Dynamic pH-Responsive Labeling System Based on Polyvinyl Alcohol/Arabinoxylan Nanofibers Incorporating Purple Cabbage Anthocyanins for Real-Time Food Freshness Monitoring

The fabrication of a real-time intelligent indication label for food freshness has emerged as an effective strategy to reduce food waste and improve food safety. In this study, utilizing polyvinyl alcohol (PVA) and arabinoxylan (AX) as the polymer matrices, and incorporating purple cabbage anthocyanins (PCAs) as natural pH-responsive agents, we fabricated a PVA/AX/PCA nanofiber-based intelligent indication label via electrospinning. The results confirmed that the nanofibers exhibited uniform morphology and good structural stability, with the PCA successfully embedded within the nanofibers. The nanofiber membrane exhibits a low water contact angle (54°) and demonstrates a tensile strength of 5.34 ± 0.09 MPa with an elongation at break of 32.43 ± 1.02%, while maintaining a certain degree of flexibility. The nanofiber labels exhibited distinct color changes within a wide pH range (2 to 12), which confirms their pH-responsive characteristics. After being stored at 4 °C and 25 °C for 14 days, the maximum color difference related to storage stability was 1.53 ± 0.02. In practical applications at 25 °C, this intelligent label demonstrated significant color changes when monitoring low-temperature-cooked sausages and fresh shrimp, with total color differences of 41.57 and 53.06, respectively. Degradation experiments showed that the nanofiber labels gradually decomposed, reflecting good biodegradability and environmental-protection characteristics. In conclusion, the green intelligent indication label developed in this study offers a feasible solution for real-time monitoring of food quality.