Multifunctional intelligent film integrated with purple sweet potato anthocyanin and quercetin-loaded chitosan nanoparticles for monitoring and maintaining freshness of shrimp

Herein, an antioxidant, antibacterial and pH-sensitive multifunctional film is fabricated by incorporating anthocyanins-rich purple sweet potato extract and quercetin-loaded chitosan nanoparticles in agar /sodium alginate polymer matrix for monitoring and maintaining the freshness of shrimp. The film shows distinguishable color changes as pH changes and is highly sensitive to volatile ammonia. Moreover, the digital color information of the film is obtained by smartphone combined with RGB (red/green/blue) analysis. The G/R values are successfully used for the evaluation of shrimp freshness. More importantly, the film exhibits strong UV-blocking, antioxidant, antibacterial properties, and excellent mechanical, water vapor barrier properties, which enables the film to be used as a food packaging film. Notably, shrimp packed with the film can extend shelf life to about 36 h in refrigerated storage. Consequently, the multifunctional film can be applied to intelligent packaging for not only real-time indicating but also high-efficiently preserving the freshness of animal-derived foods.