Abstract
Konjac gels were prepared by changing the conditions (temperature and concentration of calcium hydroxide (Ca(OH)2) and the stress growth and stress relaxation behavior of the resultant gels were determined. The correlation between preparation conditions and mechanical behavior and the difference in the behavior between the unpurified konjac and the purified konjac gels were discussed on the basis of the rigidity of the gels. The liquid crystal-formability of konjac mannan was also discussed based on optical measurements (polarized microscopy and circular dichroism). The conditions determined as optimum for preparing the konjac gels were that the temperature at 55°C and the Ca(OH)2 concentration of 1.2-2.4 wt%. For the gels with Ca(OH)2, the rigidity of the purified konjac gels was much higher than of the unpurified gels whereas for the gels without Ca(OH)2, the rigidity of the unpurified gels was higher than that of the purified gels. The solid films cast from purified konjac mannan exhibited a cholesteric liquid crystalline order (left-handed) whereas the films cast from unpurified konjac showed no liquid crystalline order.
