Characterization of vanillin cross-linked chitosan/whey protein isolate films: Effects of mandarin peel extract encapsulated by different methods

Abstract This study aimed to produce environmentally friendly films from chitosan (CH) and whey protein isolate (WPI) by cross-linking with vanillin and incorporating microcapsules of mandarin peel extract. Freeze-drying and spray-drying were used to encapsulate mandarin peel extract with maltodextrin and WPI. The encapsulation efficiencies were 63.72% for spray-drying and 55.26% for freeze-drying. The encapsulated powders had high amounts of bioactive components. FT-IR analysis confirmed the encapsulation, and SEM revealed differences in the microstructures of the powders. Results showed that crosslinking reduced parameters such as moisture content (from 21.56% to 13.77%), water solubility (from 42.63% to 29.68%), and water swelling (from 69.08% to 61.26%) in films produced with CH and WPI. However, the mechanical strength of films decreased. Moreover, mandarin essential oil (MEO) was added to the films containing spray-dried powder. Some improvements in the water barrier properties were observed in the MEO-added films. Cross-linked films containing MEO were rich in bioactive compounds and effective against pathogens, including Listeria monocytogenes , Bacillus cereus , Staphylococcus aureus , and Salmonella typhi . The results revealed that cross-linking and the enrichment of microencapsulated extracts significantly enhanced the film’s properties, making it a promising candidate for active food packaging applications.