Properties of starch hydroxypropyl methylcellulose based films obtained by compression molding

[EN] Corn starch glycerol (1:0.3) films, containing or not citric acid (1 g/100 g starch) and HPMC (10 and 20 g/100 g starch), are obtained by compression molding. The microstructure of the films, the thermal behavior, the X-ray diffraction spectra and the physical properties (mechanical, barrier and optical) were analyzed after 1 and 5 storage weeks at 25 °C and 53% relative humidity. The bonded citric acid and film solubility were also determined. Starch HPMC blend films showed a dispersed phase of HPMC in a continuous, starch-rich phase with lower glass transition than HPMC-free films. The addition of citric acid also provoked a decrease in glass transition in line with the partial hydrolysis of starch chains. Both components implied a decrease in the water vapour permeability while the oxygen permeability slightly increased. Although citric acid only provoked a small hardening effect in the films, it greatly decreased their extensibility (weak cross-linking effect), which seems to increase during film storage. Starch crystallization during storage was inhibited by both citric acid and HPMC.The authors acknowledge the financial support from the Spanish Ministerio de Educacion y Ciencia throughout the project AGL2010-20694. Rodrigo Ortega-Toro thanks the Conselleria de Educacio de la Comunitat Valenciana for the Santiago Grisolla grant.Ortega-Toro, R.; Jiménez Marco, A.; Talens Oliag, P.; Chiralt, A. (2014). Properties of starch hydroxypropyl methylcellulose based films obtained by compression molding. Carbohydrate Polymers. 109:155-165. doi:10.1016/j.carbpol.2014.03.059S15516510