Novel high internal phase oleogels-in-water pickering emulsions stabilized solely by whey protein isolate for 3D printing and fucoxanthin delivery

The versatile applications of high internal phase emulsions (HIPEs) in the food industry have aroused widespread interest. However, it remained a challenge to prepare HIPEs that were solely stabilized by proteins and had desirable stability and rheological properties. Herein, stable and tailorable HIPEs stabilized solely by whey protein isolate (WPI) were prepared via oil phase gelatinization by glycerol monostearate (GM). Unlike conventional HIPEs, the small size of oil droplets (from 17.06 μm to 5.43 μm) and gel-like network structure in the oil phase, a resultant of the gelatinization of the oil phase, endow the superior stable and desirable rheological properties of our oleogels-in-water HIPEs. Oil gelation could improve the freezing-thawing stability of the oleogels-in-water HIPEs, and the appearance remained stable after six freezing-thawing cycles. The rheological properties of the oleogels-in-water HIPEs could be tailored by GM concentrations, as GM increased their viscoelasticity and recoverability, which proved the printability of the oleogels-in-water HIPEs. Moreover, the half-life of fucoxanthin in fucoxanthin-loaded oleogels-in-water HIPEs was 2.5 times higher than that dissolved in oil, the increased stability of fucoxanthin in the oleogels-in-water HIPEs was owing to the gel network structure formed by GM. In vitro digestion suggested encapsulation of fucoxanthin by oleogels-in-water HIPEs was an effective way to improve their oral bioaccessibility (28.62%–45.48%). These results demonstrated the potential of oil gelation in designing novel HIPEs for numerous food applications.