Effect of Cellulose Nanocrystals from Sugarcane Bagasse on Whey Protein Isolate-based Films

Whey protein isolate (WPI) has been utilized as edible film or food packaging material. However, WPI films are hydrophilic due to highly polar amino acids which provide a moderate barrier to water vapor and low mechanical properties. To overcome these drawbacks, cellulose nanocrystals (CNCs) extracted from sugarcane bagasse were incorporated with whey protein. FTIR and TGA were used to confirm the changes in chemical structures and to observe the thermal properties, respectively. The CNCs had sizes of 200-300 nm and diameters of 20-40 nm using TEM and AFM technique, respectively. Different amounts of CNCs (0-8 wt% based on WPI) were added into whey protein solution and formed films. The lightness and transparency of the films tended to decrease with increasing WPI content. The water activity (a) and water solubility of those films increased, whereas their water contact angle values decreased, implying that the film became more hydrophilic when the cellulose nanocrystal was added. The addition of CNCs increased the tensile strength and Young's modulus and reduced the water vapor permeability of WPI-based CNC films. However, the CNCs did not change the oxygen permeability of the film. Therefore, the obtained WPI films provided good mechanical performance and may be promising as an alternative product for film packaging.