pH-responsive delivery of rebaudioside a sweetener via mucoadhesive whey protein isolate core-shell nanocapsules

Rebaudioside (Reb A) is a natural high-intensity sweetener available for commercial use. Its application has been hampered, however, by its unnatural sweetness profile and a bitter aftertaste at higher concentration thresholds. The goal of this research was to mitigate these shortcomings by increasing the sweetening power, thus lowering the amount needed to achieve the desired sweetness, specifically in acidic liquid media. We achieved the stated goal via the fabrication of a mucoadhesive delivery vehicle that can be retained on the tongue mucosa and allowed for a more targeted and prolonged release of the sweetener near the taste bud. We have chosen hydrolyzed whey protein isolate and pectin as shell materials and crosslinked them via an ultrasonic process. In the pursuit of our goal, we found that WPI-Pectin was the most suitable of all the protein-polysaccharide combinations tested, yielding nanocapsules with average particle sizes of 393 nm and polydispersity index (PDI) of 0.43. These capsules could be resuspended in water with ζ-potential of −20.4 mV. The WPI-pectin system was also shown to be twice as effective at depositing Reb A to the surface of the tongue as regular sweetener solution. Finally, we have demonstrated that WPI and pectin capsules can achieve a desirable pH-responsive profile for application in beverages with minimal release in acidic conditions (7.1 %) and higher release in neutral conditions (19.5 %).