Short publication providing information on nutritive value and recipes for sweet potato tubers and leaves

Bisone, Laura E.

Maretzki, Audrey N.

ScholarSpace at University of Hawai'i at Manoa

HAWAII COOPERATIVE EXTENSION SERVICEHawaii Institute of Tropical Agriculture and Human ResourcesUniversity of Hawaii at ManoaCOMMODITY FACT SHEET SP-1 (A)VEGETABLESWEET POTATOLaura E. Bisone and Audrey N. MaretzkiDepartment of Food Science and Human NutritionPhoto by Gary MorlharaBotanical name: Ipomoea batatasHawaiian: 'ualaSamoan: umalaFilipino: kamoteDescriptionThere are many vanetles of sweet potato. Theydiffer in flesh texture and color, skin color, andleaf shape. Sweet potatoes may be coarse and dryor smooth and moist. The flesh is white, lavender,or orange. The skin is white, tan, orange, red, orpurple. Sweet potato leaves range from heart-shaped to five-lobed. A few varieties grow asbushes, but most are vines.The moist, orange-fleshed types are often calledyams. The true yam, however, belongs to a dif-ferent family.Both the leaves and the root of the sweet potato canbe eaten. Sweet potato leaves are generally not1available at supermarkets but can be found at openmarkets, swap meets, and some small ethnicmarkets.If you wish to grow your own sweet potatoes, askyour local county extension agent for information.Nutrition InformationAll sweet potatoes are not equally nutritious. Insome varieties, however, both the roots and theleaves are good sources of vitamins A and C. Onesmall baked sweet potato of the golden-fleshvariety supplies between 600 and 10,000 Inter-national Units of carotene, which the human bodyconverts to vitamin A. The darker the flesh, thehigher the carotene content.An average, unseasoned sweet potato weighing100 grams provides 141 calories. It also providesmore than one and one-half times an adult'srecommended dietary allowance (RDA) for vita-min A and more than one-third of the adult allow-ance for vitamin C. Thiamin (vitaminB 1 ) andiron are also provided in significant but smalleramounts (see Fig. 1).Because the leaves are much lower in carbohydratethan is the root, a 5/8 cup serving of boiled sweetpotato leaves provides only 32 calories. It alsoprovides more than one-third of an adult's RDAfor vitamin A and a smaller but still significantamount of protein, riboflavin (vitamin B2), andphosphorus (see Fig. 2). The raw leaves containlarger amounts of some nutrients than do thecooked leaves. When cooking sweet potato leaves,you can prevent the loss of vitamins and mineralsby saving the cooking water and using it in soupsor stews.Sweet Potato Tuber (baked)100 grams =4"x 2"141 caloriesSweet Potato Leaves (boiled)100 grams =5/8 cup32 calories__Nu_tri_en_t~ 9Vitamin AVitamin CThiaminIron0/0 Recommended Doily Allowance25 50 75 100 12~ 150 175162% I NutrientProteinVitamin ARiboflavinPhosphorus0/0 Recommended Daily Allowance25 50 75 100 125! ! I I I150I-igure 1. Major nutrients in 100 grams baked sweet potato tuber,given as percentage of U.S. RDA.PreservationFresh sweet potatoes don't keep well. If you have alot, you may want to preserve them by canning,freezing, or drying.One bushel (55 pounds) of sweet potatoes willprovi~e 18 to 22 quarts of canned potato and 34to 38 pints of frozen potato. Sweet potatoes shouldbe cured before processing to ensure good flavor.Sweet potatoes are a low-acid food and should notbe canned unless pressure canning equipment isavailable. Consult a textbook or guide to canninglow-acid foods.To freeze sweet potatoes, follow these steps:1. Wash the potatoes and cook them until almosttender.2. Peel after cooking.3. To prevent the darkening that occurs in freezing,dip the sweet potato into a solution of ~ cupFigure 2. Major nutrients in 100 grams boDed sweet potato leaves,given as percentage of U.S. RnA.lemon juice or 1 tablespoon citric acid in 1 quartof water. Two teaspoons of orange or lemonjuice may be added to each quart of mashedsweet potatoes.4. Pack sweet potatoes, leaving ~ ,inch headroom.5. If desired, a light sugar syrup (¥2 to 3A cupsugar dissolved in 4 cups water) may be added towhole or sliced sweet potatoes before freezing.6. Seal and freeze.Sweet potatoes may also be dried. Cook themthoroughly, then slice into 1/8-inch slices or strips.Consult a guide on drying techniques to find outwhich method is best for the resources that youhave. After drying, sweet potatoes should be con-ditioned and pasteurized. Condition them bystoring the dried vegetables in a covered non-aluminum container for 10 days, stirring themonce or twice a day. Pasteurize by heating thedried sweet potato for 10 minutes at 175 0 F.Nutrients in 100 g sweet potato leaves and 100 g sweet potato tuberNutrientCaloriesProteinCalciumPhosphorusIronVitamin AThiamin (vit. B1)Riboflavin (vit. B2)NiacinAscorbic acid (vit. C)BoDed sweet potato leaves323g24mg60mg.6mg1898 IV.07 mg.18 mg.7 mg1 mg2Baked sweet potato1412g40mg.9mg8100 IV.09 mg.06 mg.6mg22mgRecipesRoasting is the most common way to prepare sweetpotatoes. First rub the potato with oil, then prickit with a fork, and bake at 350°F. for about 1 hour,or until tender.Koele Palao (Crustless Sweet Potato Pt"e)4 c. raw sweet potatoes1 t. salt3 T. sugar2 c. coconut cream2 T. margarine~ c. flaked coconut1. Boil unpeeled sweet potatoes until tender.2. Peel, then mash until smooth, adding salt, sugar,and coconut cream.3. Turn into a 9-inch greased pie plate.4. Bake at 4000 F for 20 to 25 minutes, or untilvery delicately browned.5. Melt margarine in a skillet and lightly brown thecoconut.6. Sprinkle browned coconut over pie. Serve hot orcold. May be served as a side dish or dessert.Refrigerate unused portion. Yield 6-8 servings.Korean-Style Sweet Potato Leaves1 T. sesame oilIA t. cayenne pepper2 T. fresh grated gingerIA t. salt2Y2 T. lemon juice1 T. honey1 lb. sweet potato leaves and stems, cut into bite-sized pieces1 T. roasted sesame seeds1. Combine the first four ingredients and quicklysaute them in a wok.2. Add lemon juice, honey, and sweet potatostems; stir-fry, until the stems are almost tender.3. Add leaves and stir-fry until they are slightlywilted.4. Serve hot with a sprinkling of toasted sesameseeds. Yield: 6 servings.Other UsesIndustrially, sweet potatoes have been used in themanufacture of textiles, cosmetics, paper, and ad-hesives. A permanent dye can be made from somesweet potato skins.The leaves and stems are given to animals as food.Sweet potato leaves are often fed to tilapia fish.The Maoris of New Zealand boiled the entireplant and used the remaining liquid to treat acneand other skin eruptions.For More InformationAbout Fz"lz"pino Foods. 1978. Home EconomicsCircular 347, CTAHR. 6 pp.Hertzberg, R., B. Vaughan, and J. Greene. 1973.Putting Food By. Brattleboro, VT: The StephenGreene Press.Sweet Potatoes. 1978. Home Garden VegetableSeries 12,CTAHR. 2 pp.ReferencesFood Composition Table for Use z"n East Asz"a.1972. FAO, DHEW. National Institute ofArthritis, Metabolism, and Digestive Diseases.Nutrz"tz"ve Value ofFoods. 1971. Home imd GardenBulletin No. 72, USDA.Patton, Stacy. 1979. The Feasz"bz"lz"ty of- Dz"etQualz"ty Improvement Using Tropz"cal Vegetables(Master's thesis).United States Recommended Daily Allowances(US-RDA). 1974. DHEW Publication No.(FDA) 74-2010.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agricul-ture. Noel P. Kefford, Director of the Institute and Dean of the College, Cooperative Extension Service, College of Tropical Agriculture andHuman Resources, University of Hawaii at Manoa, Honolulu, Hawaii 96822. An Equal Opportunity Employer providing programs and servicesto citizens of Hawaii without regard to race, color, national origin or sex. 07/82 (5M)

Sweet Potato

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Sweet Potato

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