Radiation (Gamma) Resistance and Postirradiation Growth of Listeria monocytogenes Suspended in Beef Bologna Containing Sodium Diacetate and Potassium Lactate

Abstract

Listeria monocytogenes, a psychrotrophic foodborne pathogen, is a frequent postprocessing contaminant of ready-to-eat (RTE) meat products, including frankfurters and bologna. Ionizing radiation can eliminate L. monocytogenes from RTE meats. When they are incorporated into fine-emulsion sausages, sodium diacetate (SDA) and potassium lactate (PL) mixtures inhibit the growth of L. monocytogenes. The radiation resistance of L. monocytogenes, and its ability to proliferate during long-term refrigerated storage (9 degrees C), when inoculated into beef bologna that contained 0% SDA-0% PL, 0.07% SDA-1% PL, and 0.15% SDA-2% PL, were determined. The radiation doses required to eliminate 90% of the viable L. monocytogenes cells were 0.56 kGy for bologna containing 0% SDA-0% PL, 0.53 kGy for bologna containing 0.07% SDA-1% PL, and 0.46 kGy for bologna containing 0.15% SDA-2% PL. L. monocytogenes was able to proliferate on bologna containing 0% SDA-0% PL during refrigerated storage, but the onset of proliferation was delayed by the addition of the SDA-PL mixtures. An ionizing radiation dose of 3.0 kGy prevented the proliferation of L. monocytogenes and background microflora in bologna containing 0.07% SDA-1% PL and in bologna containing 0.15% SDA-2% PL over 8 weeks of storage at 9 degrees C. Little effect on lipid oxidation and color of the control bologna, or bologna containing SDA-PL mixtures, was observed upon irradiation at either 1.5 or 3.0 kGy.

Physical Methods for Cleaning and Disinfection of Surfaces

“…Similar results were observed for fruits [136][137][138] and pine kernels [139]. Shelf life extension and inactivation of pathogens require doses of 2.5-5 kGy for meat products, leading to inactivation rates of approximately five orders of magnitude for ready-to-eat foods (ham, frankfurters, chicken breast) [140][141][142]. Shelf life of poultry was extended from 6-10 to 12-20 days after 2.5 kGy radiation by Molins [143], and a three orders of magnitude viable count reduction was achieved for frozen (3-5 kGy) and chilled (1.5-2.5 kGy) poultry without loss of sensory quality [144,145].…”

“…Farkas [130] presented irradiation thresholds, which lead to an off-flavor of several meats; these thresholds ranged between 1.5 kGy for turkey and 6.5 for horse when treated at 5-10°C. It has also been shown that the addition of preservatives (e.g., sodium diacetate, potassium lactate) to a food allows the reduction of radiation intensity without affecting shelf life [140,162]. Hazards are radiation liberation and ozone formation.…”

Optimization of E-beam irradiation treatment to eliminate Listeria monocytogenes from ready-to-eat (RTE) cooked ham

“…So, from the data of Mendonca, Romero, Lihono, Nannapaneni and Johnson (2004) D-values of 0.41 and 0.65 kGy may be deduced for normal and starved cells of the strain Scott A suspended in physiological saline solution and 0.301-0.648 kGy (Grant & Patterson, 1992) and 0.16-0.38 kGy (Dion, Charbonneau, & Thibault, 1994) for several strains of L. monocytogenes. In meat products, D-values of 0.49 kGy in broiler at 12°C (Patterson, 1989) and 0.56 kGy in inoculated bologna (Sommers, Fan, Niemira, & Sokorai, 2003) have been reported.…”

Antimicrobial activity of lactic acid bacteria against Listeria monocytogenes on frankfurters formulated with and without lactate/diacetate

“…Combinations of the two are typically included in frankfurter emulsion and are effective in inhibiting pathogen growth at 4°C, and will delay growth at a mild abuse temperature of 10°C (Mbandi & Shelef, 2001;Seman, Borger, Meyer, Hall, & Milkowski, 2002;Sommers, Fan, Niemira, & Sokorai, 2003). However, consumers increasingly perceive chemicals in foods as severe, unknown, and unobservable hazards (Siegrist, Keller, & Kiers, 2005, 2006Sparks & Shepherd, 1994).…”