title: Properties of starch-hydroxypropyl methylcellulose based films obtained by compression molding.
abstract: Corn starch-glycerol (1:0.3) films, containing or not citric acid (1g/100g starch) and HPMC (10 and 20g/100g 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.
authors.affiliation: Instituto de Ingeniería de Alimentos para el Desarrollo, Departamento de Tecnología de Alimentos, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Ortega-Toro
authors.affiliation: Instituto de Ingeniería de Alimentos para el Desarrollo, Departamento de Tecnología de Alimentos, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Jiménez
authors.affiliation: Instituto de Ingeniería de Alimentos para el Desarrollo, Departamento de Tecnología de Alimentos, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain. Electronic address: pautalens@tal.upv.es.
authors.forename: Pau
authors.initials: P
authors.lastname: Talens
authors.affiliation: Instituto de Ingeniería de Alimentos para el Desarrollo, Departamento de Tecnología de Alimentos, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
authors.forename: Amparo
authors.initials: A
authors.lastname: Chiralt
keywords: Citric acid; Compression molding; Crystallization; HPMC; Starch