Antimicrobial bilayer starch film containing zein electrospun fibers encapsulating thyme essential oil for cherry tomato packaging

Abstract Background This study evaluated the antimicrobial activity of thyme essential oil (TEO) encapsulated in electrospun zein fibers for use in bilayer films as active packaging for cherry tomatoes. The antimicrobial activity of TEO and bilayer films with 20%, 40%, and 60% TEO was assessed with agar diffusion and microatmosphere assays. Films containing 60% TEO were tested with viable cell count against microorganisms and applied as bioactive packaging for cherry tomatoes. Weight loss, decay rate, firmness, total soluble solids, titratable acidity, pH, and microbiological quality were analyzed over a 14 day storage period. Results The free TEO exhibited antimicrobial activity against all tested bacteria and fungi, with the strongest antibacterial activity against Listeria monocytogenes and Staphylococcus aureus and complete fungal inhibition in the microatmosphere assay. The 60% TEO bilayer films completely inhibited S. aureus and Penicillium crustosum . They reduced Escherichia coli growth by 71.5% and Aspergillus flavus growth by 71.3%. As active packaging for cherry tomatoes, after 14 days of storage, the bilayer films reduced weight loss from 14.7% to 6.8% and decay incidence from 83.3% to 33.3% compared with the control, while maintaining total soluble solids (5.0 °Brix), titratable acidity, and pH. The bilayer films also reduced E. coli by approximately 92% and decreased aerobic mesophilic bacteria by approximately 1.8 log colony‐forming units (CFU) g −1 and yeasts and molds by approximately 1.5 log CFU g −1 . Conclusion The results confirm TEO's antimicrobial effectiveness in bilayer films and potential for active packaging, offering a sustainable alternative to extend the shelf life of perishables and a promising technology for industrial fresh produce preservation. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.