Sweet potatoes are a delicious and nutritious vegetable that can be prepared in many ways. However, getting sweet potato fries or chips nice and crispy can be a challenge compared to regular potatoes. There are a few reasons why it’s difficult to get that satisfying crunch when cooking sweet potatoes.
High Moisture Content
One of the main reasons sweet potatoes don’t get as crispy is their naturally higher moisture content. On average, sweet potatoes contain about 75% water, whereas regular russet potatoes are only around 80% water. This extra moisture means the sweet potato slices won’t dehydrate as efficiently when cooking, inhibiting that crispy texture.
When frying or baking sweet potato fries, the excess moisture will steam the fries from the inside rather than allowing the surface to get ultra crisp. Some of that moisture needs evaporating first before the crisping can begin.
Higher Sugar Content
Another factor is the higher sugar content in sweet potatoes compared to regular potatoes. Sweet potatoes get their sweet flavor from higher levels of sugars like sucrose, glucose and fructose. A 100 gram serving of baked sweet potato contains around 7 grams of sugar, whereas white potatoes contain just 1 gram.
These sugars assist with the Maillard reaction, which is the browning and caramelization process that produces crispy textures. However, too much sugar can cause burning or over-browning before the interior cooks through. The abundant sugars in sweet potatoes make it tricky to time that perfect crispness.
Less Starch
Regular potatoes get ultra crispy partially thanks to their high starch content. Potatoes contain around 15-20% starch, composed of amylose and amylopectin. These starches help form a crispy outer layer when potatoes are fried, while keeping the interior moist and fluffy.
Comparatively, sweet potatoes only contain around 5-10% starch. With less starch available to create that crispy shell, it’s more difficult for the exterior of sweet potatoes to get truly crunchy. The lower starch content also means the interior doesn’t fluff up as nicely either.
Dense Cell Structure
Sweet potatoes have a denser, firmer flesh and cell structure compared to regular potatoes. While russet potatoes are light and fluffy when cooked, sweet potatoes retain a dense, almost meaty texture. This compact cell structure doesn’t lend itself well to getting super crispy and crunchy during cooking.
Preventing Excess Softness
While it’s tricky getting sweet potatoes ultra crispy, you can prevent them from ending up too soft and mushy by:
- Cutting sweet potatoes no thicker than 1⁄4 inch for fries or chips.
- Rinsing cut sweet potatoes in cold water to remove excess starch.
- Drying the sweet potato fries thoroughly before cooking.
- Frying between 325-375°F for the best texture.
Following these tips can help maximize the crispness potential of sweet potato fries or chips. Though they likely won’t get as crunchy as deep-fried russets, you can still achieve a pleasant crispy exterior.
Methods to Increase Crispness
If you’re determined to get those sweet potato fries or chips as crispy as possible, here are some methods to try:
Double Fry
Double frying is a technique restaurants use to get ultra crispy fries. The fries are fried once at a lower oil temperature, then again at a higher temperature. This helps remove moisture and thoroughly cooks the interior before crisping the exterior. Cut sweet potatoes into fries, fry at 325°F for 2-3 minutes, let cool, then fry again at 375°F until crispy.
Bake Then Fry
Baking the sweet potatoes first can help drive off some moisture before frying. Cut the sweet potatoes into fries or chips, toss with a little oil, and bake at 425°F for 15 minutes. Then fry at 350-375°F until crispy.
Use a Dehydrator
A dehydrator removes moisture slowly over low, sustained heat. Dehydrate sweet potato fries or chips for 2-3 hours until the pieces look dried out but not browned. Then you can finish by air frying or baking briefly to add crispy texture.
Add Baking Soda
Tossing the sweet potato fries in baking soda before cooking can help increase crisping. The alkaline baking soda raises the pH on the surface of the fries, accelerating browning through the Maillard reaction. Just add 1 teaspoon baking soda per 1 pound of sweet potatoes and toss to coat.
Use Crisping Agents
Certain starchy ingredients can encourage crisping when added to the sweet potatoes. Toss fries or chips in a little cornstarch, arrowroot starch or tapioca starch before frying or baking. Rice flour or panko breadcrumbs also provide crispy results.
The Best Cooking Methods for Crispy Sweet Potatoes
While sweet potatoes won’t get quite as crispy as regular potatoes, you can still achieve a satisfying level of crispness using certain cooking methods.
Air Frying
Air fryers promote crisping using extremely hot, concentrated air. The high heat of an air fryer will caramelize the exterior of the sweet potatoes while cooking the inside. Air fry sweet potato fries at 400°F, shaking halfway, for 15-20 minutes.
Deep Frying
A deep fryer allows you to fine tune the oil temperature and cook the sweet potatoes evenly for the crispiest exterior. Fry at 350-375°F for 2-3 minutes for crispy sweet potato french fries with tender insides.
Baking
The dry heat of an oven draws moisture out of the sweet potatoes, though they may not get quite as crispy. Bake sweet potato fries or chips at 425°F for 25-30 minutes, tossing halfway through.
| Cooking Method | Temperature | Cook Time |
|---|---|---|
| Air Fryer | 400°F | 15-20 minutes |
| Deep Fryer | 350-375°F | 2-3 minutes |
| Baking | 425°F | 25-30 minutes |
Choosing the Best Sweet Potato Variety
Certain varieties of sweet potatoes tend to get crisper than others. The best ones to use are:
Japanese Sweet Potatoes
Japanese sweet potatoes have purple skin and drier, white flesh. Their texture and starch content lend better to crisping than the moister, orange-fleshed sweet potatoes.
Jewel Yams
Jewel yams are a variety of sweet potato with copper skin and bright orange flesh. Their flesh is less dense and fibrous compared to other sweet potatoes.
Garnet Yams
Garnet yams have reddish-orange skin with matching flesh. They have a similar moisture content to regular potatoes, helping create a crisper exterior when cooked.
| Sweet Potato Variety | Description |
|---|---|
| Japanese | Purple skin, white flesh. Low moisture. |
| Jewel Yam | Copper skin, orange flesh. Less dense. |
| Garnet Yam | Reddish-orange skin and flesh. Lower moisture. |
Selecting a drier, less moist sweet potato variety can help maximize the crisping potential when frying or baking.
Tips for Crispy Baked Sweet Potatoes
It’s not just sweet potato fries and chips that have crisping challenges. Getting baked whole sweet potatoes crispy on the outside while cooking through can also be tricky. Here are some tips:
- Prick holes in the sweet potatoes with a fork so steam can escape.
- Rub a little oil on the skins to help conduct heat.
- Bake at 400°F for 40-60 minutes until easily pierced with a fork.
- Finish under the broiler for 3-5 minutes to crisp and caramelize the skins.
monitoring the sweet potatoes closely and finishing with high heat under the broiler will help achieve a crispy skin on baked whole sweet potatoes.
Using a Microwave First
Another option is to microwave the whole sweet potatoes first before baking. This partially cooks the interior and removes some moisture.
To do this:
- Prick sweet potatoes with a fork and microwave on high for 4-5 minutes, flipping once.
- Let cool slightly, rub with oil, then bake at 400°F for 20-30 minutes until crisp.
The microwave jump starts the cooking process so the baked sweet potatoes spend less time steaming and more time crisping up.
Other Serving Ideas Without Crisping
Rather than struggling to get sweet potatoes crispy, you can also serve them in ways that highlight their natural texture:
- Mash them into sweet potato casseroles or souffles.
- Roast cubes of sweet potato tossed in oil and spices.
- Puree cooked sweet potatoes into creamy soups.
- Bake into sweet potato pies, breads or muffins.
Embracing the soft, smooth side of sweet potatoes can be just as satisfying and eliminates the challenge of crisping them up.
Conclusion
Perfectly crispy sweet potato fries may be difficult to achieve, but not impossible with the right techniques. Key factors like their moisture content, sugar levels, and dense cell structure make sweet potatoes harder to crisp up compared to regular russets. Using methods like double frying, dehydrating, and choosing lower moisture varieties can set you up for crisper results. Though they likely won’t ever get as crunchy as deep-fried regular fries, you can still enjoy lightly crispy, tender-inside baked or air fried sweet potato fries with the right prep and cooking methods. And for times you’d rather not deal with the crisping issue, roasted, mashed or pureed sweet potatoes are delicious just as they are.