A completely bio-based corn starch/sodium carboxymethyl cellulose film with antibacterial and antioxidant performance modified by a natural alcohol ester of amino acid and curcumin

Abstract

To address the ecological pollution caused by synthetic antimicrobial agents in conventional food packaging films, we have successfully developed a fully bio-based and sustainable food packaging film that exhibits exceptional antibacterial and antioxidant properties. In this study, we designed and synthesized two novel natural alcohol esters of amino acid (NAEAAs)—L-Trp-Men and L-Trp-Bor—through esterification reactions involving L-tryptophan (L-Trp) and L-Menthol or Borneol, respectively. A multifunctional composite film system was constructed using natural corn starch (CS) and sodium carboxymethyl cellulose (CMC) as the matrix materials, with NAEAAs serving as the antimicrobial active components and curcumin (Cur) as the antioxidant. Experimental results demonstrated that the CS/CMC/Men2/Cur2 composite film, containing 2 wt% additives, exhibited nearly complete (≈100 %) broad-spectrum antibacterial efficiency against both Escherichia coli and Staphylococcus aureus, alongside a DPPH radical scavenging rate of 45.69 ± 1.39 %. Cytotoxicity tests confirmed the excellent biocompatibility of NAEAAs, which hydrolyze into amino acids and natural alcohols, thereby minimizing environmental contamination. These fully natural material-based films present a novel approach for developing green, pollution-free, and renewable bio-based food packaging materials.