A pH-sensitive film based on chitosan/gelatin and anthocyanin from Zingiber striolatum Diels for monitoring fish freshness

• Published in: Food Chemistry: X Vol. 23; p. 101639
• Main Authors: Qin, Yuyue, Wang, Yurou, Tang, Zhenya, Chen, Kejun, Wang, Zhengxuan, Cheng, Guiguang, Chi, Hai, Soteyome, Thanapop
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 30.10.2024; Elsevier
• Subjects: Anthocyanin; Fish freshness; pH-sensitive film; Visible color change; Zingiber striolatum Diels; Anthocyanin; Zingiber striolatum Diels; pH-sensitive film; Fish freshness; Visible color change
• ISSN: 2590-1575; 2590-1575
• DOI: 10.1016/j.fochx.2024.101639

As a new type of packaging method, the anthocyanin-based pH-sensitive indicator film has gained much attention owing to low cost, small size, and visually informative property. In this study, an intelligent film based on chitosan/gelatin (CG) matrix with Zingiber striolatum Diels (ZSD) anthocyanin for fish freshness monitoring was developed. The film properties, including thickness, moisture content, color, mechanical properties, UV–vis light barrier property, as well as pH and ammonia sensitivity, were evaluated. The CG-ZSD films exhibited a more compact structure when compared with the CG film. The CG-ZSD20 film showed the highest elongation at break (6.33 ± 0.62%) and lowest tensile strength (20.0 ± 0.58 MPa). FTIR spectra revealed the strong hydrogen bond interactions between ZSD and polymer matrix. Film incorporated with 15% anthocyanin extract has increased melting temperature at 118.9 °C, and a lower weight loss (13.8%) at melting temperature. In pH 1–14 buffer, the color of CG-ZSD films underwent a significant change from red to yellow-green. The CG-ZSD15 film was utilized for monitoring fish freshness and showed visible color changes from deep purple to brown. The total volatile basic nitrogen content and pH value changes of fish were closely related to the visual color changes in film. This demonstrated that the film was a highly pH-sensitive film for quantifying fish freshness in real-time. •The indicator film was prepared by blending chitosan with gelatin.•The pH-sensitive film was based on anthocyanin from Zingiber striolatum Diels.•Effect of Zingiber striolatum Diels on the physicochemical property was determined.•The infrared spectra confirmed the structural change in matrix and anthocyanins.•The film was applied to indicate fish freshness with evident color change.