Encapsulation of betacyanins from the peel of red dragon fruit (Hylocereus polyrhizus L.) in alginate microbeads

Red dragon fruit (Hylocereus polyrhizus L.) is a rich source of betalains compounds, natural pigments with desirable bioactive and antioxidant properties. In this paper, we focused on the use of mathematical models for prediction the properties of alginate microspheres loaded with betacyanins from the peel of red dragon fruit. Besides to assess their storage and heat stability, the prepared alginate-loaded microspheres were characterized by encapsulation efficiency (EE%), particle size, uniformity and morphology. Antioxidant properties, thermal degradation kinetics of betacyanins (half-life: T-1/2) loaded in alginate and simulated gastro-intestinal (SGI) release behavior were mentioned as indices for microspheres stability. Based on the mathematical optimization, betacyanins extract was efficiently entrapped in alginate (EE% = 78. 62; mean particle size: 106.32 +/- 6.77 mu m and uniformity: 0.279 +/- 0.05) in a ratio of 1:8.97 alginate: betacyanins. The investigation of SGI release behavior of alginate-loaded betacyanins extract showed the good potential of micro-capsules as a carrier for delivery of antioxidants. The half-life (T-1/2), and total betacyanins retention (%) in microspheres during storage were also improved in comparison with non-capsulated extract and commercial betanin solution (control). Alginate microspheres loaded with betacyanins are effective models for food colourant additives and oral delivery purposes.