Evaluation of a novel antimicrobial solution and its potential for control Escherichia coli O157:H7, non-O157:H7 shiga toxin-producing E. coli, Salmonella spp., and Listeria monocytogenes on beef

Highlights

• A novel antimicrobial solution showed good antimicrobial results as a marinade.

• Marination time has an impact on the antimicrobial results.

• Antimicrobial results were dependent on the cocktails and the inoculation levels.

• The efficacy of the original concentration AMS is better than commercial marinades.

Abstract

The goal of this study was to evaluate the efficacy of a novel antimicrobial solution made with chitosan, lauric arginate ester, and organic acids on Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, and non-O157 shiga toxin-producing E. coli cocktails and to test its potential to be used as a marinade for raw beef. Fresh beef top round steaks were surface-inoculated with the pathogen cocktails at approximately 2.5 or 4.5 Log CFU/cm², marinated with the antimicrobial solution (AMS), and then stored at 4 °C for 6, 24, and 48 h. Three commercially available marinades were used for comparison. Results revealed that AMS had the most antimicrobial effect regardless of the type or inoculation level of pathogens (P < 0.05). After 6 h, the AMS marination reduced all pathogens to levels below the limit of detection (<1 Log CFU/cm²), resulting in a 3.5 Log CFU/cm² reduction. When AMS was diluted with autoclaved distilled water by 5 times (AMS 1:5) or 10 times (AMS 1:10), its antimicrobial efficacy was impacted by marination time, the inoculated pathogens, and the inoculation levels. This study demonstrates that the developed antimicrobial solution has a great potential to be used during marination by consumers to ensure better food safety.

Introduction

Foodborne pathogen involved outbreaks have been of public concern. Listeria and Salmonella (nontyphoidal) are pathogens that cause the most death according to the CDC (CDC., 2011). Escherichia coli O157:H7 has been one of the top five pathogens that contribute to domestically acquired foodborne illness resulting in hospitalization (CDC., 2011). In 2012, six additional shiga toxin producing E. coli serovars, including E. coli O26, O111, O103, O121, O45, and O145, were placed on the zero tolerance adulterant list (USDA., 2011).

Since 1993, the beef industry spent more than $420 million on beef safety research which generated a significant amount of information and usable best practices (Muras, Lucia, Hardin, Savell, & Harris, 2009). The development of novel antimicrobial solutions is one of the major achievements. Among those solutions, a novel antimicrobial solution made with generally recognized as safe (GRAS) antimicrobial compounds was first proposed to be used as a ready-to-eat turkey breast surface treatment in 2014 (Guo, Jin, Wang, Scullen, & Sommers, 2014). In 2015, Wang, Zhao, Yuan, and Jin (2015) evaluated its application on roast beef and their results showed that this antimicrobial solution made with chitosan, lauric arginate ester (LAE), and organic acids inhibited the growth of inoculated Listeria monocytogenes. The sensory evaluation conducted (Wang et al., 2015) showed that although a slightly bitter taste was noticed by panelists immediately after the application of the solution, panelists were not able to tell the difference between the treated and untreated samples after 15 days of storage. The proposed antimicrobial also had a color protective effect on roast beef. The treated samples had a fresher looking color than the untreated samples after 30 days of storage at 4 °C.

The goal of this study was to investigate the efficacy of the antimicrobial solution against foodborne pathogens, including E. coli O157:H7, Salmonella, L. monocytogenes, and non-O157 Shiga toxin-producing E. coli, and to evaluate its efficacy on fresh meat when using it as a meat marinade at 4 °C.

Marination of meat is an emerging industrial technique for improving meat tenderness, flavor and extending meat shelf life (Pathania, McKee, Bilgili, & Singh, 2010). Marination provides the opportunity to allow potential antimicrobial components to be in contact with pathogenic bacteria. Thus, marination becomes one food preparation step which not only adds product value but also provides an opportunity to achieve better food safety (Pathania et al., 2010). This study also used three commercially available marinades (a balsamic & roasted onion classic marinade, a lemon & cracked pepper marinade, and a classic steakhouse marinade) for comparison. The specific objectives of this study were to 1) determine the effectiveness of three concentrations of an antimicrobial solution used during marination at 4 °C, and 2) compare its antimicrobial effects with three retail marinades.