Trehalose-Containing Hydrocolloid Edible Films Prepared in the Presence of Transglutaminase

In this article, edible hydrocolloid films were prepared by using Citrus pectins and the protein phaseolin in the presence of microbial transglutaminase, an enzyme able to catalyze isopeptide bonds between endo-protein-reactive glutamine and lysine residues. For the first time, trehalose, a nonreducing homodisaccharide into which two glucose units are linked together by a alpha-1,1-glycosidic linkage, was used as a component of hydrocolloid films constituted of both proteins and carbohydrates. Our data have demonstrated that these films act as very effective barriers to gases, especially to CO2. They also present a high antioxidant capability as measured by the 2,2-diphenyl-1-picrylhydrazyl scavenging assay. In addition, the films were characterized using Atomic Force Microscopy, a powerful tool used to evaluate film surface topography and roughness. The results of our experiments clearly indicate that the trehalose-containing films prepared both in the presence and absence of transglutaminase are composed of nanoparticles with a smooth surface, having similar roughness values (Ra). In conclusion, according to barrier and antioxidant properties and to their structure, it is possible to consider the trehalose-containing films as innovative bioplastics potentially able to protect different kinds of foods. (C) 2014 Wiley Periodicals, Inc.