Weed Out the Many Chemistries of Cutin Oligomeric Mixtures: Developing Antimicrobial Films by Blending with Carboxymethylcellulose.

Valorization of agro-industrial residues like tomato pomace is supported by the growth of a circular economy. Tomato pomace is a widely used source of the cutin polyester, a raw material for creating biobased materials and coatings. Cutin is usually incorporated into materials in the form of its hydrolyzable products. In this study, we focused on the production of biopolymer films composed of carboxymethylcellulose (CMC) and cutin oligomeric mixtures (COMs) yielded by chemical or supercritical water hydrolysis (SCWH). Either COM and their derived materials were comprehensively characterized (e.g., NMR, GC-MS, MALDI-TOF MS), including antimicrobial properties against E. coli and S. aureus, two foodborne pathogens. The results show that despite their compositional differences, both COMs reported similar behavior in direct antimicrobial activity: kill ≤92% of S. aureus cells but promote E. coli growth. The materials comprising COMs showed variable hydrophobicity and reduced water uptake compared to controls. The COMs improved the materials killing efficacy against S. aureus, regardless of the fact that only those yielded by SCWH (richer in monomers) showed a concentration-dependent effect. All tested materials failed to inhibit the adhesion of S. aureus, and while COMs addition did not improve the materials' capacity to kill E. coli, it effectively blocked its adhesion.