Alpha-amylase inhibitor changes during processing of sweet potato and taro tubers

Alpha-amylase inhibitor changes during processing of sweet potatoes (Ipomoea batatas) and taro (Colocasia esculenta) indicated that varietal differences profoundly influence the thermal inactivation profile. The alpha-amylase inhibitors of taro were almost totally inactivated during oven drying of the chips at 90 degreesC and 100 degreesC for 24h, while 0.8-10% activity was retained in sweet potato chips under the same conditions. Relatively better thermal stability was exhibited by the sweet potato amylase inhibitors at lower temperatures (70 and 80 degreesC) as well. Cooking by boiling the tuber pieces in water resulted in retention of 29-59% amylase inhibitor in sweet potato and 11-16% in taro. Microwave baking was a better method for inactivation of amylase inhibitors in these tubers. Flour prepared from the tubers retained only trivial amounts of the inhibitor.