One of the sweetest and most popular vegetables is the sweet potato. Although their wonderful flavor and nutritional value can be enjoyed year-round, until recently sweet potatoes were sometimes only seen on the dinner table around Thanksgiving. Sweet potatoes are native to Mexico, Central and South America, as well as the West Indies, but North Carolina ranks first in the United States in the production of this very nutritious vegetable. The sweet potato has been confused with the yam; however, the nutritional value of the sweet potato versus the yam is quite different. Sweet potatoes contain high levels of beta carotene. Yams have very little. Although sweet potato recipe possibilities are almost limitless, dried sweet potatoes are now taking center stage as a healthy snack. The nutritional value in the sweet potato in its dried state is considerable. While there has been a difference of opinion regarding the nutritional value of dried vegetables verses fresh, some nutritionists have now decided that they prefer the value of the vegetable in its dried state.
Nutritional Value
Sweet potatoes are naturally good sources of vitamins A, C, B2 (Riboflavin) and E, as well as of dietary fiber, potassium and iron. They are are low in fat and cholesterol and have several other nutritional and dietary benefits including:
• Being high in antioxidants and many other vitamins and minerals
• Rich in potassium
• A great source of dietary fiber
• Soothing to the stomach and intestines
• Among the most nutritious vegetables
• A low glycemic index
• No preservatives, artificial colors or sweeteners
• Great for humans and dogs with allergies or sensitive stomachs
• Highly digestible energy source
What the Experts Think
According to Dr. Sakina Bajowala, M.D., allergist, immunologist and nutritionist, of Chicago, Illinois, there are nutritional differences between dried and fresh vegetables and fruits. The general marketing consensus is that fresh vegetables are visually more appealing than dried, thereby earning more display space and adding color to the produce sections of stores and farmers' markets. But nutritionist and author Sara Le Bas prefers the dried produce, primarily because it is convenient and a time saver. When the sweet potato is created as a dried snack it does not have to be washed, prepared or peeled, thus making it easier to serve, especially to children. Oftentimes, vegetables and fruits are steamed or boiled briefly before they are dried, to help speed up the drying process and to kill microorganisms. This preserves thiamine and carotene, but it causes a loss of vitamin C. Exposure to oxygen and light during the drying process can degrade nutrients even further. Therefore the nutritional losses due to the drying process must be considered.
Studies by the Department of Food Science at Louisiana State University have revealed that sweet potatoes are an excellent source of lutein, which helps keep the eyes safe from oxidative stress and decreases the risk for eye disease, such as age-related macular degeneration (AMD).
If you are prone to midnight cravings of sweets, dried sweet potato snacks are available in several packaging sizes. This delicious snack can help satisfy cravings while still giving you nutritional value and not doing as much damage to your calorie intake as traditional sweets. Both dried and fresh sweet potatoes can play a role in helping to satisfy your sweet tooth. Including them as a snack preference can help you to combat obesity, and the dried varieties make it easier to get your four vegetable nutrition servings each day.
Considerations
Although the convenience, storage and selected nutritional values are apparent, the process of drying the sweet potato with high heat can reduce the effective level of protein that your body is able to obtain. The protein is still there but not as easily absorbed. The water content of fresh vegetables helps to make your stomach full faster, enabling you to consume fewer calories than with the dried vegetable, while getting the same nutrition.
While dried sweet potatoes and other vegetables are more portable and less perishable, you may ultimately consume more calories from them. Fresh sweet potatoes are naturally rich in fiber, potassium, folate and vitamins C and A. While dried sweet potatoes have numerous health benefits as well, the process of drying them can leach some of the nutrients from them. Depending on how they are prepared and dried, the nutritional value can change.
On the positive side, the dried varieties have other benefits. According to the January 2010 CDC Fruit and Vegetable of the Month report, dried sweet potatoes are higher in dietary fiber than their fresh counterparts, due to the increased density caussed by the extraction of water. The high fiber content can be helpful in controlling diabetes, lowering blood cholesterol and helping to relieve constipation. Dried sweet potatoes are also a lot healthier than sugary snacks, and are a quick energy source for athletes.
Air-Dried Sweet Potatoes
In 1992, the Center for Science in the Public Interest compared the nutritional value of air-dried sweet potatoes to other vegetables. Considering fiber content, complex carbohydrates, protein, vitamins A and C, iron and calcium, the air-dried sweet potato ranked highest in nutritional value. The recommended daily serving of dried sweet potatoes is a one-quarter cup (1 oz.) serving or 30 grams, which includes the following daily nutritional values per serving:
Amount/Serving %DV*
Total Fat 0g 0%
Sat. Fat 0g 0%
Trans. Fat 0g 0%
Cholesterol 0mg 0%
Sodium 35mg 1%
Total Carb. 26%
Fiber 2g 9%
Sugars 9g 9%
Protein 1g 9%
Vitamin A 30% • Vitamin C 28% • Calcium 2% • Iron 3%
*Percent Values (DV) are based on a 2,000 calorie diet.
Other Uses
Humans are not the only ones who can take advantage of the dried sweet potato's nutritional value. Pet product companies are creating dried sweet potato snacks for dogs because they are 100 percent natural and completely digestible, unlike rawhide. Products such as Dried Sweet Potato by Canine Caviar are a healthy alternative made from 100 percent natural dried sweet potatoes, giving dogs a fat-free snack that is rich in beta carotene, anti-oxidants, potassium and vitamins A, B6 and C. There are also dog foods that have dried sweet potatoes added instead of other fillers. An added bonus: these products generally contain no added coloring, so they won't stain your carpets.
New Developments in Processing
Sweden's National Food Administration study in 2002 found that commercial drying and frying procedures for sweet potatoes are not healthy and produce the carcinogen PAH (poly-cyclic aromatic hydrocarbon) that is very harmful to the health of the human body. Local studies made by National Taiwan University and Fu-Jen Catholic University, Taiwan, under the support of Taiwan's Health Administration, showed a similar result. Newer innovative techniques using native sweet potatoes along with superheated steam as a way to process, dry and fry the vegetable resulted in a healthier chemical composition, creating a more valuable resource for human and animal consumption.
References
- "Horticultural Commodities Report"; North Carolina Dept. of Agriculture & Consumer Services Markets Division; 2010
- Dr. Sakina Bajowala MD; Allergist-Immunologist; Chicago, IL
- "Nutraceuticals & Functional Foods: General," Session 88; Dept. of Food Science, Louisiana State Univ. Agricultural Center; 2003
- "Sweet Potato Processing and By-Product Utilization"; Asian Vegetable Research & Development Ctr.; F.G. Winarno; 1982
- "Low-Fat Sweet Potato Processing Methods"; FreshContext, LLC Report; 2010
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