Zein films and coatings as carriers and release systems of Zataria multiflora Boiss. essential oil for antimicrobial food packaging

Zein films loaded with 5 or 10% of Zataria multiflora Boiss. essential oil (ZEO) were successfully obtained. Migration of antimicrobial carvacrol and thymol, major components of ZEO, was monitored at different temperatures and with different food simulants, and apparent diffusion was calculated. Antimicrobial properties of the films were assayed in vapour phase and liquid medium. The results showed that films containing 5% ZEO achieved reductions of 1.18 log and 1.14 log against L. monocytogenes and E. coli, respectively, and the log reduction value increased to 2.16 log and 2.65 log for films with 10% ZEO. However, the films lacked antimicrobial activity when tested in vapour phase. Finally, thin zein films loaded with 10% ZEO were successfully applied as a coating on PP bags. The effectiveness of the active bags was tested in a more complex medium than liquid bacterial growth media, that is cow's milk inoculated with the above microorganisms. This work offers a successful approach on the use of zein proteins for active food packaging.