Effects of Water-Glycerol and Water-Sorbitol Interactions on the Physical Properties of Konjac Glucomannan Films
Article first published online: 31 MAY 2006
Journal of Food Science
Volume 71, Issue 2, pages E62–E67, March 2006
How to Cite
Cheng, L. H., Karim, A. A. and Seow, C. C. (2006), Effects of Water-Glycerol and Water-Sorbitol Interactions on the Physical Properties of Konjac Glucomannan Films. Journal of Food Science, 71: E62–E67. doi: 10.1111/j.1365-2621.2006.tb08898.x
- Issue published online: 31 MAY 2006
- Article first published online: 31 MAY 2006
- MS 20050370 Submitted 6/21/05, Revised 8/10/05, Accepted 11/16/05.
- konjac glucomannan;
- edible films;
- equilibrium moisture content;
- sorption isotherm;
- tensile properties
Konjac glucomannan (KGM)-edible films were prepared with different amounts of glycerol or sorbitol as a plasticizer. Films were characterized by moisture sorption isotherm, and following conditioning at different relative humidities, by differential scanning calorimetry and tensile tests. Moisture and polyols (sorbitol and glycerol) were found to plasticize KGM-based films with respect to their tensile properties. However, thermal properties and water sorption capacity (WSC) of polyolplasticized KGM films were found to vary with water activity (aw), namely at low aw (< 0.6), WSC and melting enthalpy were decreased with increasing in polyol content and the opposite was true at higher aw (>0.6). This was attributed to extensive interactions between plasticizer and KGM that reduced the available active site (-OH groups) for water adsorption. The presence of polyols at low aw appeared to suppress crystalline structures due probably to restricted molecular mobility. These effects were diminished when the moisture content was >20%.