Preparation and characterization of active Cirish fructans-fish gelatin film: Physicochemical, antioxidant, and antimicrobial properties.

This study was aimed to evaluate the film-forming ability and characterization of ultrasonically extracted Cirish fructans (CF) and CF-cold-water fish gelatin (G) composite films. The film-forming solutions were prepared at different levels (CF100-0G, CF75-G25, CF50-G50, CF25-G75, and CF0-G100) and the corresponding data were analyzed based on one-way analysis of variance. The results indicated that CF addition led to an impressive increase in composite films thickness (69.38-86.45 μm), moisture content (16.05%-27.8%), surface hydrophobicity, tensile strength (5.73-17.89 MPa), elongation at break (0.83%-1.66%), Young's modulus (77.12-88.15 MPa), and Tg (38.83-47.4°C) which CF75-G25 had the highest values. Meanwhile, the solubility (77.12%-88.15%), WVP (1.89-2.86 × 10 -10 gm -1  s -1  Pa -1 ), and oxygen permeability (1.53-3.26 × 10 14  cm 3  m -1  s -1  Pa -1 ) of the composite films decreased. The FTIR spectra indicated the protein-polysaccharide interactions and revealed that the secondary structure of gelatin was shifted from triple-helix structure (1661 cm -1 ) toward α-helix structure (1650-1657 cm -1 ) when CF was incorporated. The microstructure observations indicated that unlike gelatin film, CF film exhibited the smooth and uniform surface without cracks and phase separation. It was found that CF films had high total phenolic content (6.73 mg GEA g -1 ) and showed DPPH radical scavenging activity (67.86%). On the other hand, it showed inherent antimicrobial activity against both gram-positive and gram-negative bacteria. The results indicated that CF and CF-cold fish gelatin have great potential as active films with improved physical, mechanical, and barrier properties.