Production and properties of smart packaging film based on gelatin-chitosan containing Echium amoenum anthocyanins and reinforced with crosslinkers for fish packaging.

Gelatin (G)- chitosan (Cs) composite packaging films were produced with incorporation of citric acid (CA) and/or cinnamaldehyde (C) as chemical crosslinkers. Then, the extract containing Echium amoenum (EA) anthocyanins (10 % v/v) as a pH indicator was added to G/Cs-based films containing the crosslinker. Physicochemical, composability and microbial properties of the obtained films were evaluated. The results showed that the films had a uniform, transparent appearance, and were capable of blocking UV rays. The G/Cs/CA5%/EA film showed better physical properties, higher mechanical strength (increase of 7.3 %), WVP (decrease of 1.98 %), lower stretchability (25.11 %), and higher thermal properties compared to the G/Cs /C5%/EA film. Simultaneous incorporation of EA and 5 % CA into the film led to a decline in WVP, water solubility (7.4 % reduction), and moisture content (1.23 % reduction) of the films, while the antioxidant properties (26.71 %) of G/Cs/C5%/EA were higher compared to G/Cs/CA5%/EA (14.31 %). SEM analysis revealed that films containing CA exhibited a smoother surface morphology. Finally, the films demonstrated obvious color changes due to fish spoilage and exposure to ammonium vapor. On the other hand, according to the results, the G/Cs/CA5%/EA film has better physical and chemical properties than other films.