potassium lactate–sodium diacetate solution and no acidified sodium chlorite. Each CIBTB was inoculated (20 ml) with ca. 5 log CFU of a five-strain mixture of L. monocytogenes and then vacuum sealed. In each of two trials, half of the CIBTB were exposed to 203°F water for 3 min in a pasteurization tunnel, and the other half of the CIBTB were not; then, all CIBTB were stored at 4°C for up to 60 days, and L. monocytogenes was enumerated by direct plating onto modified Oxford agar. Heating resulted in an initial reduction of ca. 2 log CFU of L. monocytogenes per CIBTB. For heated CIBTB, L. monocytogenes increased by ca. 2 log CFU per CIBTB in 28 (treatment 1), 28 (treatment 2), and 14 (treatment 3) days. Thereafter, pathogen levels reached ca. 7 log CFU per CIBTB in 45, 45, and 21 days for treatments 1, 2, and 3, respectively. In contrast, for nonheated CIBTB, L. monocytogenes levels increased from ca. 5 log CFU per CIBTB to ca. 7 log CFU per CIBTB in 28, 21, and 14 days for treatments 1, 2, and 3, respectively. Lastly, in each of three trials, we tested the effect of hot water (203°F for 3 min) postprocess pasteurization of inoculated CIBTB on the lethality of L. monocytogenes and validated that it resulted in a 1.8-log reduction in pathogen levels. Collectively, these data establish that hot water postprocess pasteurization alone is effective in reducing L. monocytogenes on the surface of CIBTB. However, as used in this study, the potassium lactate–sodium diacetate solution and acidified sodium chlorite were only somewhat effective at controlling the subsequent outgrowth of this pathogen during refrigerated storage.
Document Type: Research Article
Affiliations: 1: Microbial Food Safety Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA 2: Professional Resource Organization, 1405 Irvine Drive, Edmund, Oklahoma 73003, USA