Chitosan-Tripolyphosphate-Ungeremine sub-microparticles in Mater-Bi Polymeric Matrix: Novel Bioactive Food Packaging Biocomposites. Study of Antibacterial Properties, Releasing Kinetics and Chemico-Physical properties of the films

One of the greatest problems in food packaging system is prevention of food from the mold contamination. In particular, in the bakery products Penicillium roqueforti (PR) is the main contaminator associated to the food deterioration. Food packaging systems are responsible to protect food substrate from physical damage, chemical and biological contaminations. In addition, packages are designed to preserve the food quality and safety, extending their shelf-life. However, finalized to enhance the food packaging performances recently, the attention of research and industrial partnerships is increasingly focused on bioactive packaging. Antimicrobial food packaging is based on the incorporation of natural bioactive metabolites into polymer or biopolymer matrices, acts to reduce, inhibit or hinder the growth of microorganisms able to develop not only in the food but also in the packaging material itself. In particular, some plants material showed antifungal activity with potential application in food packaging. In this respect, ungeremine (Un) is one of the most active plant metabolites against P.roqueforti. Ungeremine is a betaine type alkaloids isolated from Pancratium maritimim L., a well knows species of Amaryllidaceae collected on Egypt northern coasts. Ungeremine was also obtained from SeO2 oxidation of lycorine, the main Amaryllideacea alkaloids. In this study, chitosan (Ch) based sub-micro particles containing ungeremine were prepared by using sodium tripolyphosphate (TPP) and formulated into Mater-Bi (MBi) polymer matrix. The Ch_TPP_Un/MBi composites were obtained by compression molding. The bioassay result of the films evidenced their activity against P.roqueforti. In addition, determination of residual ungeremine into films after 72h inhibition showed that, depending on the different food substrate pH, the diverse releasing pattern of fungicide from the package system could be expected. The morphological analysis confirmed a homogeneous distribution of sub-micro particles into MaterBi polymer matrix. The tensile test analysis showed that sub-micro particles could significantly decrease the ductility and slight increase in the elastic modulus of the films. Finally, thermogravimetric analysis confirmed specific physical interaction between chitosan based sub-microparticles and the starch fraction of MBi which, in turn, resulted in a decrease of thermal stability of MBi starch segments.