Properties of Gels Formed by Heat Treatment of Curdlan, a Bacterialβ-1,3 Glucan

Curdlan is produced by a mutant of Alcaligenes faecalis var. myxogenes, strain 10C3. The nature of its gel formation was investigated. The polymer formed a firm, resilient gel when heated in aqueous suspension at or above 54°C. An aqueous suspension (2%) of the polymer gave 730 (g/cm2) gel strength when heated at 90°C. The gel strength was independent of the incubation time but dependent upon the temperature. The presence of borate alone greatly increased the gel strength. The gel strength did not change between pH 2.5 and 10. The addition of urea, a reagent which breaks hydrogen bonds, caused a decrease in the gel-forming temperature, the extent of decrease depending upon the concentration of urea. X-ray studies indicated that heat-treatment of the polymer suspension caused a change in the molecular arrangement.