Application of a novel antimicrobial coating on roast beef for inactivation and inhibition of Listeria monocytogenes during storage

The antilisterial efficacy of novel coating solutions made with organic acids, lauric arginate ester, and chitosan was evaluated in a three-stage study on inoculated roast beef for the first time. Ready-to-eat roast beef was specially ordered from the manufacturer. The meat surface was inoculated with five-strain Listeria monocytogenes cocktail inoculums at two different levels, ~3 and 6LogCFU/cm2 and treated with the stock solution (HAMS), the 1:5 diluted solution (MAMS), and the 1:10 diluted solution (LAMS) (stage 1). During the 20min contact time, the antimicrobial coatings reduced the Listeria populations by approximately 0.9–0.3LogCFU/cm2. The higher the concentrations of the antimicrobial solution, the better the antilisterial effects were. The treated inoculated beef samples were then stored at 4°C for 30days. During storage, Listeria growth inhibition effects were seen. While no growth was seen from the HAMS-treated samples, a 1.6LogCFU/cm2 increase was seen for MAMS-treated samples, a 4.6LogCFU/cm2 increase was seen for LAMS-treated samples, and a 5.7LogCFU/cm2 increase was seen for NoAMS-treated samples on Day 30 (~3LogCFU/cm2 inoculation level). In the second stage, the impact of the roast beef storage time on solution's antilisterial effect was evaluated. Results showed that the effect of the antimicrobial solution was dependent on both the initial inoculation levels and storage times. In stage 3, the effect of the antimicrobial solution on roast beef quality was studied with both instrument measurement and sensory evaluation. Minor changes in color, pH, and water activity were found. However, only limited sensory differences were seen between the treated and untreated samples. When panels were able to accurately find color differences between samples, they preferred the treated samples. The findings of this research proved the antilisterial efficacy of the novel antimicrobial solution and showed its potential for being used as a roast beef cut surface coating to control Listeria contamination and for color protection.