STRUCTURAL AND RHEOLOGICAL PROPERTIES OF A GEL POLYSACCHARIDE FROM UMBILICARIA ESCULENTA GROWN IN HUANGSHAN MOUNTAIN

摘要

One fractional polysaccharide (HSSEP2) was isolated from the Umbilicaria esculenta grown in Huangshan Mountain. The structural and rheological properties of HSSEP2 were investigated. Methylation and NMR analysis showed that HSSEP2 had a beta-D-(1 - 6)-glucan backbones without side chains. The intrinsic viscosity was 47.7 cm(3)g(-1) at 25 degrees C. The rheological studies indicated that the HSSEP2 solution was pseudoplastic fluid and presented the properties of gels. The HSSEP2 solutions exhibited certain temperature stability when the temperature was under 40 degrees C. The metal ions had a significant impact on the rheological properties of HSSEP2 in solution. Bivalent cation had more significant effect on the modulus of HSSEP2 solutions than the monovalent cation. Low concentration of NaOH solution could improve the viscosity and modulus but destroyed the structure of HSSEP2 with high concentration. HSSEP2 exhibited gel properties suggesting that it might be a potential supplement in food industry.