Inclusion of antifungal plant metabolite in polysaccharide based matrix as bioactive food packaging material

Ungeremine is a betaine type alkaloid isolated from Pancratium maritimim L., 1 and thus could be synthesized by SeO2 oxidation of lycorine, which is the main Amaryllideacea alkaloid obtained in high yield from Sterbergia lutea Ker Gawl. a wild species coollected on the coasts Apulia region in South Italy. 2 Ungeremine have shown a very significant antifungal activity against Penicillium roqueforti,3 a filamentous fungus responsible of the bakery products deterioration. In this study, chitosan based microbeads containing ungeremine, were prepared by external gelation by using sodium tripolyphosphate (TPP) as crosslinking agent. The stability of the microbeads, as well as the loading efficiency of the antifungal metabolite were assessed at different pH and TPP concentrations and resulted particularly enhanced at low pH. All the microbeads evidenced antimicrobial activity against Penicillium roqueforti. The release kinetics of ungeremine was tailored by opportunely modulating pH and TPP concentrations. Morphological analysis evidenced the improvement of the structural cross linking density of microbeads including ungeremine and spectroscopic analysis emphasized the active participation of ungeremine to the crosslinking process occurring between chitosan and TPP. Finally, thermogravimetric analysis confirmed the increasing of free volume in threedimensional networks and their liability to thermal degradation.