Functional biopolymeric materials for active food packaging: the case of monolayer films of thermoplastic starch and olive leaf extract

abstract

Active packaging materials based on biopolymers and natural additives represent a significant innovation, offering a sustainable solution of packaging combined with multifunctional bioactive properties to extend the shelf-life of food products. In the present study, bioactive films composed of thermoplastic starch (TPS) and an olive leaf extract (OLE) were fabricated via solvent casting. OLE was used in different concentrations, namely 5 and 10 wt.%, and the films were plasticized with glycerol (20 wt.%). The ensuing homogeneous films are translucent (50% < transmittance <80%, opacity <2.3 mm(-1)) and exhibited a light-green coloration characteristic of OLE. The inclusion of OLE had a positive effect on the mechanical performance (Young's modulus approximate to 1.1 GPa), water resistance (water solubility <29% and moisture absorption <= 45%) and thermal stability (up to 200 degrees C) of the films. Furthermore, the incorporation of OLE in the plasticized TPS films originated materials with UV-blocking properties (transmittance <= 28%) and high antioxidant activity (DPPH scavenging activities of ca. 90%), as well as antibacterial action against a methicillin-resistant Staphylococcus aureus bacterial strain (maximum reduction of ca. 2.6-log [colony-forming units (CFU) mL(-1)] after 72 h). Lastly, when used to pack sliced pears stored at +4 degrees C for 7 days, the TPS/OLE-based films effectively delayed browning, mass loss and pH changes. Overall, the incorporation of OLE into plasticized TPS films demonstrates great potential for sustainable active food packaging, offering an approach to preserve the quality and extend the shelf-life of fresh food products.

keywords

RESISTANT STAPHYLOCOCCUS-AUREUS; CASSAVA STARCH; POLYPHENOLOXIDASE ACTIVITY; YERBA-MATE; ANTIOXIDANT; IMPREGNATION; CHITOSAN; LEAVES; AGENTS; COLOR

subject category

Biotechnology & Applied Microbiology; Engineering

authors

Sousa, R; Silva, JM; Verano-Naranjo, L; Cejudo-Bastante, C; Facchinatto, WM; Almeida, A; Silvestre, AJD; Freire, CSR; Vilela, C

Groups

G4 - Renewable Materials and Circular Economy

Projects

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

Engineering self-propelled cellulose-based Janus microrobots (Cell4Janus)

CICECO-Aveiro Institute of Materials R&D Unit Pluriannual Funding (CICECO-Aveiro Institute of Materials)

acknowledgements

The author(s) declare that financial support was received for the research and/or publication of this article. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UID/50011/2025 and LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020), financed by national funds through the FCT/MCTES (PIDDAC) and Centro de Estudos do Ambiente e Mar (CESAM) UID/50006 + LA/P/0094/2020 (DOI 10.54499/LA/P/0094/2020) through national funds. The project Cell4Janus (PTDC/BII-BIO/1901/2021, DOI: 10.54499/PTDC/BII-BIO/1901/2021), financially supported by national funds (OE) through FCT/MCTES, is acknowledged for the research contract of WF. FCT is also acknowledged for the research contract to CV (DOI 10.54499/2021.01571.CEECIND/CP1659/CT0024). This work is framed within the iM-PACK project, which is part of the PRIMA program supported by the European Union.