EFFECT OF HEATING ON FORMATION OF CURDLAN GELS

The characteristics of curdlan preparations that were dehydrated after heating at various temperatures in water were examined by X-ray diffr action, differential scanning calorimetry and electron microscopy. X-R ay diffraction patterns showed that crystallinity was higher in prepar ations heated to above 80 degrees C, with heated preparations at 170 d egrees C having the highest crystallinity. Differential scanning calor imetry showed that the temperature of the endothermic peak caused by s welling decreased and that the peak area became smaller with increasin g heating temperatures. Moreover, preparations of (1 --> 3)-beta-D-glu cans of low molecular mass, <(DP)over bar>n 131 and 49, with and witho ut heating at 120 degrees C gave similar X-ray diffraction patterns an d differential scanning calorimetry curves to those of the original cu rdlan. The crystallinity was particularly high without heating in the preparation of <(DP)over bar>n 49 though the endotherm associated with the breakage of hydrogen bonds was lower and the enthalpy smaller tha n found for the original curdlan. Electron microscopic studies showed that longer and wider microfibrils were formed in curdlan gels, while shorter microfibrils or crystals were formed with the lower molecular mass samples of (1 --> 3)-beta-D-glucan, which are incapable of formin g gels.