Ethylene vinyl alcohol/calcium peroxide composite films for antibacterial packaging applications

Antibacterial packaging prevents the growth of microorganisms, thus extending the shelf life of food products. Calcium peroxide (CaO₂) releases H₂O₂ when in contact with H₂O and therefore exhibits promise as an alternative to liquid H₂O₂. Despite its strong antibacterial properties, studies regarding the use of CaO₂ in antibacterial packaging are limited. In this study, ethylene vinyl alcohol and calcium peroxide (EVOH/CaO₂) composite films with varied CaO₂ contents of 0.5–5 wt% were prepared via solution casting. Further, their mechanical, chemical, thermal, morphological, and barrier properties were extensively analyzed. The EVOH/CaO₂ composite films containing 3 and 5 wt% CaO₂ significantly inhibited the microbial growth of both Gram-negative and Gram-positive bacteria, which was attributed to the release of H₂O₂ from the films. Furthermore, cytotoxicity studies confirmed that the EVOH/CaO₂ composite films were noncytotoxic and safe for use. However, the EVOH/CaO₂ composite films failed to improve the barrier properties and thermal stability because of the weak interaction between EVOH and the CaO₂ nanoparticles and poor dispersion of CaO₂ into the EVOH matrix. These findings highlight the potential of the CaO₂ and EVOH/CaO₂ composite films as efficient antibacterial materials. Furthermore, they indicate the need to strengthen the chemical interaction between CaO₂ and EVOH so as to enhance the applicability of the films in food packaging and biomedicine.