Dissolution and rheological behavior of deacetylated konjac glucomannan in urea aqueous solution.

Deacetylation adversely affected the solubility of konjac glucomannan (KGM). Herein the dissolution behavior of deacetylated KGM (da-KGM) was studied in 10 wt% urea solution at various temperatures. KGM with different degrees of deacetylation (DD) could be well dissolved at -4°C. Low temperature was conducive to the dissolution of da-KGM. The result from steady shear showed that the zero-shear viscosity decreased with the increase of DD, with the rheological model being conformed to the Cross equation. Dynamic viscoelastic properties indicated the da-KGM gel formed more easily with increasing concentration, or decreasing temperature and DD. Temperature sweep revealed that gel process could be divided into two stages. The first stage was that both storage modulus (G') and loss modulus (G″) fell until the temperature reached 90°C. The second stage was that G' and G″ increased abruptly, presenting the transition from sol to gel.