Gelatin-Based Active Edible Film with pH-Sensing for Maintaining and Monitoring Fish Freshness

The development of packaging films with food preservation and monitoring functions is of great significance and applications. Herein, gelatin was combined with rosmarinic acid (RosA) and blueberry anthocyanin extract (BAE) to fabricate RosA-gelatin/BAE (RGA) films with pH-responsiveness and long-term antioxidant and antibacterial activities. The films have better surface hydrophobicity and antiswelling performance than that of pure gelatin film. The films show good ductility and the elongation at break of the films can be easily adjusted in the range of 1.01–292.19% by adjusting the content of BAE. The films can block ultraviolet light, scavenge the ABTS+ radical, and kill bacteria almost 100%. Significantly, the films showed good pH/NH3 responsiveness as an obvious color change. Comparing with polyethylene film, there was a reduction of around 60.8% in the release of volatile base nitrogen compounds from crucian in storage using RGA5. Overall, these films may be useful for food preservation and real-time quality monitoring.