An intelligent active polylactic acid/gelatin nanofibrous membrane with Janus structure for meat freshness monitoring and preservation.

Real-time monitoring of food freshness and extending its shelf life are crucial for reducing food waste and enhancing food quality and safety. In this study, an intelligent active food packaging with Janus structure was fabricated by sequentially electrospinning a hydrophobic polylactic acid (PLA) nanofibrous membrane and a hydrophilic PLA/gelatin/cetyltrimethylammonium bromide (CTAB)/0.5 alizarin nanofibrous membrane. The incorporation of CTAB enhanced both the hydrophilicity and antibacterial activity. The water contact angle of the PLA@PLA/gelatin/CTAB/0.5 alizarin membrane decreased to 0° within 3 s, confirming the directional water transport capability. The membrane with 0.5% w/w alizarin achieved the highest antioxidant activity at 59.48%. The alizarin-loaded membranes exhibited significant colorimetric response under alkaline conditions, with ΔE above 5. In meat freshness monitoring applications, the bilayered membrane turned purple by Day 7, which was consistent with the change of pH. These results indicated the bilayered membrane has significant potential for application in intelligent active food packaging.