Purpose: The objective of this study was to develop new edible antimicrobial coating solutions and films using natural biopolymers and high pressure homogenization technology.
Methods: Allyl isothiocyanate (AIT, 5%), barley fiber gum (BFG, 0.5%) and chitosan (3%) were used as antimicrobial, emulsifier, and film former, respectively, and were mixed in an acid solution (2%). The mixture was treated by high pressure homogenization (HPH, 138 MPa, 3 cycles). The solution was vacuum dried to form an edible packaging film. Antimicrobial activities of the solution used alone or the films against Listeria innocua in tryptic soy broth (TSB) or on deli meat were investigated. Physical properties including transparency, color, and binding capacity on other plastic films were also evaluated. The release of AIT from solutions/films was determined by GC-MS method.
Results: Films with BFG were softer, less rigid and more stretchable than those without BFG. HPH treatment significantly (P < 0.05) reduced the particle sizes in the emulsion to less than 1 μm. Both BFG and HPH significantly reduced the pungent odor of AIT in films without losing its antimicrobial activity and enhanced the binding capability of the solutions on the plastic films. The films reduced L. innocua by up to 5 log CFU in TSB, and also significantly inhibited its growth on meat surface.
Significance: The developed method can be used for other pungent essential oils. This study provides an innovative approach to develop edible antimicrobial coating solutions and films to reduce potential microbial contaminations on foods, enhance food safety, and extend shelf life.