Efficient and sustainable production of intelligent nonwovens as indicators of food spoilage through solution blow spinning of proteins and natural pigments from agri-food waste

The efficient manufacturing of food spoilage indicators based on intelligent nonwovens represents a promising alternative to enable the application of these materials in food quality monitoring. The objective of this study was to rapidly produce intelligent nanofiber nonwovens made of zein/gelatin (Z/G) functionalized with various concentrations (5–15% w/w on the matrix) of anthocyanin-rich food-residue extracts from purple cabbage (CAE) or purple sweet potato (PAE) using the solution-blow-spinning (SBS) technique for use in food-quality-monitoring applications. The addition of CAE or PAE to the Z/G matrix reduced the viscosity of the solution and (consequently) the nanofiber diameters from 999 nm to 882 and 583 nm, respectively. Such incorporation also improved the mechanical, thermal, and water-related properties of the nanofibers and endowed them with antioxidant capacities. Nonwovens composed of Z/G nanofibers with added CAE or PAE, especially at concentrations of 15%, exhibited visible color changes (ΔE ≥ 3) that rapidly altered in response to pH (3–10) and when exposed to ammonia vapor. The nonwovens were successfully used to monitor the deterioration of pasteurized milk and fish fillets. They reveal a visual color change from pink at 0 h to a more intense pink at 48 h in response to milk deterioration and a color change from pink at 0 h to light brown after 48 h when the fish fillets were considered deteriorated. The use of these nanofiber nonwovens to monitor changes in food quality highlights the significant potential of the SBS technique and the use of anthocyanins from agri-food waste to produce new intelligent packaging materials for use in food applications.