Inhibition of Listeria monocytogenes by Propionic Acid–Based Ingredients in Cured Deli-Style Turkey

Abstract

Listeria monocytogenes growth can be controlled on ready-to-eat meats through the incorporation of antimicrobial ingredients into the formulation or by postlethality kill steps. However, alternate approaches are needed to provide options that reduce sodium content but maintain protection against pathogen growth in meats after slicing. The objective of this study was to determine the inhibition of L. monocytogenes by propionic acid-based ingredients in high-moisture, cured turkey stored at 4 or 7°C. Six formulations of sliced, cured (120 ppm of NaNO2 ), deli-style turkey were tested, including control without antimicrobials, 3.2% lactate-diacetate blend (LD), 0.4% of a liquid propionate-benzoate-containing ingredient, or 0.3, 0.4, and 0.5% of a liquid propionate-containing ingredient. Products were inoculated with 5 log CFU L. monocytogenes per 100-g package (3 log CFU/ml rinsate), vacuum-sealed, and stored at 4 or 7°C for up to 12 weeks; and populations were enumerated by plating on modified Oxford agar. As expected, the control without antimicrobials supported rapid growth, with >2 log average per ml rinsate increase within 4 weeks of storage at 4°C, whereas growth was observed at 6 weeks for the LD treatment. For both replicate trials, all treatments that contained liquid propionate or propionate-benzoate limited L. monocytogenes growth to an increase of <1 log through 9 weeks storage at 4°C. Sporadic growth (>1-log increase) was observed in individual samples for all propionate-containing treatments at weeks 10, 11, and 12. As expected, L. monocytogenes grew more rapidly when products were stored at 7°C, but trends in relative inhibition were similar to those observed at 4°C. These results verify that propionate-based ingredients inhibit growth of L. monocytogenes on sliced, high-moisture, cured turkey and can be considered as an alternative to reduce sodium-based salts while maintaining food safety.

Combined Effect of Organic Acids and Modified Atmosphere Packaging on Listeria monocytogenes in Chicken Legs

“…Our results suggest that in high CO 2 environments, organic acids might act synergistically to reduce the growth of L. monocytogenes . The efficacy of organic acids and MAP in L. monocytogenes control in meat and poultry has been also pointed out by other authors [ 7 , 39 , 40 , 41 ]. The effect of lactic acid and MAP on L. monocytog enes in chicken was investigated by Zeitoun and Debevere [ 7 ].…”

Listeria monocytogenes Response to Propionate Is Differentially Modulated by Anaerobicity

“…Propionate is a Generally Recognized As Safe (GRAS) antimicrobial and flavoring agent [ 3 ] and its antimicrobial function against L. monocytogenes is under active investigation. Among the variety of food products that have been tested, such as ready-to-eat meat [ 4 , 5 , 6 ], raw poultry [ 7 ], and produce [ 8 , 9 ], propionate exhibited anywhere from no effect [ 7 , 8 ] to a significant growth inhibitory effect [ 4 , 5 ]. While the exact conditions required for propionate to inhibit L. monocytogenes growth are not clear in food products, it was shown that the presence of propionate at concentrations as little as 4 mM could decrease L. monocytogenes in vitro growth in rich media [ 10 , 11 ].…”

Comparative Efficacy of Potassium Levulinate with and without Potassium Diacetate and Potassium Propionate versus Potassium Lactate and Sodium Diacetate for Control of Listeria monocytogenes on Commercially Prepared Uncured Turkey Breast

“…Glass et al (10) also reported that inclusion of 0.2 or 0.3% sodium propionate supported a < 1.0-log increase of L. monocyto genes in ham and uncured turkey breast over 120 days of storage at 4°C. More recently, Glass et al (11) reported that inclusion of sodium propionate at 0.3, 0.4, or 0.5% in cured turkey breast precluded growth of L. monocytogenes (< 1.0log increase) during 63 days of storage at 4°C when compared with otherwise similar samples formulated without antimicrobials.…”

“…In general, the efficacy of growth inhibitors for reducing the risk and occurrence of L. monocytogenes could be affected by meat type (i.e., poultry versus pork), intrinsic characteristics of the product (e.g., pH, water activity, moisture, or nitrite level), and concen tration of the antimicrobial and/or its dissociation constant (i.e., pKa) (5,11,30). For example, typical concentrations of lactate (1.5 to 3.0%) used alone or in combination with diacetate (0.125 to 0.25%) by meat processors are less effective for suppressing outgrowth of L. monocytogenes on uncured RTE meats than on cured RTE products (10,37), most likely because of the synergistic effect of nitrite and lactate-diacetate in the cured products.…”