Development of antifungal films from nanocomplexes based on egg white protein nanogels and phenolic compounds

This work is aimed to develop antifungal films from nanocomplexes based on egg white protein nanogels (EWPn) and phenolic compounds (PC), carvacrol (CAR) and thymol (THY). EWPn-PC nanocomplexes were characterized by intrinsic fluorescence spectroscopy, particle size (DLS), ζ potential, encapsulation efficiency (EE), and antifungal properties. Nanocomplexes with proper encapsulation efficiency (> 80%) and antifungal activity against A. niger were obtained. Films were obtained by a casting process (40°C, 48 h) using glycerol as a plasticizing agent. EWPn-PC films were transparent and slightly yellow. SEM images revealed a porous, compact, and homogeneous microstructure. Tensile tests indicated less flexibility, breakability, and rigidity regarding the EWPn control film. Thermal analysis (DSC and TGA) highlighted an amorphous nature and resistance to high temperatures (~ 150°C). Moreover, they were permeable to water vapor and able to adsorb variable water amounts. Finally, their antifungal properties were verified using a sample of preservative-free bread. EWPn-PC films were able to prevent the fungal spoilage for 30 days of storage at 25°C. Sensory analysis for bread stored with EWPn-PC films indicated acceptability above the indifference threshold (> 5).