Thermoplastic starch and bioactive chitosan sub-microparticle biocomposites: Antifungal and chemico-physical properties of the films

In this study, chitosan (C) tripolyphosphate (T) sub-micro particles containing ungeremine (CTUn), an alkaloid particularly active against Penicilliumroqueforti, a fungus responsible of the bakery products deterioration, were prepared through external gelation crosslinking process. The particles were included in a thermoplastic starch based polymer Mater-Bi (MBi), and MBi/CTUn bioactive biocomposites were obtained. The films showed bioactivity against P. roqueforti. In particular, the bioassays were performed on films with different concentration of CTUn and at different pH values. CTUn particles influenced MBi crystallization (DSC analysis) and promoted thermal degradation of MBi starch component (TGA). Morphological analysis confirmed even distribution of sub-micro particles into the polymeric matrix. Water permeability slightly increased, as expected, whereas oxygen permeability decreased. Tensile tests showed CTUN sub-microparticles improved rigidity and tensile strength of the films at the expense of ductility. Finally, MBi/CTUn biocomposites evidenced interesting performances potentially exploitablein bioactive bakery based food packaging materials.