Encapsulation of vitamin C in a rebaudioside-sweetened model beverage using water in oil in water double emulsions

In this work, vitamin C (VC) was encapsulated in a sugar-free rebaudioside-sweetened model beverage using water in oil in water (W1/O/W2) double emulsions (DEs). One- and two-step preparation methods were utilized for development of DEs. Various parameters including physical instability at different temperatures (4, 25 or 40 °C), centrifugal instability, particle size, pH, electrical conductivity (EC) and VC release from the internal aqueous phase (W1) were investigated during 30 d storage. The physical instability (i.e., formation of a less turbid subnatant) was dependent on the storage temperature and VC loading. However, it was not observed in DE samples developed by two-step method during 30 d storage at 4 °C. Particle size, EC and pH of DEs developed in two steps were lower than those prepared in one step. Two-step production method resulted in higher entrapment efficiency and stability. The chemical stability of VC encapsulated within DEs was significantly better than its stability in the continuous phase of an O/W simple emulsion. The degradation of encapsulated VC (in DEs) followed first-order reaction kinetics. The results of this study showed that VC can be efficiently entrapped within DEs developed by two-step method.