STRUCTURE, MECHANICAL AND BARRIER PROPERTIES OF AMYLOSE AND AMYLOPECTIN FILMS

The effect of film formation conditions on structure, mechanical prope rties and barrier properties of amylose and amylopectin films was stud ied. The films were prepared by solution-gel-casting of amylose and am ylopectin from potato, with or without the addition of glycerol as pla sticizer. Transmission electron micrographs showed that the network st ructure characteristic for the amylose gel was also found in the film state. The amylose films without glycerol plasticization exhibited a r elatively high degree of B-type crystallinity, as revealed by wide-ang le X-ray diffraction, whereas the unplasticized amylopectin films were amorphous. Although the addition of glycerol did not affect the cryst allinity of the amylose films, glycerol-plasticized amylopectin formed B-type crystallinity, and the degree of crystallinity was dependent o n the air humidity during film formation. The degree of crystallinity affected the mechanical properties of the amylopectin films, whereas t he mechanical properties of the amylose films were influenced by the n etwork microstructure. Oxygen and water vapour permeabilities were dep endent neither on the degree of crystallinity in the films nor on the network structure. (C) 1998 Elsevier Science Ltd. All rights reserved.