Making kuzu in an automated factory is still a three-month-long, expensive process. The roots must still be dug by hand and then washed, filtered, and dried to extract the starch. In comparison, starch from sweet potatoes can be extracted in just three or four days with twice the yield as kuzu.
Because of kuzu's high price, many people use potato starch as a substitute. Some kuzu manufacturers mix potato starch with the kuzu powder. Shoppers must read labels carefully to be sure they are buying 100 percent kuzu powder. Kuzu sold in American Oriental foods stores is sometimes an inferior mix of potato and kuzu starch. However, Mitoku's kuzu root powder is 100% high quality kuzu.