Potential for Natural Antimicrobials, Including Mushroom Chitosan, to Control Shiga‐Toxigenic <scp> <i>Escherichia coli</i> </scp> in Ground Beef

ABSTRACT Shiga‐toxigenic Escherichia coli (STEC) is a pathogen commonly shed in the feces of bovine animals, and beef and beef products are at high risk of contamination during slaughter and processing operations. This study investigated the potential application of a range of natural antimicrobials to control STEC in ground beef (beef burgers) during chilled vacuum pack storage. Initially, the Minimum Inhibitory and Bactericidal Concentrations (MIC and MBC) of a range of natural antimicrobials ( n = 11) against a range of STEC serotypes ( n = 8) at different pH (4.5, 7.3) and temperatures (37°C, 4°C) conditions was determined. The agents ( n = 5) demonstrating the best results were chitosan from shrimp and mushroom, cranberry extract, carvacrol, and thyme EO. These were then further tested for their efficacy against E. coli O157 inoculated at approximately 3.7 log 10 CFU g −1 into ground beef burgers packed under vacuum and stored at 3°C ± 1°C for up to 16 days. Mushroom chitosan (1.25%) and shrimp chitosan (2.5%) exhibited the highest bactericidal activity against E. coli O157 in beef burgers, yielding a 2 and 1.94 log 10 CFU g −1 ( p &lt; 0.05) reduction of the pathogen compared to the control at the end of chilled storage period. Cranberry extract (2.5%) and carvacrol (0.2%) yielded lower reduction of 0.72 and 0.28 log 10 CFU g −1 ( p &lt; 0.05), respectively, in E. coli O157 by Day 16. Chitosan from mushrooms is a promising natural antimicrobial solution to manage STEC in ground beef.