Purple potatoes aren’t a single variety. They range from potatoes that are purple only on the outside to ones that are purple all the way through, and some of the “purple potatoes” in stores are really purple sweet potatoes, a separate plant with a different taste and texture. Knowing which kind you’re holding tells you how it will cook and how much color it will keep.
The Main Types by Skin and Flesh Color
The purple color comes from anthocyanins, the same family of pigments that colors blueberries and red cabbage. Potato varieties differ in which of these pigments they carry, which gives shades from red-violet to deep blue-purple.1Food Science and Technology Research. Anthocyanins from Skins and Fleshes of Potato Varieties
- Purple skin, white or yellow flesh: looks like a regular potato once peeled.
- Bicolored or marbled: purple skin with flesh streaked or ringed in purple, as in Purple Viking types.
- Solid purple: purple skin and flesh throughout, as in Purple Majesty, Blue Congo, and Vitelotte.
Purple skin alone tells you little about the inside. If the market allows it, a small nick through the skin with a thumbnail, or a cut sample, shows the flesh color. When you can’t check, a bag label or a grower’s sign naming the variety is the next best clue.
Once you’re home, solid purple types stay vividly colored when sliced raw, so a cut one looks like a violet disc. Skin-only types lose nearly all their purple when peeled. If color is the point of the dish, leave the skin on or choose a solid type.
Names don’t line up neatly. Heirloom names such as Vitelotte, Congo, and Négresse often describe potatoes that look very similar, so two different names may mean nearly the same dark, solid purple potato. Words like “blue” and “purple” are used loosely. Even within a named variety, growing conditions can make a crop deeper or paler from one season or farm to the next.
Purple Sweet Potatoes Are a Different Plant
Sweet potatoes belong to the morning glory family, while regular potatoes are nightshades. Among sweet potatoes, only the purple-fleshed kinds contain purple pigments, while orange ones are rich in beta-carotene instead.2PubMed Central. Comparative analysis of phytochemicals and polar metabolites from colored sweet potato (Ipomoea batatas L.) tubers
At the store, many purple sweet potatoes, such as Okinawan types, have tan or cream skin that hides deep purple flesh, so they can look like ordinary pale sweet potatoes until cut. Others, such as Stokes Purple, are purple in both skin and flesh, which is where they’re most easily confused with true purple potatoes. Purple potatoes tend to be rounder or finger-shaped with thin skin, while sweet potatoes are usually longer and tapered. The label is the surest clue: a sign saying “sweet potato” means the other plant, whatever its color.
In the kitchen the difference is obvious. Purple sweet potatoes taste noticeably sweet and turn dense and creamy when cooked, a very different result from the fluffy, earthy bite of a purple potato. They roast and mash well and pair with sweet or savory spices, such as cinnamon or chili. They can’t replace potatoes one-for-one in potato salad or any dish that depends on firm, savory cubes, because they soften and sweeten the dish.
How Purple Potatoes Cook and Taste
Cooks sort potatoes as mealy (fluffy and starchy) or waxy (firm, holding their shape). Most purple potatoes are on the mealy side.3The Chopping Block. Understanding Potatoes They make good mashes and bakes but can crumble when boiled for potato salad.
That plays out differently by type. Solid purple fingerlings are small enough to roast whole, and their skins crisp while the flesh stays creamy. Marbled types look attractive halved and tossed into salads, where the pattern shows on the cut face. Mashing turns the flesh anywhere from lavender to deep violet depending on the variety, which surprises people expecting a white mash. Chips and fries show off the color dramatically, though fried versions add fat that the plain potato doesn’t have.
In taste tests, people rated purple potatoes as flavorful as white and yellow ones.4Scientific Research Publishing (Food and Nutrition Sciences). Sensory Evaluation of Pigmented Flesh Potatoes (Solanum tuberosum L.) They liked the look and smell less, though.5Scientific Research Publishing (Food and Nutrition Sciences). Sensory Evaluation of Pigmented Flesh Potatoes (Solanum tuberosum L.)
A little acid, such as vinegar or lemon juice in the cooking water or dressing, helps keep purple bright. Baking soda or very hard water makes the cooking liquid more alkaline, which can shift the color toward blue or green. Leftovers may darken slightly overnight in the refrigerator, which is harmless and affects looks more than taste.
Are Purple Potatoes Healthier
Purple potatoes had about twice the polyphenols, a type of antioxidant compound, of white potatoes.6PubMed Central. Antioxidant Contents and Antioxidant Activities of White and Colored Potatoes (Solanum tuberosum L.) Colored-flesh potatoes had several times more of these compounds than yellow or white ones.7PubMed Central. Phenolic Compounds and Antioxidant Activities of Potato Cultivars with White, Yellow, Red and Purple Flesh That is a real difference, but it describes what’s in the food, not proven health results in the person eating it.
Purple Viking also had more potassium than an Idaho potato, about 448 versus 295 mg per 100 grams.8PubMed. Changes in potassium content of different potato varieties after cooking Potassium is useful for most people, so that’s a plus. But failing kidneys can’t clear potassium well, so people told to limit it should check with their care team and not treat purple as a lighter swap.
On blood pressure, eating six to eight small microwaved purple potatoes twice a day for four weeks lowered blood pressure about 5 points in a small group with high blood pressure.9PubMed. High-antioxidant potatoes: acute in vivo antioxidant source and hypotensive agent in humans after supplementation to hypertensive subjects But the drop was modest, and the amounts were far more than most people eat. In healthy adults eating 200 grams daily for two weeks, blood pressure did not change, though arteries became slightly less stiff.10PubMed Central. Antioxidant Rich Potato Improves Arterial Stiffness in Healthy Adults
On blood sugar, purple potato extract eaten with a meal lowered the blood sugar rise in healthy men.11PubMed. Anthocyanin-rich extract from purple potatoes decreases postprandial glycemic response and affects inflammation markers in healthy men The pigments may slow a gut enzyme that breaks down starch.12PubMed. The glycemic index of pigmented potatoes is related to their polyphenol content These were small, short studies, so a purple potato remains a starchy food.
Does Cooking Destroy the Purple Pigments
Cooking cut pigment levels in purple potatoes by anywhere from about 7% to 83% depending on method.13PubMed. Domestic cooking methods affect the phytochemical composition and antioxidant activity of purple-fleshed potatoes Boiling, microwaving, and baking all lowered these compounds.14LWT. Effects of cooking methods on polyphenols, pigments and antioxidant activity in potato tubers Steaming, however, better preserved antioxidant activity than plain boiling.15PubMed Central. Effect of Cooking Methods on Bioactivity of Polyphenols in Purple Potatoes Gentler, shorter cooking keeps more.
Several habits help. Leave the skins on, because pigment is concentrated there and peeling before cooking removes part of it. Stop cooking when a fork slides in easily, since cooking until mushy gives the pigments more time to break down. If you boil, some pigment leaches into the water, so using that purple water in soup or a sauce puts it back on the plate.
Storing Purple Potatoes
Purple potatoes stored around 4°C (refrigerator-cold) often grew more purple over time than those at 10°C.16mountainscholar.org. Influence of storage temperature and time in storage on pigment content of potato (Solanum tuberosum L.) Cold turns some starch to sugar, which the potato can convert into pigment.17Journal of the Science of Food and Agriculture. Changes in anthocyanin, flavonoid and phenolic acid concentrations during development and storage of coloured potato (Solanum tuberosum L) tubers The effect varied, though, with one variety gaining 18% pigment and another losing 34%.18Food Chemistry. Impact of selected factors – Cultivar, storage, cooking and baking on the content of anthocyanins in coloured-flesh potatoes Cold-stored potatoes also taste sweeter and may brown more when fried.
For everyday storage, keep potatoes in a cool, dark place such as a cupboard or basement shelf, away from onions, which can speed spoilage. Light causes greening, which signals a bitter compound you don’t want to eat, so a paper bag or closed bin helps. Plan to use them within a few weeks, since quality and firmness decline at home temperatures. Small green spots or sprouts can be cut away, but throw out potatoes that are extensively green, soft, or heavily sprouted, and don’t try to rescue badly affected ones by cutting away the bad parts.