Lyophilized Powder of Hibiscus sabdariffa (Roselle) Extracts using Gum Arabic and Maltodextrin as Carrier Agents

Freeze-drying is a process for drying foods without heat application. The physical, chemical and sensory properties of the food remain without significant changes. In this work, maltodextrin (MD), gum arabic (GA), and a blend of MD-GA (60-40) were used as encapsulating agents of Roselle (Hibiscus sabdariffa) calyces extracts. Lyophilized powders were obtained at different concentrations of encapsulating agent (0, 3, 5, and 10%, w/w). Powders were analyzed in yield and physicochemical (average size diameter (d50), moisture content, water activity (aw), bulk and compacted densities, and color), and antioxidants (anthocyanins content, total phenolic compounds, antioxidant capacity) characteristics. The yields of freeze-drying powders from different encapsulating agents ranged 82 to 95%. The average diameter (d50) was higher for powders without gum (139.5±25.6 um) than for powders with encapsulating agents (35 to 89 um). The moisture content and aw of the powders were in the ranges 5.3-11.2% and 0.20-0.29, respectively. The value of the red (a*) color parameter of all powders was 37.0±2.8, decreasing as increasing the gums concentration. Powders with 3% GA and MD showed the highest amount of anthocyanins- 560.93±10.13 and 543.46±15.68 mg/100 g of powder, respectively. The highest total phenolic compounds content was observed in the powder with the 3% MD-GA blend (4,705.70±140.54 mg/100 g of powder). Powder with 3% MD showed the highest antioxidant capacity (1,766.30±31.15 mg of Trolox equivalents/100 g powder).