Effect of spray drying conditions on the antioxidant and physicochemical properties of clinacanthus nutans leaves extracts

Abstract

Clinacanthus nutans is a medicinal plant with valuable health benefits enriched with polyphenols and flavonoids. The aim of this work was to produce spray-dried powder from C. nutans leaves using combination of κ-carrageenan (κC) and sodium carboxymethyl cellulose (NaCMC) as coating agents and to evaluate the effects of feed flow rate, inlet air temperature and concentrations of coating agent. The effects of spray drying conditions on the encapsulation yield, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, total phenolic content, total flavonoid content and four C-glycoside flavones (orientin, isoorientin, vitexin, isovitexin) of C. nutans powder were assessed for different feed flow rate (500 - 900 mL/h), inlet air temperature (110 - 150 °C) and different volume ratio of extract to coating agent (1 : 1 - 1 : 10). The result showed that vitexin was the major C-glycoside flavones compound detected in the extract. The highest encapsulation yield and antioxidant activity of the spray-dried powder was obtained from the inlet temperature of 130 °C with feed flow rate of 700 mL/h and 1 : 5 ratio (volume ratio of C. nutans extract to carrier solution). The spray-dried C. nutans had a regular spherical shape with particle size of 2.71 - 5.88 μm. In comparison to uncoated extract, the encapsulated powder showed significant improvement in particle size and antioxidant capacity. These results demonstrated that the spray-dried of C. nutans with high preservation of antioxidants is a promising source of natural products with diverse opportunities for nutraceutical and functional food applications.