Synergistic PVA/zein electrospun nanofiber array with curcumin-alizarin: a water-resistant, sensitive colorimetric platform for graded pork freshness monitoring

In this work, a synergistic polyvinyl alcohol (PVA)/zein electrospun nanofiber array was fabricated using curcumin and alizarin as dual responsive pigments for visual pork freshness monitoring. The water solubility of the PVA/zein composite reduced from 100.00% to 31.74%–35.42% ( P < 0.05), exhibiting remarkably enhanced water resistance. The dual-pigment array displayed continuous color transitions from pH 4.0 to 11.0 and detected ammonia and dimethylamine at 1 ppm, whereas alizarin-only films needed 5 ppm. The total color difference ( ΔE ) of the array showed strong linear correlations with thiobarbituric acid reactive substances (TBARS, r = 0.98), pH ( r = 0.95), and total volatile basic nitrogen (TVB-N, r = 0.98) in pork during refrigerated storage. Notably, the array enabled visual grading of pork freshness (fresh/sub-fresh/spoiled) and exhibited excellent color stability under ambient and refrigerated conditions. This study presents an eco-friendly and scalable intelligent packaging platform with great potential for real-time, on-site food freshness assessment.