Konjac glucomannan and curdlan modulate the rheological properties and digestive behaviors of oil-in-water emulsions during in vitro gastrointestinal digestion

With the rising demand for healthier food options, this study addresses the gap in understanding how the combination of konjac glucomannan (KGM) and curdlan (CUD) can enhance the stability and lipid digestion behavior of reduced-fat oil-in-water (O/W) emulsions. KGM, derived from konjac plants, and CUD, produced by Alcaligenes faecalis, are dietary fibers known for their ability to enhance food texture and rheology. Four 20 wt.% O/W emulsions with different aqueous phase compositions were prepared: (i) KGM emulsion (containing 0.8 wt.% KGM), (ii) CUD emulsion (containing 0.8 wt.% CUD) (iii) KGM-CUD emulsion (0.4 wt.% KGM and 0.4% CUD in the aqueous phase), and (iv) KGM + CUD mixed emulsion (equal volumes of individual KGM and CUD emulsions). The KGM emulsion exhibited the highest viscosity at low shear rates (0.1 s⁻¹ - 0.2512 s⁻¹), while the CUD emulsion showed higher viscosity at higher shear rates (0.2512 s⁻¹ - 39.81 s⁻¹). Among the emulsions, the KGM-CUD emulsion displayed the highest viscosity during GIT digestion, particularly under gastric conditions, and maintained a nearly constant particle size, indicating microstructural stability. Accordingly, free fatty acids (FFAs) released (%) at the end of intestinal digestion followed the order: KGM (63.55%) > KGM + CUD (42.43%) > KGM-CUD (40.85%) > CUD (36.30%). This study highlights the potential of KGM-CUD mixtures to modulate the digestion of lipid emulsions, offering valuable insights for the development of healthier food products with reduced lipid digestibility.