Confirmation and measurement of hydrophobic interaction in sol-gel system of konjac glucomannan with different degree of deacetylation

Fluorescence measurement was used as a tool to study the hydrophobic interaction in sol-gel system of konjac glucomannan (KGM) with different degree of deacetylation (DD). In the concentration from 0 to 10 g/L, I1/I3 ratio of native KGM declined from 1.75 to 1.25. Before and after heating, the critical associating concentration of the native KGM was 0.60 g/L and 0.95 g/L respectively, but this value of deacetylated KGM (DD = 32.58%) was 0.58 g/L and 0.45 g/L respectively. The addition of Na2SO4 and NaSCN exhibited more significant influence on deacetylated KGM compared with native KGM. All the phenomenons correlated well with the theory of salting in and salting out, indicating that the difference of DD leaded to the diversity of intramolecular and intermolecular forces in KGM solutions, namely, as DD increased, the contribution ratio from hydrophobic interactions grew up compared with hydrogen bonding.