Characterization and properties of purple yam (Dioscorea trifida) powder obtained by refractance window drying

Abstract

Purple yam, Dioscorea trifida (DT), is characterized by its valuable nutritional properties and as powder it could be used as an ingredient in various foods. In this research, the DT paste was dried by refractance window (RW) at 70, 80, and 90 °C for 40 min, a technique for obtaining powders with microbiological stability (aw < 0.35), good fluidity and low cohesiveness. In the powders obtained from DT, carbohydrate was the major constituent (85.66 to 86.47%) with starch content higher than 69.0%. Among the technological properties, the oil absorption index of the powder was strongly dependent on the RW drying temperature. The highest retention rates of bioactive compounds (>50%) in powders occurred at temperatures of 70 and 80 °C. The drying by RW was promising and presented industrial potential to produce DT powder with technological and nutritional quality to be applied in food.