Film-forming Characteristics of Starches

摘要

Our objective was to understand the film-forming characteristics of amylose, amylopectin, and high-amylose (55%) starch solutions at ambient environment. By using an inverted phase-contrast microscope connected to an imaging system, we were able to record and analyze the microstructural evolution of starch throughout the process of film formation. The results of image analysis suggested that the coil-to-helix transition, followed by the helices aggregation, dominated the initial stage of starch film formation from solutions, although the time when these phenomena occurred depended on the amylose content. Fresh amylose films exhibited an assembly of giant dendrites with quarternary branches. In contrast, amylopectin films showed a structure of networked clusters. Interestingly, the high-amylose (55%) starch film showed a heterogeneous structure with both amylose-rich and amylopectin-rich phases, which are integrated seamlessly by the intermo-lecular interaction between amylose and amylopectin.