A novel strategy to maintain the long-term viscosity stability of konjac glucomannan hydrosol by using zinc ion

Abstract

The viscosity of konjac glucomannan (KGM) hydrosol dropped sharply after a period of approximately 12 h. This is a well-known problem which producers are trying to solve. Several salts were added to KGM hydrosols to attempt to improve the long-term viscosity stability of KGM hydrosol. Compared with native KGM hydrosol and KGM hydrosol with Ca2+ and Mg2+, the initial apparent viscosity of KGM hydrosol with Zn2+, in the form of zinc chloride was higher, and the long-term viscosity stability was also significantly increased. This was attributed to Zn2+ preventing the degradation of KGM induced by microbial growth. Bacillus and Paenibacillus were “culprits” in the viscosity reduction of KGM hydrosol. Zn2+ maintained the long-term viscosity stability of the hydrosol by inhibiting microbial growth and enzyme activity of β-mannanase. Zinc sulfate, zinc acetate, and zinc gluconate being edible salts were also used as a source of zinc ions and showed a similar long-term stabilization effect on the viscosity of the KGM hydrosol. These provided a realistic strategy to replace non-edible additives with edible zinc salts for food industry applications.