Sweet potato (Ipomoea batatas L.) used for the drying experiments were obtained from a local market at Pantnagar, Uttarakhand (India) and stored in a refrigerator at 4 ± 0.5 ◦C for 48 h. Prior to drying, the pointed ends were trimmed with knife and peeling was done manually with sharp stainless steel knife. Then, sweet potato cubes were blanched in hot water at 80 ◦C for 25 min and cut into cubes of 5, 8 and 12 mm thick using cutting machine. Sweet potato was soaked in 0.5:1% (w/w) KMS:citric acid solution at 50 ◦C for 10 min to avoid undesirable changes during drying and to preserve quality of dried product during storage. The water was drained out completely and the cubes were kept under shade for about 30 min to remove surface moisture. Finally, the samples were kept in the dryer for drying on the same day. Sample size was kept constant at 500 g for all runs. The initial moisture content of sweet potato prior to drying was determined by hot air oven