Development of gelatine-based edible film by addition of whey powders with different demineralisation ratios: Physicochemical, thermal, mechanical and microstructural characteristics

The effects of using whey powders with different demineralisation rates on the physicochemical, thermal, mechanical, and microstructural properties of gelatine-based edible films were investigated. Films were produced from film-forming solutions (FFS) containing whey powder (WP) and 50, 70 and 90% demineralised whey powder (50DWP, 70DWP, 90DWP). The addition of whey powders increased the pH and particle size values of FFS. The zeta potential decreased significantly in the WP sample and gradually reduced depending on the demineralisation rate in the DWP samples. The addition of whey powders partially increased the density of the films. WP addition reduced the hydrophobicity of the film, while the addition of DWPs did not cause any change. The addition of whey powders decreased the L* and a* values of the films while increasing the b* values. Control was the most transparent, while 70DWP and 90DWP films had higher opacity. WP films had the most uniform and smooth surface. The highest degradation temperature (269.64 °C) was observed in the control sample. The weight loss of the control was 95%, whereas those of WP and DWP samples were 88–89%. WP addition reduced the tensile strength and increased the elasticity of the films.