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Effects of beta-glucan on casted thermoplastic starch films
A. BLENNOW (1), N. Ogrodowicz (2), K. Kruczala (2), M. Mikkelsen (3), J. Kirkensgaard (3), J. Maigret (4), D. Lourdin (4), K. Mortensen (3) (1) University of Copenhagen, Frederiksberg C, Denmark; (2) Jagiellonian University, , Poland; (3) University of Copenhagen, , Denmark; (4) Institut National De La Recherche Agronomique, , France.

Grain polysaccharides provide a major raw material for coming generations of advanced and environmental friendly materials. Thermoplastic starch (TPS) is processed using conventional plastic processing technology, such as casting, extrusion and molding (2). The adaptation for the daily use of TPS is achieved by chemical-modification or blending of starch with other polymers. For example mechanical performance of maize starch materials are improved by blending with polycaprolactone (Novamont, Mater-Bi; (1)). Alternatively, all-natural and fully compostable bioplastics can be generated by blending with other polysaccharides. maize starch (MSt) TPS prototypes were produced by casting with glycerol and different ratios of oat beta-glucan (BG) (100/0, 75/25, 50/50, 25/75 and 0/100 BG). Electron Paramagnetic Resonance tests using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) as a spin probe showed that EPR spectra of spin probe in the films containing BG but without glycerol had higher ratio between fast and slow rotation indicating looser chemical environment in BG containing films as compared to starch (3). This result was confirmed by high water vapor permeability at high BG concentration in the films. All films with BG but without glycerol showed a decreased brittleness and improved of cohesiveness as compared to 100% starch. The mechanical properties of blended films revealed an improvement of both stress and strain at break with increasing of BG content. Our data demonstrate that blending of starch with other natural polysaccharides is a leading path to improve functionality using all-natural polysaccharide systems.