Impacts of Konjac Glucomannan on the Pasting, Texture, and Rheological Properties of Potato Starch with Different Heat–Moisture Treatments

Abstract

Few studies reported the impact of hydrocolloid addition on starches after heat moisture treatment (HMT). In this study, potato starch is modified by HMT under different moisture content (18–35%), and the impact of konjac glucomannan (KGM) addition on the pasting, gel texture, and rheological properties of potato starch after HMT are investigated. The results showed that after HMT, the granule structure of the starch is changed with higher heat stability, shown as higher pasting temperature and trough viscosity. The impact of KGM addition is similar on the potato starch before and after HMT, but the change extent of the latter is larger in most cases, such as decreased pasting temperature and gel hardness, increased peak viscosity, breakdown viscosity, and final viscosity. This indicated that KGM benefited the gelatinization behavior of HMT starch but might not enhance the retrogradation process. The intrinsic high viscosity of KGM in water resulted in a softer starch gel and also contributed to the enhanced shear stress of the mixture paste. Therefore, the impact of KGM on the HMT starch is more significant than the original starch, and this guided the use of HMT starch in the food industry with other hydrocolloid involvement.