Effect of different drying methods on the water soluble total phenolics and flavonoids contents, and antioxidant activities of Sunchoke (Helianthus tuberosus L.) powder

Abstract

The effect of different drying methods on the water soluble total phenolics, flavonoids contents and antioxidant activities in sunchoke (Helianthus tuberosus L.) powder were investigated. Three different drying methods were shade, sun and oven at 60 °C for 12 h. The Helianthus tuberosus L. powder (2 g) was extracted by water as extracting solvent with control 80 °C for 45 min. Total phenolic contents, total flavonoid contents and antioxidant capacity were measured using DPPH free radical scavenging activity, total antioxidant capacity, ABTS free radical scavenging activity, reducing power and ferrous ion chelating effect. Total phenolic contents (1.463 ± 0.005 mg GAE g^-1 powder), total flavonoid contents (0.341 ± 0.003 mg QE g^-1 powder), DPPH free radical scavenging activities (0.488 ± 0.006 mg AAE g^-1 powder), total antioxidant capacities (68.073 ± 0.521 mg AAE g^-1 powder) and ABTS free radical scavenging activities (1.473 ± 0.066 mg AAE g^-1 powder) in the shade dried Helianthus tuberosus L. powder were higher than the sun and oven dried powder. Reducing power (OD 0.221 ± 0.003) and ferrous ion chelating effect (82.852 ± 0.727%) in the oven dried Helianthus tuberosus L. powder were higher than sun and shade dried powder.