The term “yam” is one of the most common misnomers in the American grocery store. While many shoppers associate the word with the orange-fleshed vegetable they buy for holiday recipes, the reality is that the vast majority of produce labeled “yam” in the United States is actually a variety of sweet potato. True yams are a botanically distinct root vegetable, native to Africa and Asia, that are typically drier, starchier, and far less sweet than the sweet potatoes they are often confused with.
True Yams vs. Sweet Potatoes: A Clarification
For most people in the U.S., the search for the sweetest type of yam is really a search for the sweetest type of sweet potato. The confusion dates back to the 1930s, when Louisiana sweet potato growers marketed their new orange-fleshed varieties as “yams” to differentiate them from the more traditional pale-fleshed versions. This marketing trick has stuck, and now even the USDA requires that any products labeled “yams” also include the term “sweet potatoes”.
Here are the key differences:
- Sweet Potatoes (Ipomoea batatas): These are root vegetables belonging to the morning glory family. They have smooth, thin skin that can range in color from tan to red or purple, and flesh that is orange, white, or purple. Sweet potatoes have a naturally sweet flavor and moist texture, which is enhanced during cooking as their amylase enzymes convert starches into sugars.
- True Yams (Dioscorea genus): These are tuberous stems related to lilies, not morning glories. True yams have a rough, thick, bark-like skin and starchy flesh that can be white, purple, or yellow. Their flavor is earthy and starchy, similar to a regular potato, and not particularly sweet. They require peeling and are common in West African, Caribbean, and Asian cuisines.
The Sweetest "Yams" Are Often Sweet Potatoes
Given that the sweetest options are almost always sweet potatoes, here is a breakdown of the varieties most people look for when searching for the sweetest "yam."
Japanese Sweet Potato (Satsuma-imo)
Widely regarded as one of the sweetest varieties of sweet potato, the Japanese sweet potato has a reddish-purple skin and a creamy, pale yellow flesh that turns golden when cooked. Its texture is dense and starchy, and its flavor is exceptionally sweet with nutty, chestnut-like undertones. The sweetness becomes more pronounced upon roasting or steaming, as the heat encourages the starch-to-sugar conversion process.
Beauregard Sweet Potato
The most common commercial variety in the U.S., the Beauregard has a reddish-purple skin and a deep orange, juicy flesh. It is known for its high moisture content and rich, sweet flavor, making it perfect for mashing, baking, and incorporating into desserts like pies and casseroles.
Filipino Purple Yam (Ube)
For a truly unique flavor and visual appeal, the Filipino Purple Yam, or Ube (a true yam, Dioscorea alata), offers a sweet, nutty taste and a striking violet color. Popular in Asian cuisine for desserts, its use showcases that some true yams can indeed be sweet, though they are less common in general grocery stores than sweet potatoes.
Comparison of Sweet Potato & Yam Varieties
| Variety | Type | Sweetness | Flavor Notes | Texture | Best For |
|---|---|---|---|---|---|
| Japanese (Satsuma-imo) | Sweet Potato | Very Sweet | Nutty, chestnut-like | Dense, starchy | Roasting, steaming, stuffing |
| Beauregard | Sweet Potato | Very Sweet | Rich, juicy | Moist, creamy | Mashing, baking, pies |
| Ube | True Yam | Sweet | Sweet, nutty | Moist, dense | Desserts, baking |
| Jewel | Sweet Potato | Moderately Sweet | All-purpose sweet | Moist, orange | Casseroles, mashing |
| Hannah | Sweet Potato | Mildly Sweet | Potato-like | Dry, firm | Roasting, fries, soups |
| True African Yam | True Yam | Not Sweet | Starchy, earthy | Dry, starchy | Stews, boiling, frying |
Maximizing Sweetness During Cooking
To get the most out of your naturally sweet sweet potatoes, employ cooking techniques that promote the conversion of starch to sugar. The enzyme responsible for this, amylase, is most active at temperatures between 135°F and 170°F (57°C and 77°C).
- Slow Roasting: Roasting sweet potatoes whole in a low oven (around 300°F) for an extended period, followed by a blast of high heat to caramelize the sugars, is an excellent way to enhance their sweetness.
- Pre-Freezing: For maximum sweetness, Serious Eats suggests freezing whole sweet potatoes solid before slow-roasting them. This draws out excess water and concentrates the flavor, while the gradual reheating maximizes the enzymatic activity. For a step-by-step guide, check out their article on The Best Way to Cook Whole Sweet Potatoes.
- Steaming or Boiling: While these methods are quicker, they don't produce the same level of sweetness and flavor concentration as roasting. The finished potatoes are typically blander in comparison.
Conclusion
When asking "what is the sweetest type of yam?" the answer depends on whether you are talking about true yams or the sweet potatoes most Americans refer to as yams. For those seeking the classic, sweet, and moist experience, varieties like the Japanese sweet potato and the Beauregard are top contenders. If you're lucky enough to find true yams, like the Filipino Ube, you'll experience a sweet and nutty flavor distinct from the usual grocery store find. Understanding the difference and choosing the right variety for your recipe can make all the difference in achieving the desired sweetness and texture.
