Antimicrobial Edible Starch Films Obtained By Casting and Thermo‑compression Techniques

Abstract

Physicochemical and functional properties of edible starch-based active films containing or not natamycin and/or nisin as affected by the processing method (thermo-compression molding and casting) were analyzed in terms of barrier, thermal, mechanical and antimicrobial properties against Listeria innocua and Saccharomyces cerevisiae. The results revealed that the processing method significantly affected the properties of the films. Thus, the cast films were more transparent, resistant to rupture and stretchable and with higher glass transition temperature values, while the thermoformed ones showed a more homogeneous matrix with higher barrier capacity to oxygen and lower moisture content. On the other hand, the thermal stability was not affected by the type of processing of the films or by the antimicrobial incorporation, all the films exhibiting the typical range of polymer degradation temperature around 250–350 ºC. Moreover, the type of film processing method used, especially when using nisin as active compound, significantly affected the antimicrobial activity of the edible films. So, the maximum antimicrobial activity against S. cerevisiae and L. innocua was obtained when the films incorporating both antimicrobials were obtained by casting. Therefore, the functionality of these active edible films will be better preserved when applied by casting technique.