Microencapsulation of Betacyanin from Dragon Fruit (Hylocereus polyrhizus) Peel by Foam-Mat Drying for Natural Food Colorant Application

Abstract

The growing demand for natural food colorants highlights the potential of betacyanin, a red-violet pigment from dragon fruit (Hylocereus polyrhizus) peel, valued for its antioxidant, anti-inflammatory, and anticancer properties. However, its application is limited by sensitivity to heat, light, and pH variations. This study aimed to enhance the stability and usability of betacyanin as a natural food coloring agent through microencapsulation using the foam-mat drying method. The extraction process was optimized using ultrasound-assisted extraction with a Box-Behnken Design (BBD) 3 levels (X1: temperature; X2: solvent concentration; X3: solid to solvent ratio) and a total of 15 experiments to maximize total betacyanin content and color intensity. Foaming agents were screened, with SP exhibiting the highest foam expansion and stability among commercial foaming agents. The foam was subsequently dried at 60℃ under vacuum to produce a stable, bioactive powder. The foam-mat drying resulted in encapsulated betacyanin with favorable properties, including high solubility of around 80% and encapsulation efficiency of up to 85%, making it suitable for applications in the food industry as a natural coloring agent. Moreover, foam-mat microencapsulation is more cost-effective and easier to implement than microencapsulation using spray drying.