Open Access

ARTICLE

Melt Extrusion of Environmentally Friendly Poly(L-lactic acid)/Sodium Metabisulfite Films for Antimicrobial Packaging Applications

by Norma M. P. Machado¹, Gustavo C. Melo¹, Matheus F. Camargo¹, Giulianna G. Feijó¹, Bruna M. S. Putton², Clarice Steffens², Rogerio L. Cansian², Luiz A. Pessan¹, Francys K. V. Moreira^1,*

1 Department of Materials Engineering, Federal University of São Carlos, São Carlos, Brazil
2 Department of Food Engineering, Regional Integrated University of High Uruguay and Missions (URI), Erechim, Brazil

* Corresponding Author: Francys K. V. Moreira. Email:

(This article belongs to the Special Issue: 15th Brazilian Polymer Conference (15th CBPol))

Journal of Renewable Materials 2021, 9(2), 337-349. https://doi.org/10.32604/jrm.2021.011081

Received 13 July 2020; Accepted 04 September 2020; Issue published 15 December 2020

Abstract

Food packaging materials compounded with antimicrobial additives can substantially diminish the incidence of foodborne diseases. Here, poly(L-lactic acid) (PLA) films containing sodium metabisulfite (NaM) were produced by melt extrusion as an attempt to develop a new biodegradable material with antimicrobial properties for packaging. Life cycle assessment (LCA) simulations revealed that the environmental footprints of the PLA film did not change upon NaM addition, and that NaM is more eco-friendly than silver nanoparticles. The PLA/NaM films with NaM content varying from 0.5 to 5.0 wt.% were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and optical and mechanical properties determinations. The optical properties were sustained after the addition of NaM, but high NaM contents degraded the light transparence of the PLA matrix at some extent. The thermal stability and tensile properties of the PLA film decreased proportionally to the NaM content, while no changes were observed on T_g, T_m and X_c, as determined by DSC. Agar diffusion tests revealed that the PLA/NaM films had no antimicrobial activity on Saccharomyces cerevisiae at 35°C, which was related to the limited migration of NaM from the glassy PLA matrix. The biodegradable PLA films compounded with NaM through melt extrusion display adequate optical, thermal, and mechanical properties to cover most food packaging applications, representing an essential step toward the development of eco-friendly packaging materials that can potentially exhibit an antimicrobially active surface.

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