Zein-magnolol complexes assisted hydrogel film: Physical, antioxidant, antimicrobial properties and application on food packaging

Sodium carboxymethyl cellulose (CMC)-based films integrated with zein and magnolol complexes were prepared for food packaging with antimicrobial and antioxidant properties. The results showed that the secondary structure of zein changed upon complexation with magnolol. The scavenging ability of the complexes on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and 2, 2′-azinobis-(3-ethylbenzthiazoline-6- sulphonate) (ABTS) radicals was significantly higher than that of zein alone. The zein-magnolol complexes (ZMC) were then loaded into CMC to form a hydrogel film. The radical scavenging rates of DPPH and ABTS of CMC/0.5 ZMC (the proportion of ZMC in film solution at 0.5, v/v) were 32.24 % and 91.30 %, respectively, which were significantly higher than CMC film. The incorporation of the complexes also improved the mechanical properties, with a more than 3-fold increase in elongation at break (EB) value. In addition, the complexes-loaded hydrogel film also inhibited the growth of S. aureus, a common bacterium that can cause food poisoning. Cytotoxicity tests have revealed that the studied films are non-toxic, presenting good compatibility. The film also successfully maintained the nutrients in fresh-cut jackfruit by mitigating lipid peroxidation and the increase in malondialdehyde content during 8-day storage. Overall ZMC loaded CMC film provides a promising approach for food preservation against ultra-violet light, oxidation and microbial growth.