Characteristics of pullulan-based edible films
K. C. HEO, J. J. Lee, S. Y. Park, and J. W. Rhim. Department of Food Engineering, Mokpo National University, 61 Dorimri, Chungkyemyon, Muangun, Chonnam, 534-729, South Korea
Pullulan is an extracellular bacterial polysaccharide produced from starch by Aureobasidium pullulans. It is a linear polysaccharide made up of ес–1,6-linked maltotriose residues. As an odorless white colored powder, pullulan is easily soluble in water to make clear and viscous solution. This polymer also has high adhesion, sticking, lubrication, and film forming abilities.
The main objectives of this study were to prepare pullulan-based edible films with or without gelling agents such as carrageenan, alginate, gellan, and agar and to determine some selected properties like tensile strength (TS), elongation at break (E), water vapor permeability (WVP), and water solubility (WS) of the films.
5 g pullulan was dissolved into 150 ml distilled water to make a clear solution. The film solution was casted onto a leveled Teflon-coated glass plate and dried at room temperature for 24 h. In addition, pullulan films were prepared with gelling agents with 5-10% of pullulan by weight. TS and E of the films were measured using an Instron Universal Testing Machine and WVP was measured by the gravitational method using a water vapor permeability cup.
Transparent pullulan films with or without gelling agents were prepared. WVP, WS, TS and E of pullulan films were 0.69x10-9 g.m/m2.s.Pa, 92.4%, 45.0 Mpa and 4.0%, respectively. Physical properties of pullulan films were greatly affected by adding gelling agents. As a whole, TS increased by adding gelling agents without significant change in E. Though WS of the films decreased by adding gelling agents, WVP increased. Among the gelling agents tested agar was the most effective to increase TS and gellan was the most effective to reduce WS of the pullulan-based films.
Free standing films were prepared with pullulan and their properties could be properly modified by adding various gelling agents.
Session 73D, Food Packaging