Cold plasma treatment to prepare active polylactic acid/ethyl cellulose film using wheat germ peptides and chitosan

In this study, the surface of the polylactic acid/ethyl cellulose (PLA/EC) blend film was modified by dielectric barrier discharge (DBD) plasma treatment to facilitate the spin-coating of chitosan (CH) and wheat germ bioactive peptides (PEP) obtained from enzymatic hydrolysis of defatted wheat germ protein isolate on the surface of the film. The suitable plasma treatment condition was 5 min at 20 kV according to ATR-FTIR, AFM, SEM, water angle contact, and water solubility results. Increasing the surface roughness and oxygen-containing functional groups (CO and -OH) improved coating by PEP and CH. The PEP-coated film had better antioxidant activity than CH-PEP and CH-coated films. The results of antimicrobial activity demonstrated that PEP-coated film could reduce the growth of gram-negative bacteria (Escherichia coli) and gram-positive bacteria (Staphylococcus aureus). The PEP-coated film had competitive antibacterial properties with CH-coated. Hence, the obtained PEP-coated PLA/EC film could be a promising candidate for antioxidant and antibacterial food packaging.