Assessment of film-forming potential and properties of protein and polysaccharide-based biopolymer films

This study assessed the film-forming abilities of six types of proteins, as well as six types of polysaccharides at various concentrations (proteins: 0-16%; polysaccharides: 0-4%) and heating temperatures (60-80 °C). Biopolymer films evaluated included: sodium caseinate (SC), whey protein isolate (WPI), gelatine (G); caboxymethyl cellulose (CMC), sodium alginate (SA) and potato starch (PS). Screening trials showed that optimal film-forming conditions were achieved using SC and G (4% and 8%), WPI (8% and 12%), PS, CMC (2% and 3%) or SA (1% and 1.5%) solutions heated to 80 °C in combination with 50% (w/w) glycerol. Films manufactured from 1.5% SA, 8% G and 3% CMC had the highest tensile strength (24.88 MPa); flexibility (89.69%)/tear strength (0.30 N) and puncture resistance (22.66 N), respectively. SC, WPI and G-based films were more resistant to solvent than SA, CMC and PS. Film permeability to water vapour and oxygen decreased in the order: 12% WPI to 1% SA and 12% WPI to 1% SA. All films tested were impermeable to oil.