Rheological and Tribological Properties of Konjac Gum-Lecithin Composite System: Effect of Incorporation of Saliva and Friction Surface Properties

Abstract

This research explored the development of composite systems using konjac gum (KGM) and soy lecithin at concentrations of 1% KGM–0.01% lecithin and 1% KGM–0.2% lecithin. The study investigated the influence of both oral and artificial saliva on the rheological and tribological properties of these systems, as well as the lubrication on different friction surfaces with varying characteristics. It has been found that different friction surfaces exhibited distinct morphological features and roughness values, significantly impacting surface wettability when treated with saliva. The viscosity of KGM–lecithin composite systems increased slightly compared to KGM hydrogel. However, adding oral or artificial saliva led to a noticeable decrease in viscosity. Lecithin did not significantly alter the viscoelastic properties of KGM gel, but the incorporation of artificial and oral saliva introduced some changes. CLSM images showed that the stability and distribution of lecithin within the composite system varied with lecithin concentration and saliva type, with artificial saliva ensuring a stable and even distribution, while oral saliva caused aggregation and irregular distribution. Furthermore, the study found that the lubrication performance of the KGM-lecithin system was influenced by the properties of the friction surface, with hydrophilic rough surfaces providing superior lubrication compared to rough surfaces. The addition of lecithin enhanced lubrication across all tested surfaces, and artificial saliva surpassed oral saliva in reducing friction coefficients. These findings offer valuable insights into the potential use of KGM-lecithin composite systems as fat mimetics, particularly in enhancing lubrication for various applications.