Efficacy of Sorbate and Benzoate in Controlling the Growth of Listeria monocytogenes on Meat Surface

Introduction: Treating the surface of meat products with antimicrobials to control surface-contaminated L. monocytogenes is an alternative measure to adding the antimicrobials into meat products. While many organic acids are frequently used for surface treatment of meat, sorbate and benzoate are GRAS antimicrobials primarily used in foods and beverages as antifungal agents.

Purpose: This study examined the efficacy of sorbate and benzoate at acidic pH in controlling L. monocytogenes on the surface of cooked meat.

Methods: A 5-strain mixture of L. monocytogenes was inoculated onto cooked ham slices to a level of approximately 3.0 log CFU/g. Inoculated samples were exposed to 0% (control), 2%, and 4% potassium sorbate or benzoate solutions adjusted with lactic acid to pH 4, 5, and 6 for 30 min, vacuum-packaged, and stored at 4°C for up 56 days. 

Results: The lag phase durations (LPDs) of L. monocytogenes in control samples treated with pH 4, 5, and 6 solutions were <4 days and the growth rates (GRs) were 0.11, 0.18 and 0.19 log/day, respectively.  L. monocytogenes was not able to grow in samples treated with 2% or 4% sorbate solution of pH 4, whereas the LPDs were >6 days and the GRs were 0.11 and 0.04 log/day in samples treated with 2% and 4% sorbate solutions of pH 5, respectively. Generally, sorbate was more effective than benzoate in controlling the growth of L. monocytogenes on cooked ham. Treatments with sorbate solutions of pH 4 and 5 were more effective in extending LPDs and reducing GRs of L. monocytogenes than acid solutions, whereas benzoate was more effective at pH 4.  

Significance: Results suggest a potential use of sorbate or benzoate solutions at acidic pH as a surface treatment to control the growth of contaminated L. monocytogenes on meat surface, thereby enhancing the microbiological safety of meat products.