Development of an isotonic sports drink containing carob extract and wheel protein enriched with vitamin D by nanoemulsion preparation technology

In this study, the objective was to enhance the vitamin D content of a sports drink, a functional beverage, in order to develop a natural and functional product suitable for daily consumption, providing consumers with easy access to vitamin D. In the scope of the study, traditional water-mixing methods are ineffective due to the hydrophobic nature of vitamin D. Therefore, nanoemulsion preparation technology using ultrasonication was utilized. The independent variables Tween 80 (0-2%), whey protein (WPC-70, 0-2%), and sonication time (120-300 s) were chosen, and their impacts on particle size (nm) and zeta potential (ζ, mV), key parameters for nanoemulsions, were investigated. A sonicator operating at 100 watts and a frequency of 30 kHz, requiring minimal sample volumes, was employed to attain the desired particle size for nanoemulsion. However, statistical analysis revealed that the results were incongruent with any model within the response surface method. Consequently, a subsequent experimental plan was devised, implementing a 200-watt sonicator at a frequency of 20 kHz, along with modifications to the emulsifier addition procedures. Utilizing a centralized integrated experimental design, emulsifiers Tween 80 and whey protein (WPC-70) at 1-2% and a consistent sonication time of 10 minutes were determined. This yielded a maximum particle size of 266 nm and zeta potential values ranging from -8.423 to -13.567 mV. Subsequent zeta potential and particle size analyses were conducted on samples stored at +4oCand on days 7 and 14. The initial particle size measured at 71.980 nm increased to 81.04 nm on the 7th day and 89.56 nm on the 14th day, while still retaining its nanoemulsion properties.