Development of a whey protein hydrogel as an alternative for the microencapsulation of calyx extracts from Hibiscus sabdariffa

The aim of the present work was to develop a hydrogel based on whey protein as an alternative for stabilizing anthocyanins from roselle (Hibiscus sabdariffa L.) calyces, which have potentially beneficial effects on human health but are susceptible to degradation and oxidation reactions during processing and storage. Concentrated extracts were prepared and then microencapsulated using the emulsification technique in order to obtain hydrogels, which were then physiochemically characterized and stored for three weeks at 4ºC where their color properties were monitored. The extracts exhibited a concentration of 81.37 ± 2.63 mg of cyanidin-3-glucoside per L, as well as a hue angle of 6.86 ± 0.52, both consistent with the literature for Jamaica-based products. The hydrogels obtained showed a high moisture content and water activity (82.22 ± 1.0% and 0. 93 ± 0.003, respectively) due to their tendency to store water up to 100 times their weight, while the particle size ranged from 8.75 ± 1.70 to 15.15 ± 2.19 µm; a decrease in color properties related to the incorporation of the pigment into the hydrogel was observed, as well as a decrease in bioactive compounds due to the effect of the processing steps. During storage, a 32.94 ± 3.72% decrease in red shades and a 27.10 ± 1.47% increase in yellow shades was observed, a change that was noticeable according to the total color difference scale, ΔE (ΔE=8.43 ± 1.69). The results of this study provide a novel alternative for the microencapsulation of bioactive compounds through the use of protein-based carrier systems, relevant for the development of innovative encapsulation systems.