Waste orange peels extracts for food packaging application

Recent research trends are focusing on the development of active food packaging by adding natural extracts with antioxidants and antimicrobial activity into packaging materials to increase the shelflife of the products. Natural extracts are sensitive molecules which can be denaturize under harsh conditions. To achieve their stabilization, natural extracts must be protected by encapsulation with different carrier materials. The objective of this work is the incorporation of orange peels extract into PLA film. The natural extract was obtained by processing the orange peels by drying, grinding, solvent extracting, concentrating and purifying. Then, different formulations of the purified extract, which showed antimicrobial activity against S. aureus, P. fluorescens and E. coli, were screened. In particular, freezedrying process was compared with two sprydrying processes, which implied pectin or cyclodextrin, as carriers. Each formulation was then included at increasing concentrations into PLA and the incorporation led to yellow films. Spraydrying encapsulation increased the thermal stability of the extract and did not change the degradation temperature of the PLA. Despite this, it reduced the mechanical properties and the permeability to water vapour of PLA. Based on these results, in the frame of the European project NEWPACK (HORIZON 2020 grant No.792261), different commercially available orange peel extracts (OPE) have been tested to be included in a PLAPHB film or as a coating or directly during the extrusion process. As first, the OPE have been characterized for bioactivity as antioxidant and antimicrobial agents against the most common pathogens growing on food products. The OPE which have showed the best bioactivity have been selected for the spraydrying encapsulation trials, starting from pectin and cyclodextrin, as carriers. Afterwards, the spraydried products have been checked again for their bioactivity and stability and the best resulting formulations will be used for the development of the active food packaging.