Comparative study of the rheology and texture of konjac glucomannan-xanthan gum complexes in water and simulated gastric fluid and their effect on gastric emptying

Abstract

The viscosity of natural hydrocolloids plays as an essential role in body weight loss. However, the viscosity of natural hydrocolloids may change dramatically in the complicated gastrointestinal tract, especially in mixed hydrocolloid systems where interactions occur. These changes can be flexible. Here, the rheological and textural characteristics for the combination of konjac glucomannan (KGM) and xanthan gum (XAG) in water and simulated gastric fluid (SGF), as well as the effects on gastric emptying were explored. The results showed the viscosity, elastic modulus and textural parameters (firmness, consistency, adhesiveness, and cohesion) of the high-ratio KGM/XAG complexes in water were significantly higher than those in SGF. In contrast the opposite was true for the low-ratio KGM/XAG complexes. The viscosity of the equal proportional complexes was significantly lower in water than in SGF, but the textural parameters were significantly higher in SGF than in water. The interactions between KGM and XAG were concentration-dependent, more potent at low concentrations and weaker at higher concentrations. Dynamic gastric emptying ex vivo results showed no significant difference between the complexes of different ratios, but they were significantly higher than single KGM. The high pH and viscosity of digestives were highly correlated with delayed gastric emptying. In conclusion, viscosity should be accurately described when it comes to viscosity retarding gastric emptying because of the huge difference in viscosity between water and SGF. These results contribute to a deeper understanding of the interactions between the physicochemical properties of hydrocolloids and the human body and provide a basis for the targeted design of hydrocolloid structures.