Development and comparison of different polysaccharide/PVA-based active/intelligent packaging films containing red pitaya betacyanins

Betacyanin-rich red pitaya flesh extract (RPFE) was blended with different polysaccharides (chitosan, κ-carrageenan and locust bean gum) and polyvinyl alcohol (PVA) based matrices to prepare active/intelligent packaging films. The structural, physical and functional properties of different polysaccharide/PVA-RPFE films were compared for the first time. Results showed chitosan/PVA-RPFE film, κ-carrageenan/PVA-RPFE and locust bean gum/PVA-RPFE film had homogeneous, layered and nodular cross-sections, respectively. Betacaynins in RPFE established strong hydrogen bonds and electrostatic interactions with chitosan. However, betacaynins mainly established hydrogen bonds with κ-carrageenan and locust bean gum. Chitosan/PVA-RPFE film was reddish brown whereas κ-carrageenan/PVA-RPFE and locust bean gum/PVA-RPFE films were reddish purple. Polysaccharide/PVA-RPFE films had different light transmittance, moisture contents (20.22–27.54%), water vapor permeability (8.36–10.25 × 10−11 g m−1 s−1 Pa−1), tensile strength (13.89–41.07 MPa), elongation at break (10.27–72.08%), pH-sensitivity and ammonia-sensitivity. When the films were stored at 4 °C and 20 °C for 21 days, locust bean gum/PVA-RPFE film exhibited the highest color stability and antioxidant stability. Meanwhile, locust bean gum/PVA-RPFE film effectively indicated the freshness of shrimp when shrimp was stored at 4 °C and 20 °C. The results suggested the structural, physical and functional properties of betacyanin-rich and polysaccharide-based films were greatly affected by the type of polysaccharides.