Advanced Materials From renewable Resources: Konjac/pullulan Blends

摘要

Biopolymers from renewable resources have, become increasingly important in the development of advanced materials that exhibit a high susceptibility to microbial attack, Pullulan is a water soluble extracellular neutral glucan synthesized by the fungus Aureobasidium putlulan. It is a linear, high molecular weight glucan which consists of maltotriose repeating units linked by a-(l —>6) glycosidic bonds (1). It is difficult to process pullulan by conventional melt processing techniques (2). Nevertheless, the processability of pullulan has been demonstrated in the presence of plasticizers including water, ethylene glycol, and glycerol (3). Konjac glucomannan (KGM) is a natural water soluble polysaccharide found in the tubers of the Amorphaphallus konjac plant. It is comprised of 13-1,4 linked mannose and glucose units with a low degree of acetyl groups (4). The liquid crystalline behavior of KGM has been observed in aqueous solutions with concentrations above 7% (w/w) (5). Advanced materials from renewable resources can be obtained by processing the KGM polysaccharide from a liquid crystalline state. We have observed that KGM becomes insoluble in water upon drying after aqueous processing and therefore shows promise as a packaging and coating material for food and drug use. In this study, the mechanical properties and water sorption was measured for films prepared from konjac and pullulan blends containing glycerol.