Temperature-Responsive Antimicrobial Nanofibrous Film Encapsulating Cinnamon Oil for Chinese Bayberry Preservation

Abstract

This research developed an active food packaging system featuring a tailored controlled-release mechanism. The system was fabricated using temperature-responsive poly(N-vinylcaprolactam) (PNVCL) nanofibers with a core-shell architecture. The resulting film incorporated cinnamon essential oil (CEO) as a natural preservative within a composite structure consisting of PNVCL, polyvinyl alcohol (PVA), polylactic acid (PLA) and CEO. The nanofiber film obtained via coaxial electrospinning exhibited a sandwich-like structure; the obtained fiber membrane is abbreviated as PP/PC, and the number represents the essential oil content. The PP/PC-4 composite demonstrated exceptional physical barrier properties and mechanical strength, with a WVP as high as 5.74 ± 0.37 (g·mm)/(m2·h·kPa). It also achieved the highest maximum force, elastic modulus, and tensile strength, recorded at 3.08 ± 0.31 N, 228.86 ± 15.46 MPa, and 5.26 ± 0.72 MPa, respectively, along with superior thermal stability. FTIR spectroscopy confirmed molecular interactions, specifically through C–H bonding, between the PLA/CEO core and the PNVCL shell layers. After 5 d of storage at 40 °C, the PP/PC-4 film retained substantial antibacterial efficacy. The antifungal efficacy demonstrated the highest performance, exceeding the control group by 32%. The weight loss rate on day four was 28%, significantly lower than other groups, while the hardness retention rate was 73% higher than the control group and 44% higher than PLA/CEO (4%). Application of this material prolonged the shelf life of Chinese bayberry (Myrica rubra) by 4 d while enhancing key preservation metrics. Owing to its advanced barrier properties, mechanical performance and temperature-modulated release characteristics, this PNVCL-based nanofiber film demonstrated strong potential as an intelligent packaging material for prolonging the freshness of perishable food products.