Fe2+-loaded red radish anthocyanin (RRA) and zein composite nanoparticles (FZNPs) were firstly prepared to enhance the color and stability of RRA. The addition of Fe2+ caused anthocyanin to form color chelates, enhancing its pH color sensitivity. The prepared FZNPs showed good stability and anthocyanin retention during long-term storage. The obtained FZNPs are further loaded onto chitosan/zein (C/Z) film, resulting in a highly sensitive smart film capable of detecting changes in pH. When these FZNPs were incorporated into C/Z films, the mechanical properties of the films were improved (12.1 to 16.1 MPa) and the swelling degree of the films was reduced (422 % to 67 %). The addition of FZNPs also enhanced the hydrophobicity and thermal stability of smart films. The smart film showed visible color changes in response to pH variations and acetic acid gas. As the mushroom deteriorated, the color change of smart films provided a clear indicator of quality loss. Smartphone-based color identification and a WeChat mini program were further successfully utilized for rapid freshness analysis. This system provided a rapid, reliable method for evaluating food quality, with potential applications in food monitoring and supply chain management.
Keywords: Nanoparticles; Red radish anthocyanins; pH- responsive smart film.
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