Effects of blanching, drying and extraction processes on the antioxidant activity of yam (Dioscorea alata)

Abstract

[[abstract]]The effects of blanching, drying and extraction processes on the antioxidant activities of one kind of Taiwanese yam peel, Darsan (Dioscorea alata), were investigated. The antioxidant measurements included total phenolic content, reducing power and alpha ,alpha-diphenyl-beta-pricryl-hydrazyl (DPPH) radical-scavenging activity. The 50% ethanolic, hot water and water extracts from the peel all had much higher antioxidant activities than those extracts from the flesh. Among three extraction methods, 50% ethanolic extraction resulted in the highest antioxidant activities in the peel, while hot water extraction was more appropriate for the flesh. Blanching by immersing the peel in 85 degrees C water for 30 s caused significant reductions in the antioxidant activities of all the extracts from the peel. Generally speaking, freeze-dried peel maintained higher antioxidant activities than hot air-dried peel