Solution property of low molar mass Konjac mannan

Makabe, Takeshi*; Prawitwong, P.*; Takahashi, Ryo*; Takigami, Machiko*; Nagasawa, Naotsugu; Takigami, Shoji*

Konjac mannan (KM) is a water soluble glucomannan with high molar mass. KM aqueous solution shows extremely high viscosity. The effects of -rays irradiation and acid hydrolysis on molar mass were studied. The hydrolysis was carried out using citric acid. Characteristics of the irradiated and hydrolyzed KM were investigated using GPC-MALLS and a viscometer. The chemical structure of KM scarcely changed by both treatments. Molar mass of the irradiated KM decreased gradually with increasing dose. Molar mass of the hydrolyzed KM also decreased gradually with acid concentration. The viscosity of both treated KM aqueous solutions decreased with decreasing molar mass. High molar mass KM solution showed pseudo-plastic fluids behavior of the non-Newtonian fluid at dilute region and changed to Newtonian fluid with decrease of molar mass. Low molar mass KM solution showed behavior of Newtonian fluid at semi-dilute region. The critical concentration at the overlap limit of KM solution increased with decreasing of molar mass.