Mechanical and microstructural characterization of films prepared by thermal or cold gelatinization of non-conventional starches

ROMERO BASTIDAS, C.; BELLO-PEREZ, L.A.; GARCIA, M.A.; MARTINO, M.N.; SOLORZA-FERIA, J.; ZARITZKY, N.E.

CARBOHYDRATE POLYMERS

Año: 2005 vol. 60 p. 235 - 244

0144-8617

Edible films were developed using different starch sources: banana (Musa paradisiaca), okenia (okenia hypogaea) and mango (manguifera indica). Starch suspensions were cold gelatinized with NaOH or thermal gelatinized. Glycerol was used as plasticizer. Film microstructure were characterized by X-ray diffraction, Scanning Electron Microscopy (SEM). Color, water solubility, thickness and water content of films were measured. Water vapor permeability determinations and mechanical analyses were performed. Gelatinization method has a great influence on both microstructural and functional properties of films. Starch films made by thermal gelatinization were more homogeneous than those made by cold gelatinization. All films were transparent even though cold gelatinization method led to slight opacity compared to thermal gelatinized films. Cold gelatinized films were the most soluble and crystalline. Films made by cold gelatinization have lower water vapor permeabilities than those made by thermal gelatinization. Both gelatinization methods led to films with good puncture and tensile mechanical properties within the range of other biopolymers.