INIQUI   05448
INSTITUTO DE INVESTIGACIONES PARA LA INDUSTRIA QUIMICA
Unidad Ejecutora - UE
artículos
Título:
Mechanical Properties of High Amylose Starch Based Films Gelatinized at Low Temperature
Autor/es:
BERTUZZI, MARÍA ALEJANDRA; ARMADA, MARGARITA; GOTTIFREDI, JUAN C.
Revista:
Brazilian Journal of Food Technology
Editorial:
Instituto de Tecnologia de Alimentos ? ITAL
Referencias:
Lugar: Campinas; Año: 2012 vol. 15 p. 219 - 227
ISSN:
1981-6723
Resumen:
In the present study, a better knowledge of the influence of plasticizer content, storage relative humidity and film thickness on mechanical properties of high amilose corn starch based film gelatinized at low temperature, is presented. Mechanical properties, tensile strength and percentage of elongation at break, of high amilose corn starch films plasticized with glycerol were evaluated using tension tests. Films exhibited an increase in elongation and a decrease in tensile strength with increasing plasticizer concentration. When glycerol level was high, some fissures into drying films were detected, possible due to phase separation (starch-glycerol) phenomena. Film crystallinity is related to reorganization capacity of polymer chain, thus film relative crystallinity must increase with plasticizers content (glycerol and water). Mechanical properties were found strongly dependent on the water content due to the hydrophilic nature of starch films. The influence of moisture sorption on tensile strength was similar to plasticization with glycerol. The relation between polymer chain mobility and water content explained this behavior. Elongation suffered a different effect; maximum values were reached at 45% relative humidity. The final drop in elongation was due to structure softening at high relative humidity. As thicker the film the longer the drying time required, this leading to larger relative crystallinity due to corresponding increase of possible chain reorganization occurrence. As a consequence, a linear increase of tensile strength and elongation with film thickness, over the whole range studied (30 to 100 mm), were observed.