Control of Listeria monocytogenes in Processed Meat and Poultry by Combinations of Antimicrobials

This research followed up on previous research that demonstrated the effectiveness of antimycotic agents in controlling Listeria. The resulting data has been used to obtain provisional FSIS approval of sorbate, benzoate and propionate

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Objectives

The goal of this project was to identify combinations of food-approved antimicrobials that are inhibitory to Listeria monocytogenes in processed poultry and meat products.

Conclusions

LM did not grow in wiener or turkey slurries supplemented with 0.25% potassium sorbate, propionic acid, or benzoic acid when stored at either 4 or 10°C. Nisin alone (>50 ppm) reduced populations of LM by 1 to 1.5-log cfu/g within 10 minutes of inoculation, but resistant populations increased >3-log during the 4-week storage. Combining 50 ppm nisin and 0.3% diacetate prevented recovery of LM at 4 or 10°C in both meat types throughout the 4-week period. Certain treatments (0.1% sorbate, propionate, or benzoate, 0.5% commercial organic acid blend, 0.2% natural extract blend, 2.5% commercial lactatediacetate blend with 0.5% polyphosphates, and 0.1% diacetate-25 ppm nisin) prevented listerial growth in wiener slurries with 30 ppm nitrite, but not in uncured turkey slurries. 
Data revealed that 0.1% combined benzoate/propionate or benzoate/sorbate prevented growth of LM on cured bologna stored at 4°C for 91 days compared with > 3.5-log cfu/pkg increase in the control bologna without antimycotics. In contrast, processed turkey with 0.1% combined antimycotics supported a 2-log cfu/pkg increase in listerial populations at 2 weeks storage compared with a 4-log cfu/pkg increase in the control turkey during the same time period. These data suggest that antimycotic agents can prevent growth of L. monocytogenes in cured processed meats, but combined levels >0.15% may be required to prevent growth of the pathogen on uncured poultry.

Deliverable

Additional research is needed to verify the minimum antimicrobial levels required to prevent growth. Data from such studies will provide manufacturers with viable formulation options to inhibit growth of L. monocytogenes during refrigerated shelf-life.  Data collected for additional research can be used to petition USDA for approval for use of sorbate, benzoate, and propionate as antilisterial agents in RTE meats.