Polycaprolactone sub-micrometric fibers optimization for primary packaging loaded with fatty acids as natural phase change materials

Currently, active food packaging is one of the most important means of preserving food quality and reducing losses. Refrigerated and frozen foods are among the most wasted products. However, efforts aimed at temperature control systems are very sparse and limited to refrigerated containers. Therefore, in this work, polycaprolactone fibers optimization through electrospinning is proposed for the production of innovative materials for primary packaging intended for foods subjected to the cold chain. The novelty lies in the substances loaded into the fibers, linoleic and oleic acid, two natural phase change materials. In fact, no work has ever investigated the direct loading of fatty acids inside polycaprolactone fibers. The best set of parameters to obtain submicrometric fibers was identified in polycaprolactone at 20% respect to the volume of the solvent composed by acetone and acetic acid 3:7 v/v, processed at 19 kV and 1.7 mL/h. The influence of fatty acids, loaded from 10 to 30% w/w, was evaluated by mechanical tests that highlighted a reduction in polycaprolactone fibers stiffness with tensile strength in accordance with conventional standards. The thermal properties analysis revealed the establishment of chemical interactions between the polyester and the fatty acids with consequent loss of thermoregulation properties. Finally, the migration test conducted in food simulant confirmed the obtainment of non-migratory materials, with release of less than 2% after 14 days. These results, although preliminary, help fill the gap in the architectures of these interesting materials which showed to have the potential to be applied as thermal insulating packaging layer.