A potential natural coloring agent with antioxidant properties: Microencapsulates of Renealmia alpinia (Rottb.) Maas fruit pericarp

Abstract

Microencapsulates of ethanolic extracts of Renealmia alpinia (Rottb.) Maas fruit pericarp were obtained by spray drying. Physicochemical properties (pH, °Bx, titratable acidity, maturity index, moisture content and color), bioactive compounds (anthocyanins and other phenolic compounds) and antioxidant capacity of the fresh fruit pericarp were assessed. Microencapsulates were produced by feeding a 1:3 mixtures of ethanolic extracts (encapsulated material) and different encapsulating agents (maltodextrin, gum arabic and a 1:1 mixture of both) to the spray dryer. Physical properties (yield, particle size, moisture, color, wettability, bulk and compact densities) of the resulting powders were determined while both stability of antioxidant compounds and maintenance of antioxidant capacity were evaluated during a 28-day storage at 4 and 25 °C. Fresh pericarp was an important source of phenolic compounds and anthocyanins which heavily contributed to fruit color parameters. The highest yield 21.58% and moisture content 2.45% were observed in powders with 1:1 maltodextrin-gum arabic ratio. Gum arabic microencapsulates better preserved anthocyanins (10.37 ± 2.38, 11.65 ± 0.58, mg Cyd-3-Glu/g) and phenolic (7.58 ± 0.51, 8.70 ± 1.28 mg GAE/g) at both storage temperatures 4 and 25 °C, respectively. Two individual anthocyanins were identified by HPLC: cyanidin-3-O-glucoside and delphinidin-3-O-glucoside. While maltodextrin capsules exhibited increased stability of antioxidant compounds and activity at 4 °C storage. Evaluated microencapsulates might represent a suitable alternative as a natural coloring agent with potential antioxidant activity. Keywords: Encapsulates, Antioxidant properties, Renealmia alpinia (Rottb.) Maas, Pericarp, Spray drying, Pigment