Properties of eco‑friendly orange peel-alginate-glycerol bioplastic films as potential food packaging applications

Abstract

The development of biofilms is an interesting strategy to reduce the use of conventional packaging materials to preserve and prolong the shelf life of foods. In this study, different concentrations of sodium alginate (SA) (0, 0.5, 1.0, 1.5 and 2.0% w/v) and glycerol (GL) (6.0, 4.0, 2.0, 1.0 and 0% w/v) on the properties of enriched films with orange peel (OP) powder were investigated. Physical, structural, thermal, mechanical, and barrier properties were characterized. The results revealed that incorporation of glycerol to OP-SA film-making solution trend to flexible and opaque films, while unplasticized sample did not form flexible films and were glossy. Moreover, decreasing glycerol and simultaneously increase alginate content led to decrease film thickness, moisture content, water solubility and oxygen transmission rate, whereas water absorption was increased. It was observed in micrographs that films with 1.5% SA and 1.0% GL had better surface attributes, and a further increase in GL and decrease in SA concentration was not found to be as favorable. Furthermore, FTIR spectra exhibited that intermolecular hydrogen bonding occurred between GL and OP-SA. X-ray diffraction showed that the films crystal structure has been changed significantly when the OP-SA and GL were mixed in. The plasticized films showed higher thermal stability as confirmed by TGA and DSC thermogram. The tensile strength of OP-SA-GL films was enhanced from 0.92 to 7.39 MPa, while elongation at break was decreased significantly from 20.76 to 2.67%. Consequently, orange peel-alginate-glycerol films could potentially be implemented in the food packaging.