Encapsulation of konjac glucomannan in oil droplets to reduce viscosity of aqueous suspensions and gradually increase viscosity during simulated gastric digestion

• Konjac glucomannan (KGM) powder was encapsulated in oil droplets of S/O/W emulsions.
• Addition of lecithin in the oil phase facilitated the encapsulation of KGM.
• Preheating whey protein improved the encapsulation of KGM as low viscosity suspensions.
• Emulsions showed the gradual increase of viscosity during simulated gastric digestion.
• The viscosity increase resulted from pepsin digestion of oil droplets to hydrate KGM.

Konjac glucomannan (KGM) is a water-soluble polysaccharide with extraordinary ability to absorb water and increase viscosity and therefore a potential strategy to increase satiety and control food intake. However, it is difficult to incorporate KGM in aqueous foods without increasing viscosity significantly. In the present work, the objective was encapsulate KGM powder as the core of oil droplets in solid/oil/water emulsions to prevent the hydration of KGM and viscosity increase. Blending soy lecithin with soy oil enabled better mixing of KGM powder and oil and enabled the encapsulation of KGM powder at a sufficiently high concentration of whey protein isolate (WPI), as indicated by low viscosities. Preheating WPI reduced the amount of proteins required to encapsulate KGM. The gradual digestion of oil droplets by pepsin at simulated gastric conditions enabled the gradual hydration of encapsulated KGM powder to increase viscosity. These results suggest the feasibility of S/O/W emulsions to deliver KGM in aqueous foods without generating a high viscosity but enabling gradual increase of viscosity during gastric digestion to potentially impact satiety and food intake.