The effect of pore size on the diffusion of volatile antimicrobials is a key factor to preserve gelled foods

•Carvacrol diffusion and antimicrobial activities were studied in whey protein-carrageenan gels.•Carvacrol diffusion depends on the microstructural properties of gels.•Increased height of gels decreased carvacrol concentrations.•Weak activity of carvacrol in the interior of gels due to the low concentration. This study aimed to understand how the microstructure of gelled foods impacts the diffusion of a volatile antimicrobial compound and its efficacy at different depths from the surface. Carvacrol-loaded polylactic acid film was used to inhibit the growth of Pseudomonas fluorescens in WPI-carrageenan gels during storage at 4 °C. The diffusion of antimicrobials was increased in gels having larger average pore size. The antimicrobial efficacy of the antimicrobial packaging was dependent on the diffusion of carvacrol within the gels. The final concentration of carvacrol in the top layer was more than 4 fold higher than that in the middle layer and more than 13-fold higher than that in the bottom layer, resulting in a more effective inhibition in the top layer than those in the middle and bottom layers. Our study demonstrates the importance of considering the diffusion of antimicrobials in solid/semi-solid foods in the antimicrobial packaging design.