Effect of wild yam root preparation on physiochemical properties of ready-to-use wild yam flour

Abstract

Asiatic bitter yam (Dioscorea hispida Dennst.) or kloy kao niaw (KKN) is a food plant of people in the tropics, but certain wild varieties are edible after detoxified.  Detoxified of KKN are delicious food ingredients. Thus, the effects of the preparation method on the physicochemical quality of ready to used KKN flour were investigated. The KKN tubers were taken from Mae-Tha, Lampang, Thailand. The KKN was cleaned, peeled, and sliced to 0.1 mm before soaked in salt solution at 0, 10, 20, 30, 40, and 50% for 12 hours. Each treatment was washed every day for eight days or until the sliced Kloy has white color. The ready to used KKN flour was produced with three methods; soaked in 2% salt solution for 10 min, boiling for 10 min, and steaming for 30 min prior drying in tray dried at 60 ^๐C for four h then ground through 80 mesh screen and packed in an aluminum foil bag. The ready-to-use KKN flour was analyzed on % production yield, moisture content, color value, gelatinization temperature, starch granule by SEM, and pasting behaviors. Research revealed that the treatment on soaked slice KKN in 20% salt prior steam for 30 min had the highest production yield (26.8%), 7.70% moisture content.  The color L* a* b* value were 92.98, 0.15, 7.42 respectively. The selected ready to use KKN flour had low gelatinization temperature, swollen starch granules, and lowest peak viscosity, and easily soluble in water than the other two treatments.