Rheological properties of aqueous konjac glucomannan dispersions and its mixtures with soybean protein isolate

Abstract

The properties of konjac glucomannan(KGM) aqueous dispersions and the mixtures of KGM/soybean protein isolate(SPI) were investigated by rheological measurements. It is found that the changes in storage shear modulus(G′), loss shear modulus(G″) and viscosity(η) for KGM aqueous dispersions essentially depend on the nature of the added thiourea, urea, sugar, and lyotropic series salts. The salting-out effect of adding Na₂SO₄, is quite remarkable on KGM, which increases both the G′, G″ and η of the KGM aqueous dispersions evidently whereas the effects of adding NaCl, NaNO₃ and NaSCN are not significant. In the case of mixing SPI with KGM, the addition of SPI causes a significant increase in the viscoelasticity of the mixture. This fact indicates that an interaction between the two biopolymers might be due to the occurrence of enhanced hydrogen bonding between KGM and SPI.

Keywords

konjac glucomannan / soybean protein isolate / dynamic viscoelasticity / molecular interaction / lyotropic series

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