25 January 2018

Popularity of sweet potatoes in Taiwan

What really are "Sweet potatoes"?  
Sweet potatoes (Ipomoea batatas) are very popular in Taiwan. What's interesting, this crop didn't originated from Taiwan or Asia, but it comes from America. It's called “sweet potato”, although it's not related to potatos (latin: Solanum tuberosum).
Ipomoea batatas is native to tropical regions of America. There are about 50 genera and more than 1,000 species of Convolvulaceae (morning glory), mostly herbaceous vines, but also treesshrubs and herbs, but Ipomoea batatas is the only crop plant of major importance in the world. Another species of Ipomoea in Taiwan - Ipomea aquatica (water spinach) is also very important as greens. Aside from sweet potato and water spinach, many species of Convolvulaceae are poisonous.

Sweet potatoes are mostly used as root vegetable, but the young leaves and shoots can also be eaten as greens. The edible tuberous root is long and tapered, with a smooth skin with color of yellow, orange, red, brown, purple, or beige. Its flesh ranges from beige through white, red, pink, violet, yellow, orange, and purple.

The origin and domestication of sweet potato is thought to be Central or South America, between the Yucatán Peninsula of Mexico and the mouth of the Orinoco River in Venezuela. In Central America, sweet potatoes were domesticated at least 5,000 years ago. Sweet potatoes are cultivated throughout tropical and warm temperate regions wherever there is sufficient water to support their growth.
After Christopher Columbus discovered Americas, he introduces it to Isabella I of Castile in 1493, and introduces to Island of Hispaniola (Haiti/Dominican Republic) in 1508. Sweet potatoes were quite adaptable to Spanish climate and the sweet taste has made this crop popular in Europe.
At that time, in addition to being a delicacy on the table of wealthy people, the sweet potato in Europe was also rumored that the it could have medicinal effects. At the time, Europeans believed that sweet potatoes could speed up menstrual periods and the production of milk for women, while it has aphrodisiac effects on men.
The Henry VIII of England is convinced of the aphrodisiac effect of sweet potatoes, and particularly likes the sweet potato pie with spices and sugar.

candied sweet potatoes

Sweet Potato in Taiwan
The sweet potato may have been introduced into Fujian via Philippines (which was Spanish colony). In the 1580s, Chen Zhenlong brought sweet potatoes back from Luzon Island. The growing of sweet potatoes was encouraged by the Governor Chin Hsüeh-tseng. After its introduction to China, it was mainly spread in Fujian and Guangdong during the first hundred years. After sweet potato saved Chinese people from a major crop failure, it began to spread to Jiangxi, Hunan, and Zhejiang in the 17th century. In the middle of the 18th century, it also spread to the Yellow River Basin and further north. However, when the sweet potato is in the north, it's necessary to dig up the roots and keep it in the cellar during the winter for storage.

As a high-yielding hardy crop and suitable for cultivation in south of the Nanling Mountains area almost every year, the “Relief Book for Saving the Famin" written at the end of the nineteenth century stated that sweet potatoes can be planted from January to August and can be harvested up from the summer solstice to the beginning of winter.
It's not clear when sweet potatos were introduced to Taiwan. The first record of sweet potato cultivation in Taiwan was written by Chen Di in his book "Dōng Fān Jì" written in 1603, suggesting that sweet potatoes is growing in Taiwan before that time. However, sweet potatoes was not used as staple food around that time, but classified as vegetables.

Sweet potatoes gradually become staple food for aboriginal people. People from Bunun tribe (布農) even include the time for plant sweet potatoes (April) and Sweet Potato Festival (moraniyan/masuadhutan, November/December) in their calendar.
During the Dutch colonial era, Dutch didn't have much interest in sweet potatoes, they mainly encouraged indigenous people to grow rice and sugarcane. Ironically, it was sweet potatoes helped Koxinga to defeat them. Koxinga and his army besiege the Fort Zeelandia for nine months by growing sweet potatoes. There is also a legend saying that he invented oyster omelette. 

At room temperature sweet potatoes sprout quickly. People in Taiwan invented a way for long-term storage: they grate sweet potatoes and sun-dried them. Dried grated sweet potatoes can be stored for at least a year.
Dried grated sweet potatoes accompanied Taiwanese people throughout the Qing dynasty, Japanese occupation period and the early stage of Chinese Nationalist one-party rule.
Just before World War II, Japanese people discovered that the sweet potato starch can be fermented to producing ethanol, methanol, butanol and acetone. The plant for producing these organic solvent, which was located in Chiayi, was destroyed by US Army Air Force during war. Sweet potatoes also become a substitute for staple food at that time.

The most prosperous period of sweet potato cultivation in Taiwan was between 1950-1970, when the cultivated area was 200,000 to 400,000 hectares and the annual output was between 200 to 340 million metric tons. At that time, it was mainly used as feed for livestock and staple food supplements. The Agriculture and Food Agency promoted “millets, pig raising, and rice farming.” Using sweet potatoes produced in winter to feed pigs, pig excrement can be used as compost to increase rice production.
Sweet potatoes gradually faded from the table. The proportion of sweet potatoes as staple food dropped from 40% in 1945 to 25% in 1950–1960 and then dropped to 19% in 1965, while livestock feed use increased from 35% to 50%. Later, it was replaced by imported corn in livestock feed use, and the planting area of sweet potatoes fell. The consumption of sweet potatoes as staple food and leafy vegetables increased in recent years as a healthy diet trend and sweet potatoes became second only to rice.
Why Taiwanese are called “Sweet Potatoes”?
The first one to propose in the official literature that the island of Taiwan is shaped like a sweet potato is probably Professor Yasumoto Yamamoto. In addition to describing the shape of Taiwan with sweet potatoes, he also uses eucalyptus leaves. According to oral history of the Taiwanese in the Japanese occupation era collected by history scholar Xu Xueji, it probably started during Japanese occupation era. At the time, Taiwanese traveled to areas of China that was controlled by Japan to work faced a difficult situation: on the one hand, they were regarded as pro-China by the Japanese; on the other hand, they were regarded as pro-Japanese by the Chinese. Therefore, they often refused to say that they came from Taiwan and all of them just use the nickname “sweet potatoes” to identify themselves.

It may also be because the people from other provinces came to Taiwan and saw that Taiwanese people mostly eat sweet potatoes as their staple food. They then nicknamed the Taiwanese people as “sweet potatoes” and said that eating sweet potatoes was making them dumb. When the people from other provinces first arrived in Taiwan, they couldn’t distinguish between the sweet potato and the taro, and they often end up buying taros when they want to buy sweet potatoes. Therefore, people from the other provinces were nicknamed as "taro".

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