Effect of sorbitol at different concentrations on the functional properties of gelatin/carboxymethyl cellulose (CMC)/chitosan composite films

Abstract

This study investigated consequent functional effects (mechanical and physical) on Gelatin/ CMC/Chitosan composite films from the addition of sorbitol. With glycerol as a plasticizer, solutions for Gelatin/CMC/Chitosan composite films containing graduated sorbitol concentrations (0%, 5%, 10%, 15%, 20%, 25% and 30%), were cast on a petri dish and oven dried at 45˚C. The fabricated films were then characterized for tensile strength, elongation at break (EAB) and puncture resistance (mechanical properties); as well as film thickness, water vapor permeability (WVP), thermal properties, light transmittance and transparency (UV and visible light transmission), biodegradability, and X-ray diffraction (physical properties). Results indicated that by increasing sorbitol concentration, melting point and tensile strength decreased overall (p<0.05). However, films with 25% sorbitol content increased tensile strength due to antiplasticization. EAB increases with sorbitol concentration for 5% and 10% however shows no trends for addition of 15%-20% due to phase segregation as plasticizer exceeds compatibility limit of film. Water vapor permeability, light transmittance, transparency and amorphous consistency all increased as sorbitol concentrations increased (p<0.05). Sorbitol also decreased glass transition (Tg) (range: 42.6–43.2°C). Using the soil burial method, there were no significant difference (p>0.05) in weight loss (%) as sorbitol concentrations increased. The addition of 10% sorbitol to the Gelatin/CMC/Chitosan composite films under study demonstrated satisfactory mechanical properties and low water vapor penetration. Film C (10% sorbitol) demonstrated sufficient mechanical properties with 1.51 MPa for tensile strength, 5.05% for EAB, 6.36N for puncture force in terms of flexibility and low WVP at 3.83 g.mm/h2.Pa compared to all other formulations. CE/g DW) and capacities (2.00 ± 0.01 µmol TEAC/g DW and 0.84 ± 0.01 µmol TEAC/g DW) amongst four species of seaweed.