Microencapsulation of roselle (Hibiscus sabdariffa L.) anthocyanins: Effects of different carriers on selected physicochemical properties and antioxidant activities of spray-dried and freeze-dried powder

Abstract

Anthocyanins are abundant phytochemicals in nature that draw the public interest not only in their health effects, such as antioxidant, anti-inflammatory and anti-carcinogenic properties. It also showed their function in providing foodstuffs with appealing and distinctive color. In this study, anthocyanins from hibiscus (Hibiscus sabdariffa L.) calyces were microencapsulated by spray drying and freeze drying techniques using a wide variety of carriers including maltodextrin (MD), gum Arabic (GA) and their binary blends with inulin (INU) and konjac glucomannan (KON). The results showed that freeze-dried hibiscus powder using KON as carrier had the highest phenolic, anthocyanin and antioxidant activity, followed by spray-dried and freeze-dried MD/KON samples, which indicated the role of KON in the effective retention of antioxidants during the drying process. In addition, the ferric and cupric ion reduction activity (FRAP and CUPRAC) of the spray-dried samples was significantly higher than those of the freeze-dried powder. However, in terms of encapsulation efficiency (EE) of anthocyanins, KON was shown to be ineffective in entrapping these compounds in microcapsules with the lowest EE of freeze-dried KON and spray-dried MD/KON of 43.6% and 55.4%, respectively. By contrast, MD/GA was the most effective carrier, retaining anthocyanins inside the carrier matrix and limiting their loss to the surface of the microcapsules in both spray-drying and freeze-drying methods (EE of 91.8% and 95.7%, respectively). In addition, the moisture content of spray-dried powder samples was significantly higher than that of lyophilized powders, and the solubility of all samples was above 94.1%.

Keywords

• roselle anthocyanin
• spray drying
• freeze drying
• phenolic content
• antioxidant activity
• encapsulation efficiency