Natural deep eutectic solvent-assisted incorporation of anthocyanins into cellulose acetate nanofibers for halochromic sensors

Intelligent food packaging can help reduce food waste by providing consumers real-time information about product freshness. They can be produced using natural pigments with pH-dependent color changes, which makes them promising candidates for colorimetric sensors. This study reports the development, through solution blow spinning (SBS), of cellulose acetate (CA)-based nanofibers loaded with anthocyanins solubilized in natural deep eutectic solvents (NADES). CA nanofibers were obtained by SBS using CA/PEO (polyethylene oxide) co-solutions, followed by PEO removal. Anthocyanins from grape pomace (GP), sweet potato (SP), and black carrot (BC) were incorporated into pectin solutions solubilized in a choline chloride–glycerol NADES (CC-GLY). The halochromic sensors were characterized regarding their morphological, thermal, and water-related properties. Anthocyanins incorporation decreased CA onset degradation temperatures and increased its melting enthalpy, suggesting improved chain packing. The fibers containing anthocyanins were more hydrophilic and more soluble. Exposure to ammonia vapor produced visible colorimetric responses, with CA/BC achieving the highest ΔE values (24.60 ± 0.50) and a detection limit as low as 1.73 × 10 −6 mol L −1 . Finally, a proof-of-concept assay confirmed CA/BC applicability for monitoring salmon spoilage via headspace exposure (ΔE = 26.52 ± 0.97) after 144 h at 4 °C and ΔE = 28.49 ± 1.04 after 48 h at 25 °C). The results demonstrate that CA nanofibers doped with anthocyanins are promising natural materials for intelligent packaging applications, enabling prompt and sensitive detection of food spoilage. • Anthocyanin-loaded CA nanofibers were developed via solution blow spinning. • NADES enabled efficient anthocyanin incorporation into CA-based nanofibers. • Sensors exhibited rapid, visible color changes under alkaline spoilage conditions. • Nanofibers with anthocyanins from black carrots showed the highest ammonia sensitivity. • The system offers a promising strategy for intelligent salmon freshness monitoring.