Development of antimicrobial food packaging films based on electrospun polycaprolactone nanofibers encapsulating thyme oil nanoemulsions

This study developed and characterized a novel antimicrobial food packaging film fabricated from electrospun polycaprolactone (PCL) nanofibers incorporated with thyme oil nanoemulsions (TONEs). The concentration of TONEs in the film ranged from 2.5 to 15 % (v/v). The physicochemical properties, including pH, viscosity, and water absorption of the film were evaluated, with results showing favorable values (TONEs pH ≈ 5.46, viscosity ≈ 0.26 cP, contact angle ≈ 109-127 0 and water absorption ≈ 21.47 %). The microstructure of the film was observed using scanning electron microscopy (SEM), which revealed the uniform dispersion of TONEs within the PCL nanofibrous matrix, with average fiber diameters ranging from 555.68 to 571.09 nm. The TONEs interaction within the PCL matrix in the film was evaluated by Fourier-transform infrared (FTIR) spectroscopy, which revealed hydrogen-bonding interactions between thyme oil components and PCL ester groups. The antimicrobial activity of the films was assessed against common foodborne pathogens, including Escherichia coli , Salmonella enterica , Staphylococcus aureus , and Bacillus cereus . The films containing 10 % and 15 % TONEs demonstrated significant inhibition zones on agar plates (up to 25 mm for Salmonella enterica ), confirming their excellent antimicrobial efficacy, with minimum inhibitory concentrations (MICs) as low as 0.078 % (v/v) for most pathogens. The nanoemulsion formulation exhibited optimal droplet sizes (75–99 nm) and polydispersity indices (<0.7), ensuring stable encapsulation and controlled release properties. These findings indicate that TONE-loaded PCL nanofibers are promising antimicrobial packaging materials capable of preventing the growth of foodborne pathogens. • Electrospun PCL nanofibers were functionalized with thyme oil nanoemulsions (TONEs) to create an advanced antimicrobial biomaterial. • The 10 % TONE achieved a small droplet size (81.24 nm) and high uniformity (PDI = 0.50), indicating excellent colloidal stability. • TONEs imparted potent, concentration-dependent antimicrobial activity against key Gram-positive and Gram-negative foodborne pathogens. • The films were highly effective against Salmonella enterica , exhibiting the largest inhibition zone (25 mm), despite the higher MIC. • The TONE/PCL nanofiber matrix is a sustainable, effective strategy for active food packaging to enhance safety and extend shelf life.