Sweet potato roots and leaves are rich in a variety of nutrients required by the human body, such as starch, protein, dietary fiber, lipids, polyphenols, carotenoids, vitamins, and mineral elements such as potassium and calcium, de- pending on different varieties. Based on its excellent nutritional value, research on the extraction and structural, physicochemical, and functional properties of functional components in sweet potato and its by-products from industrial processing have gained widespread attention. Sweet potato has also been processed into flour, flakes, granules, paste, purees, chips, canned products, beverages, and various snack foods. In addition, sweet potato is used as an important supplement for different staple products in the food industry, such as sweet potato steamed breads, baked breads, noodles, and pancakes, etc.

To improve human dietary nutrition, it is important to support research, development, and application of the nutritional and functional components extracted from sweet potato and its by-products, as well as the existing and new snack and staple foods. This will be of great significance in increasing the consumption proportion of sweet potato in people’s daily diet. It is also an inevitable trend for the sustainable development of agricultural production and the improvement of human dietary habits.

Sweet potato (Ipomoea batatas Lam) is an annual herb of the family Convolvulaceae. According to the FAO statistics, as of 2010, there were more than 100 countries planting sweet potato worldwide. The production in Asia is the greatest, accounting for 91.4%; Africa is second, accounting for 5.1%, followed by Latin America, and then Europe. In Asia, the countries with large growing areas are China, Japan, South Korea, Vietnam, and Indonesia.

Since the 16th century (Ming Dynasty), sweet potato has become an important crop in China, with a large planting area that runs from the southern part of Hainan Prov- ince to the northern part of Heilongjiang Province.

Presently, China’s annual sweet potato production is 70.96 million tonnes, accounting for about 68% of the world’s sweet potato production and genetic resources. Starch is the main component of sweet potato, accounting for about 50% to 80% of its dry weight.

Therefore, sweet potato is an ideal starch resource and energy crop. Sweet potato starch plays an important role in the food, chemical, and pharma- cortical industries. Raw materials can produce natural starch and modified starch by primary processing. After the deep processing of natural starch and modified starch, varied starch products can be produced, such as glucose, melogenic amy- lase, sugar substitutes, citric acid, sorbitol, vitamin C, and so on.

In the food industry, sweet potato starch cannot only be used as a processing material, in addition to being used in the manufacturing of vermicelli, jelly, and other consumable products, but also as a food additive, which can be used in food as a thickener, stabilizer, or tissue reinforcing agent to improve foods to retain water, control water flow, and maintain food storage quality The structure, composition, and characteristics of starch are important indices that determine its application.

Sweet Potato: Origin and Production

Botanical characteristics of sweet potatoes The sweet potato (Ipomoea batatas [L.] Lam) is a dicotyledonous plant that belongs to the family Convolvulaceae. It is an herbaceous perennial vine that has white and purple sympetalous flowers, large nutritious storage roots, and alternate heart-shaped or palmate lobed leaves. The large, starchy, sweet-tasting tuberous roots are by far the most important part of the plant. It is a storage root, not a tuber or thickened stem like the potato (Solanum tuberosum). It is also different from yams. They are not related to each other despite a physical and compositional similarity.

The roots of sweet potatoes are long and tapered, with a smooth skin whose color ranges between yellow, orange, red, brown, purple, and beige. Its flesh ranges from beige to white, red, pink, violet, yellow, orange, and purple. The storage root contains a large amount of starch that can be turned into energy in the human body so the root can be consumed as a staple food instead of other staple food crops such as rice, wheat, and corn. The roots, leaves, and stems of sweet potatoes are all edible and nutritious, and thus the cultivation of the sweet potato can play a vital role in ensuring the food security of many developing countries.

Meanwhile the nutritional needs of the people in these countries can also be met by proper consumption of the whole plant. Each 100 g of the fresh root provides an energetic value of 85 kcal, which is greater than that for potatoes but less than for cereals. The root also provides a small amount of protein and relatively higher amounts of vitamins and minerals than cereals. Some varieties of sweet potatoes contain a very high amount of β-carotene that can be converted into vitamin A in the human body, thus the cultivation and consumption of these varieties have been recommended as an applicable approach to prevent the epidemic of vitamin A deficiency that is widespread in many developing countries. The young leaves, shoots, and vine of the plant are a good source of dietary fiber, as well as of many vitamins, minerals, and antioxidant molecules, which makes the sweet potato an excellent vegetable. Nowadays, to fully utilize the value of the plant, the young leaves have been made into teas and powder drinks for human consumption.

Production

Sweet potatoes are now widely cultivated all over the world wherever the plant can survive and the sweet potato has become one of the most important food crops in terms of human consumption. As a high-yield tuberous crop, the plant can be cultivated in poor soil and water conditions, such as in sub-Saharan Africa, parts of Asia, and the Pacific Islands. With the advancement of agronomic technology, more and more varieties of sweet potatoes have been bred to meet the needs of either the consumer or the food processing industry.

Worldwide production

According to the statistics from the Food and Agriculture Organization of the United Nations (FAO), the world’s total production of sweet potatoes in 2016 was 105 million tons. In comparison to other crops that can be consumed as a staple food, sweet potatoes are the sixth largest crop, ranking just behind corn (1060 million tons), wheat (749 million tons), rice (741 million tons), potato (376 million tons), and cassava (277 million tons). Although the cultivation of sweet potatoes is wide- spread around the world, production is not evenly distributed around the world.

China is the biggest producer of sweet potatoes in the world. In 2016 China alone produced 71 million tons of sweet potatoes, accounting for 68% of the world’s total production. Meanwhile a large number of the varieties of the plant have been cultivated in China.

Main cultivation regions and countries

Nowadays, more than 100 million tons of sweet potatoes are produced globally each year, approximately 95% of which are grown in developing countries. Asia is today the largest sweet potato-producing region in the world. More than 78 million tons were produced in Asia in 2016. Africa is the second largest producer, producing 21 million tons in 2016. The Americas, the original home of sweet potatoes, grows less than 5% of the world’s supply. Europe has only a very small sweet potato production, mainly in Portugal.

To date the ranking of the regions and continents in terms of their production of sweet potatoes is very stable. Asia is far ahead of other continents, followed by Africa and South America. As shown in Table 2.1 the world’s total production of sweet potatoes was 105.19, 103.88, and 104.57 million tons in the years 2014–16, respectively. Asia accounts for 74.72% of global production in 2016, followed by Africa (20.27%), South America and the Caribbean (2.67%), and North and Central America (1.43%). Europe and Oceania have only a very small sweet potato production, contributing only 0.86% and 0.05% of the world’s total in 2016, respectively.

Thus it is obvious that the cultivation of sweet potatoes is not widespread in developed countries in spite of the fact that they have far more advanced agricultural technologies than most of the countries in Asia and Africa.

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Health benefits of Sweet Potato.

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