Stabilization of the bioactive pigment of opuntia fruits through maltodextrin encapsulation.

Betalains are water-soluble, nitrogen-containing pigments of growing interest in the food industry. They are present in most plants belonging to the order Caryophyllales, where they fulfill the role of anthocyanins, and are divided into two groups: violet betacyanins and yellow betaxanthins. They are bioactive molecules that account for health-promoting properties, recently described for cactus pears (Opuntia). In this work, the characteristic betalain of cactus pears, indicaxanthin, is obtained purely, and its stability is highly promoted by its encapsulation in a maltodextrin matrix. A suitable spray-drying procedure for encapsulation is described, and a bright yellow powder is obtained. The stability is analyzed under different conditions. In the absence of light, pure encapsulated pigment can be stored at 20 °C for months without appreciable loss of the bioactive substance and color variation. Furthermore, free radical scavenging and antioxidant properties of the pigment are studied under the ABTS(•+) radical and ferric reducing antioxidant power assays, in the presence and in the absence of maltodextrins. The stabilization of pure betalain pigments may boost the use of these bioactive and natural coloring molecules.