You’ve washed your sweet potatoes and you’re ready to start cutting them up to boil for mashed potatoes. As you start chopping away, you start to notice a white ooze come out of these orange root vegetables. You may squirm or gasp because this hasn’t happened before and you’re wondering is this a bad thing?
It turns out that the white substance is normal and has a name–it’s sap.
What Is Sweet Potato Sap?
A sweet potato that has sap is a good sign–it means it’s fresh. “The sap is a naturally occurring mixture of sugar, starch, and water,” says Ann Ziata, chef at the Institute of Culinary Education. As your knife slices through the sweet potato, the vegetable’s cell walls break and that’s when, according to Tiffany Sage Swan, food scientist and professional chef, “the starches, sugars, and waters in the cells start to ooze out of the flesh of the sweet potato.”
Wondering why sap is white instead of bright orange? The color of the sap is related to the starch content. “Sweet potatoes are high in starch and sugar, which gives the sap its white color and sweet taste,” says Ziata.
When you consider that root vegetables are predominantly water, it makes sense that moisture may come out. “A raw sweet potato is about 77% water, and the fresher it is, the juicier it will be,” says Ziata. The sap is nature’s way of letting you know that the sweet potato is recently harvested and is good to eat. “The ooze is an indication that the sweet potato is fresh and still contains plenty of moisture,” says Swan.
If you often buy from local growers at the farmers market or purchase organic sweet potatoes at the supermarket, you’re more likely to see sap when you slice into one. “Organically grown sweet potatoes are also more likely to release sap than conventionally grown ones,” says Ziata.
Have you ever decided to only use half of a sweet potato for your recipe and planned to store the rest for another dish? You probably saw the sap come out and while attending to other kitchen tasks before storing it, you may have wondered why there is now a spot on the tuber? Nature has its own mechanism to ensure survival and protection, even when it comes to vegetables. “Once the ooze has escaped, the water evaporates and leaves a resinous spot behind that helps retain the moisture and nutrients of the sweet potato so it can continue to grow, or preserve itself before cooking,” says Swan.
What If My Sweet Potato Doesn’t Have Sap?
Aside from organic sweet potatoes being more likely to contain sap than conventionally grown ones, a lack of sap can also be an indicator that the vegetable has been out of the ground for a while. Typically, the older the sweet tuber is, the less likely it will contain sap. “If it is too dry, the starches and sugars are not able to escape because there is not enough water to carry them,” says Swan.
A milky substance on your sliced sweet potato doesn't mean that your spud is rotten or spoiled. The ooze is actually referred to as "sap." It is made up of sugar and starch combined with the moisture found in the vegetable, and it escapes from the damage made by the knife.
Sometimes called eyes, these frilly growths can look worrisome but are entirely natural. Sprouted potatoes are safe to eat, too; just remove the eyes and check the rest of the potatoes for freshness.
“A raw sweet potato is about 77% water, and the fresher it is, the juicier it will be,” says Ziata. The sap is nature's way of letting you know that the sweet potato is recently harvested and is good to eat. “The ooze is an indication that the sweet potato is fresh and still contains plenty of moisture,” says Swan.
Starch is a complex carbohydrate that's abundant in our sweet potato flesh. When we're heated, the starch granules absorb water and swell up, releasing a sticky substance known as amylopectin. Think of amylopectin as our sweet potato glue—it's what gives us that creamy, velvety texture when mashed or baked.
How to tell if sweet potatoes have gone bad. If your sweet potato is soft in spots, smells rotten, or oozes a mysterious liquid, that potato should be discarded. Another sign that sweet potatoes have taken a turn for the worse is if they start growing stalky purplish sprouts.
Sweet potatoes in storage are commonly infected with the bread mold fungus, which causes a watery soft rot of part or all of the tuber. The fungus may be seen as a fluffy, white growth, with black dots supported on threads.
“The bacterium is 'soft rotting' or pectolytic, meaning it breaks down plant cell walls,” said plant pathologist Amanda Gevens at the University of Wisconsin-Madison. “[The microbes] can be found in soils and may be subsequently brought into potato storages on tubers during the harvest process.”
Absolutely!Sprouted sweet potatoes can either be fried, boiled, baked or tossed into a stir fry. With tender sprouts, you can prepare an assortment of recipes that your family will surely enjoy. Just remove the shoot, and you can proceed in preparing your delicious sprouts.
If the green tint on your taters is light and mostly skin-deep, peel them well to remove the green parts and go forth. But if they're starting to look like post-transformation Fiona, it's time to pitch 'em. Same goes for potatoes that have gone mushy or wrinkly—those are tell-tale signs of spoilage.
Sweet potatoes with orange flesh are richest in beta-carotene. Sweet potatoes with purple flesh are richer in anthocyanins. Beta-carotene and anthocyanins are naturally occurring plant “phyto” chemicals that give vegetables their bright colors.
White sweet potatoes won't have as much beta carotene content, but they're still a good choice nutritionally. Visually, the white sweet potato can better replicate the appearance of classic potatoes.
The ooze is actually referred to as "sap." It is made up of sugar and starch combined with the moisture found in the vegetable, and it escapes out of the damage made from the knife. The sap really equals the sweetness. If it's pouring out of your potato, that means it's a sweet and delicious vegetable.
Sweet potatoes stored at temperatures above 60 degrees Fahrenheit will shrivel and become dry and stringy. Sweet potatoes may develop an off-flavor and the flesh may become discolored when stored at temperatures below 55 degrees Fahrenheit.
White mold of potatoes is caused by the fungus Sclerotinia sclerotiorum (Lib.) de Bary. (See life cycle chart). This fungus has a very wide host range. The fungus produces white and fluffy mycelium and also produces hard, black, irregularly shaped sclerotia.
When potatoes start to sprout, they grow “eyes,” which tend to start off as small reddish-white bumps and can quickly turn into centimeters-long growths. But can you actually eat a sprouted potato? In short, yes, as long as you cut the sprouts away.
One potato tuber will often produce more than a handful of sprouts or slips. These slips are removed from the original tuber by a careful twist, or, by keeping them attached to the tuber and slicing them off. Each of those slips can grow into a plant that can produce about 6 sweet potatoes.
Discoloration Fresh sweet potatoes should have a uniform color without any dark spots or discoloration. If you see brown or black spots on the sweet potato's skin or inside the sweet potato, this is a sign of spoilage and possible mold growth.
Introduction: My name is Corie Satterfield, I am a fancy, perfect, spotless, quaint, fantastic, funny, lucky person who loves writing and wants to share my knowledge and understanding with you.
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