Plasticized cellulose bioplastics with beeswax for the fabrication of multifunctional, biodegradable active food packaging

Plasticized cellulose bioplastics with antioxidant and antimicrobial properties were prepared by blending cellulose and glycerol in a mixture of trifluoroacetic acid and trifluoroacetic anhydride, adding a solution of beeswax in chloroform, and subsequent drop-casting. Optical, chemical, structural, mechanical, thermal, and hydrodynamic properties were fully characterized. In addition, the biodegradability in seawater was investigated by determination of the biological oxygen demand. The incorporation of beeswax ruled out the transparency and UV blocking, modified the main mechanical parameters, and improved the thermal stability and the antioxidant capacity, as well as the hydrodynamic and barrier properties. In general, these features were comparable to those of common petroleum-based food packaging plastics. Such changes were explained by the incorporation of beeswax into the polymer matrix, as determined by infrared spectroscopy and X-ray diffraction. These cellulose-beeswax bioplastics were evaluated as viable food packaging materials by determination of the overall migration by using Tenax® as a dry food simulant, oxygen permeability at different relative humidities, measurement of antimicrobial activity against Escherichia coli and Bacillus cereus, and through preservation of fresh-cut pear slices, showing results similar to those obtained by using low-density polyethylene.

This work has been partially supported by the Spanish Research Council (CSIC) project 202040E003. S.G-P thanks the “Consejería de Transformaci´on Econ´omica, Industria, Conocimiento y Universidades” from Junta de Andalucía for her postdoctoral contract (POSTDOC_ 21_00008). The authors thank Cristina Amella for her assistance in preparing samples for the OTR tests and María del Rocío Mu˜noz-P´erez for her assistance in the preservation assay of pear slices.

Food packaging

Cellulose

Beeswax

Bioplastics

Barrier properties

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