Turn Your Sourdough Purple! This Ingredient Is A Perfect Natural Dye

Sourdough bread-making peaked during the 2020 lockdown, and people have been obsessed with it ever since. In fact, sourdough remains one of the fastest-growing trends in baking and is among the most common types of bread you'll find at the supermarket. But apart from the traditional sourdough you usually see on bakery shelves, there's a new colorful loaf that has been getting attention lately: purple sweet potato sourdough. Purple sweet potatoes, also known as Okinawan sweet potatoes, are rich in anthocyanins, healthy antioxidant compounds responsible for their distinct purple hue. The potatoes blend smoothly into bread dough without affecting its hydration or structure, and the anthocyanins can even extend the bread's shelf life.

To get a better idea of what makes purple sweet potato so good for sourdough, Chowhound spoke with Audrey Santos, sous chef and pastry chef at Maricel's Kitchen, a Filipino restaurant located in East Brunswick, New Jersey. "Purple sweet potato gives such a vibrant, rich color, and it stays that way even after baking," Santos said. "It's reliable and consistent, which is what I want in a working kitchen."

If you're looking to turn your sourdough violet, purple sweet potato isn't your only option. "Blueberries, blackberries, black raspberries, red cabbage, and ube can all give you beautiful purple tones," Audrey Santos explained. "They each behave differently: berries soften the color and add more liquid, cabbage is surprisingly vibrant but can affect flavor, and ube is very similar to purple sweet potato but can vary depending on the variety."

Ube has been popular for centuries in Southeast Asian cuisine, but it gained traction in the U.S. in 2016, when the Brooklyn-based Filipino restaurant Manila Social Club began selling its now-famous ube donuts. This starchy, delicate yam is native to the Philippines and boasts a sweet, earthy, vanilla-like flavor. Black rice is another ingredient often used to color sourdough. It also gives the bread an incredibly soft and tender texture thanks to its natural moisture and stickiness.

When asked whether natural purples fade during baking, Santos explained that while some do, both purple sweet potatoes and ube can retain their color remarkably well. "You may see a darker crust, but the crumb stays vibrant," Santos said. "Berry colors fade more easily, especially if the dough gets too acidic during fermentation, so controlling that timing matters."

When it comes to preparing purple sweet potato for sourdough, Audrey Santos revealed that steaming is the best method to preserve its intense color. The potato's pigments are water-soluble, meaning they can easily leach out into the water if boiled. "Add it early during mixing so it becomes part of the dough structure," Santos elaborated. "And remember to pull back on the water a bit since the puree adds moisture."

In terms of fruits, she prefers simmering them until the water evaporates to concentrate their flavor before straining out the skins. This useful technique allows the color to come through in the dough without interfering with the gluten or negatively affecting its texture. If you have some berries that are about to go bad, adding them to your next sourdough loaf is a great way to use up overripe fruit instead of tossing it.

It's important to use the ingredients properly as each one has an effect on the finished product. "Purple sweet potato and ube make the crumb softer and give a light sweetness," Santos explained. Berries can add some fruity flavor and a bit of sugar, while red cabbage can give the bread a sweet, tangy flavor that pairs well with certain spices. When used correctly, each of these ingredients can create a beautiful, tasty loaf.