Alteration in rheological and digestive properties of O/W emulsions using controlled aggregation of konjac glucomannan and xanthan gum in aqueous phases

The modulation of lipid digestion and emulsion stability remains a pivotal area of research, crucial for developing healthier food products with enhanced sensory and nutritional attributes. This study investigates the influence of konjac glucomannan (KGM) and xanthan gum (XG) on oil-in-water (O/W) emulsions throughout simulated gastrointestinal tract (GIT) digestion, focusing on rheological properties, microstructure evolution, and lipid release kinetics. Three distinct O/W emulsions were formulated with 20 wt% oil content, incorporating either 0.8 wt% XG, a 1:1 mixture of KGM and XG (KGM/XG), or a blend of KGM-XG. Rheological assessments revealed all emulsions exhibited shear-thinning behavior across applied shear rates (0.1–100 1/s). During gastric and small intestinal digestion phases, the KGM-XG emulsion exhibited significantly higher viscosity at higher shear rates (2.512–100 1/s), indicating robust molecular interactions between KGM and XG under digestive conditions. The analysis of microstructure, particle size, and flow behavior showed that the KGM-XG emulsion exhibited significantly (p < 0.05) higher viscosity and smaller particle sizes compared to other systems throughout the digestion process. This finding indicates that KGM-XG emulsion demonstrates a strong resistance to enzymes and digestive fluid during the transition from oral to small intestinal phases. Importantly, the extent of free fatty acid (FFA) release at the end of the small intestinal phase was highest for XG (34.4%), followed by KGM/XG (15.65%) and KGM-XG (13.23%). These findings highlight the potential of KGM-XG emulsions to modulate lipid digestion kinetics, offering applications in designing emulsion-based foods, such as sauces, beverages, and reduced-fat foods.