Antimicrobial property and microstructure of micro-emulsion edible composite films against Listeria

- Edible antimicrobial composite films from micro-emulsions were developed.
- Composite films significantly inactivated Listeria in TSB and RTE meat.
- HPH treatment enhanced antimicrobial efficacy of films.

Edible antimicrobial composite films from micro-emulsions containing all natural compounds were developed and their antimicrobial properties and microstructures were investigated. Chitosan, allyl isothiocyanate (AIT), barley straw arabinoxylan (BSAX), and organic acids (acetic, lactic and levulinic acids) were used as film-forming agent, antimicrobial agent, emulsifier, and solvent, respectively. Micro-emulsions were obtained using high pressure homogenization (HPH) processing at 138 MPa for 3 cycles. The composite films made from the micro-emulsions significantly (p < 0.05) inactivated Listeria innocua in tryptic soy broth (TSB) and on the surface of ready-to-eat (RTE) meat samples, achieving microbial reductions of over 4 log CFU/ml in TSB after 2 days at 22 °C and on meat samples after 35 days at 10 °C. AIT was a major contributor to the antimicrobial property of the films and HPH processing further enhanced its antimicrobial efficacy, while the increase of chitosan from 1.5% to 3%, or addition of acetic acid to the formulations didn't result in additional antimicrobial effects. This study demonstrated an effective approach to developing new edible antimicrobial films and coatings used for food applications.