Shear-induced synergistic effects of konjac glucomannan and waxy potato starch on viscosity and gel strength

Waxy potato starch (WPS) forms a highly viscous and elastic gel under a long-term low shear at a low temperature (24 h, 20 s(-1,) and 5 degrees C), and the gel elasticity and storage modulus (G ') increase with the addition of konjac glucomannan (KGM). In this study, a relatively short-term (10 h) of low shear (20 s(-1)) was applied to the WPS dispersion with the addition of three different KGMs. With a constant low shear, viscosities of KGM/WPS dispersions initially decreased (0-4 h) followed by an increase (4-10 h) back to the level of the initial viscosity. Shear-induced WPS gel formation was accelerated by addition of KGM. The G' of KGM/WPS gel increased 25 times after shearing for 10 h and was 5 times higher than shear-induced WPS gel, which was caused by the formation of intermolecular double helices of WPS (melting Delta H approximate to 5 J/g; Delta G'(25-95 degrees C) approximate to 1100 Pa). Strong shear induced synergistic effects with KGM and WPS were observed in the viscosity and G', which was independent of the viscosity and elasticity of KGM dispersion.

Automated summary

This study investigated the effects of konjac glucomannan (KGM) on the gel formation of waxy potato starch (WPS) under low shear. The results showed that KGM accelerated the gel formation process and enhanced the elasticity and storage modulus of the gel. Strong synergistic effects of shear and KGM on the viscosity and storage modulus were observed during the gel formation process, independent of the properties of the KGM dispersion.