Antibacterial activity of soy edible coatings incorporated with thyme and oregano essential oils on beef against pathogenic bacteria.

Inhibitory effects of soy-protein edible coatings incorporated with 1, 2, or 3% of thyme or oregano essential oils (EOs) were determined against Escherichia coli O157:H7 (EC), Listeria monocytogenes (LM), and Staphylococcus aureus (SA) in vitro and on fresh beef during refrigerated storage for 14 days. The soy-protein coatings with oregano and thyme EOs exhibited similar antimicrobial activity against the test bacteria. Greater antimicrobial activity of soy edible coatings was demonstrated against SA when 3% of EOs were added. Coatings with 3% thyme and oregano EOs exhibited 2.86 and 2.59, 1.97 and 1.90, and 1.87 and 1.83 log CFU/g reductions in SA, LM, and EC populations, respectively, as compared with the control by Day 14. This study demonstrated that application of edible coatings containing oregano and thyme EOs on fresh beef cuts could have a potential for controlling pathogenic bacteria and enhancing color stability with acceptable sensory characteristics.