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This research was conducted to investigate the effective methods for browning inhibition on yam (Dioscorea aimadoimo) during dehydration by physical and chemical pretreatments. Moisture, crude protein, crude fiber and N-free extract contents of yam were 81.17%, 1.43%, 0.29% and 15.81%, respectively. Yams were sliced to 0.5 ㎝ thickness and placed to singles and poly layer in plastic tray, and then changes of their weights were measured during air dehydration at 50℃, 65℃ and 80℃. The dehydration time reaching to optimum moisture level for the pulverization of the yam slices were 10, 6, 3 hours(single layered) and 12, 7, 5 hours(multi layered) at the respective temperature. To inhibit browning at 80℃ air dehydration, water and steam blanching, microwave treatment effects were investigated on yam slices for 30 sec. and 60 sec. Steam blanching for 30 sec. was comparatively effective to inhibit browning of yam slices. Yam slices were immersed in single and combined browning inhibitor solutions and evaluated for browing degree during dehydration by the values of Hunter L, a, b and △E. The most effective pretreatment to inhibit browning of yam slices was immersion in the solution containing 500 ppm of citric acid and 1000 ppm of cysteine for 1 min.
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