TANNIC ACID-CROSSLINKED CASEIN FILMS WITH IMPROVED MATERIAL PROPERTIES

M.L. PICCHIO; R.J. MINARI; ALVAREZ IGARZABAL, CECILIA INES

Los Cocos

Simposio; XII Simposio Argentino de Polimeros 2017; 2017

UNC-CONICET

Over the past few years, the interest for edible packaging materials as a replacement of traditional nonbiodegradable plastic films has grown, mainly driven by the increasing demand for environmentally-friendly,biodegradable and sustainable packaging products [1]. Among the different natural sources, milk proteinsare the most desirable hydrocolloids for producing edible films due to their high nutritional value, watersolubility, and emulsification capability [2]. For instance, casein films offer a good barrier to oxygen andother nonpolar molecules, because casein provides a large amount of polar functional groups (COOH-, NH2-and OH-) to the film matrix [3]. However, moisture sensitive and poor mechanical properties are the maindrawback of casein films. Therefore, chemical treatments must be applied to modify the polymer networktrough crosslinking of the polymer chains to improve protein film functionality. Some chemical agents used ascrosslinkers include aldehydes, calcium salts, 3-aminopropyl triethoxysilane, among others [4]. Enzymes suchas transglutaminase [5] and a natural crosslinking agent genipin [6] have been investigated as crosslinkingagents for casein films, but the high cost these crosslinkers limits their further application. In this workplasticized casein films were crosslinked in aqueous media using a simple vegetable-derived phenoliccompound, tannic acid. FTIR analysis and rheological measurements confirmed the crosslinking reactionbetween casein amine groups and tannic acid. The influence of concentrations of the crosslinking agent on themechanical properties, thermal stability, swelling kinetic, water vapor permeability, viscoelastic properties,and cytotoxicity were investigated in details. Moreover, SEM was applied to characterize both the surface andinternal morphology of the crosslinked materials. The results showed that tannic acid was an effectivecrosslinking agent for casein protein and that treated films presented improved physicochemical properties.