Health-promoting bioactivities of betalains from red dragon fruit (Hylocereus polyrhizus (Weber) Britton and Rose) peels as affected by carbohydrate encapsulation

BACKGROUND: Betalains, which are red-purple and yellow pigments, are ideal alternatives to synthetic colorants as they possess strong coloring potential and excellent health-contributing properties. However, the instability of betalains toward normal storage and biological conditions, in addition to the limited number of betalain sources, impedes their food application and diminishes their bioactivities. This study aimed to evaluate the health-promoting bioactivities of betalains from red dragon fruit (Hylocereus polyrhizus (Weber) Britton and Rose) peels as affected by encapsulation in maltodextrin-gum Arabic and maltodextrin-pectin matrices. RESULTS: Encapsulation in maltodextrin-gum Arabic and maltodextrin-pectin matrices afforded dry betalain powders after lyophilization. Optical microscopy imaging showed that the betalain powders consisted of matrix-type and shard-like microparticles. ABTS antioxidant assay revealed that maltodextrin-gum Arabic-betalain (MGB) and maltodextrin-pectin-betalain (MPB) microparticles possessed higher antioxidant capacities (195.39 +/- 8.63 and 201.76 +/- 4.06 mu mol Trolox g(-1) microparticles respectively) than the non-encapsulated betalain extract (151.07 +/- 2.57 mu mol Trolox g(-1) extract). Duck embryo chorioallantoic membrane (CAM) vascular irritation assay showed that the anti-inflammatory activity of encapsulated betalains was five-to six-fold higher than that of non-encapsulated betalains (P = 0.05). Antiangiogenic activity, as evaluated by duck embryo CAM assay, was enhanced two-to four-fold by carbohydrate encapsulation. Glutathione S-transferase (GST)-inducing activity of betalains was likewise improved four-to five-fold. CONCLUSION: The study showed that the antioxidant, anti-inflammatory, antiangiogenic and GST-inducing activities of betalains from red dragon fruit peels were enhanced through carbohydrate encapsulation. (C) 2016 Society of Chemical Industry