Structure–function relationship and multivariate quality correlation of Echium amoenum anthocyanin-loaded millet starch/PVA smart films for monitoring of camel meat freshness

Colorimetric indicators in intelligent food packaging enable real-time monitoring of food freshness through visible color changes. In this study, millet starch/polyvinyl alcohol films containing 4, 8, and 16% Echium amoenum anthocyanins were developed to monitor camel meat freshness. Increasing anthocyanin content enhanced film thickness, elongation at break, and antioxidant activity, while reducing tensile strength. The 8% formulation (MPE 8%) showed the best overall performance, with suitable mechanical properties, a uniform microstructure, appropriate crystallinity, moderate opacity, and the lowest water vapor permeability. This film exhibited clear and reversible color changes from red (pH 5) to green (pH 8), consistent with responses under real packaging conditions. During 8 days of refrigerated storage, meat pH, TVB-N, and total viable count increased and showed a strong negative correlation with film color difference (ΔE) (r ≈ 0.92–0.95). These results indicate that MPE 8% is a reliable and biodegradable indicator for visually assessing camel meat freshness.