Many people confuse Okinawan sweet potatoes and ube yams because of their rich purple color, so we wanted to share some of the major taste, nutrition, and biological differences and similarities between these two crops. Even with their differences, substituting purple sweet potatoes for ube works great in a pinch–only a true connoisseur will taste the subtle difference!
Okinawan Sweet Potato
ʻUala, or sweet potatoes, were brought to Hawaiʻi by Polynesian voyagers, with over 200 varieties of ʻuala farmed in Hawaiʻi before European contact! The Okinawan sweet potato variety originated in South America and was brought to Japan in the 1600’s, with the first plantings in Okinawa. The purple tubers were then brought to Hawai‘i with Japanese sugar plantation workers in the early 1900s, and have since become a local favorite.
Known as “ube” in Tagalog, the national language of the Philippines, as well as “winged” or “water” yam in English, this purple yam is native to Southeast Asia and has become naturalized in South America, Africa, Australia, and the southeastern United States. Uhi, the Hawaiian edible yam, is a canoe crop of the same species as ube (Dioscorea alata). Very popular in the Philippines, ube is used in many traditional dishes and modern desserts like ice cream and cake. Interested in growing ube? Check out HIP Agriculture’s informative planting video to learn about growing your own ube!
Taste and Texture
- Both ube and Okinawan sweet potato have a similar sweet, earthy flavor, with ube carrying hints of pistachio and vanilla.
- Sweet potatoes have a drier texture while ube is more moist; some have even likened ube to an Irish potato!
- In Hawaiʻi, one traditional differentiator between sweet potatoes and yams is that ʻuala can be made into poi by adding water while uhi is not sticky enough and too mealy.
- Why are ube and Okinawan sweet potatoes both so purple? Their purple coloring actually comes from anthocyanins, powerful antioxidants which help to guard against cardiovascular disease and cancer.
- Uhi never achieved staple food status in Hawaiʻi while ʻuala was an important staple crop.
- Okinawan sweet potato has a lower Glycemic Index than ube does (46 vs.79), meaning it is less likely to cause large increases in blood sugar levels and may support weight loss and prevent chronic diseases related to obesity – such as diabetes and cardiovascular disease.
- The skin of purple sweet potatoes is thin, like an Irish potato, and can be eaten; but ube has a thick, bark-like skin, allowing the crop to store for longer.
- Okinawan sweet potatoes are in the morning glory family and completely unrelated to yams.
- Yam like ube and uhi take a full year’s cycle to grow a crop while purple sweet potatoes mature quickly, in just about 3 to 7 months.
While ube may be hard to find, boosting your diet with nutritious bright purple colors is easy with our steamed and frozen ʻuala. Check out our home recipe for Farm-to-Table Sweet Potato Gnocchi for a rich dish packed with antioxidants that is simple to make!