Overcoming the sensitivity-stability trade-off in colorimetric food sensors using immersion-electrospun natural anthocyanin-loaded PCL/PVP membrane.

Colorimetric pH indicators provide a visual means to monitor food freshness but often suffer from a sensitivity-stability trade-off. In this study, a bio-based sensor was developed by incorporating natural anthocyanins into immersion-electrospun PCL/PVP membranes. The optimized I41 membrane (PCL:PVP = 4:1) exhibited a helical-strip morphology with a high surface-area-to-volume ratio, enabling rapid analyte diffusion and strong color responsiveness. It showed a fast ammonia response (∼43 % within 1 min), excellent reversibility over ten acid-base cycles, and stable color retention over 14 days (ΔE < 2). During shrimp freshness monitoring, the sensor displayed a distinct color shift (ΔE = 41 at 30 h), consistent with biochemical spoilage indicators (TVB-N = 39.7 mg/100 g). These findings demonstrate that immersion electrospinning effectively mitigates the sensitivity loss typically observed in hydrophobic matrices, providing a practical pathway toward responsive, stable, and sustainable colorimetric sensors for intelligent food packaging.