Fabricating anti-ultraviolet and antibacterial films with lower water solubility from chitosan, glycerol and aloe emodin for pork preservation

Pure chitosan film is fragile and water-soluble, limiting its practical application in food packaging. In this study, adding glycerol and aloe emodin (AE) could simultaneously increase the flexibility of chitosan film. Meanwhile, glycerol also decreased its water solubility. When glycerol content was 40%, the elongation at break increased to 56.95% and the water solubility decreased to 37.01%. With AE addition increasing from 0% to 0.7%, the tensile strength reduced from 31.40 to 25.43 MPa, but elongation at break, water vapor permeability, and oxygen permeability rose from 60.50% to 74.35%, 1.01–1.62 g m−1 Pa−1 s−1*10−10, 0.06–4.81 cm3 mm−2 day−1 Pa−1*10−10, respectively. Besides, the total color change increased, and the light transmittance dropped, especially after adding 0.7% AE, it was near 0% in the ultraviolet region, exhibiting an excellent UV-blocking performance. The antibacterial ratio against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) could reach 94.99% and 96.56%, respectively. The pork packaged by the film containing 0.7% AE had lower malondialdehyde values (5.787 mg kg−1) and weight loss (54.15%) compared to the film without AE. Overall, this study figures out the mechanism of water insolubility of chitosan/glycerol film and provides a method for preparing chitosan-based film with UV-blocking and antibacterial properties.