SHANGHAI, Feb. 11 (Xinhua) -- A special type of sweet purple potato, grown from seeds once aboard China's second manned spacecraft, could be a must-choose item for young couples here on Valentine's Day.

    The new type of sweet potato, developed from seeds that mutated in outer space, has a much deeper purple color than previous generations, according to the Haikou Purple Orchid Co. Ltd., the grower, in China's southernmost Hainan Province.

    Named Purple Orchid 3, the "space" potatoes are of normal size and not much different from ordinary potatoes in sweetness and fragrance, but taste more glutinous, said company manager Chang Lingen.

    In October 2005 China's second manned spacecraft, "Shenzhou VI", completed a five-day space voyage. Apart from the two astronauts, the space vehicle carried various plant and flower seeds for experiments.

    Since purple is believed to represent nobility and romance, restaurants in the booming city of Shanghai have started offering a range of culinary delights featuring the new purple sweet potatoes, as a warm-up promotion for Valentine's Day, which couples in China often celebrate by eating out.

    The General Club of Shanghai Food and Drink Industrial Association recently invited 30 well-known local chefs to try out more than 60 possible "space potato" dishes.

    Kent KC Lee, a top chef from Hong Kong who now works in Shanghai's Carnation Restaurant, pioneered a Purple Orchid series including salad, appetizers, desserts, mini cakes and an iced drink.

    One of the most popular is the Purple Orchid cod ball, four balls of cod fish covered by purple potato crisps on a bed of decorative fruit salad.

    "Almost every table of guests tries out a dish or two in the Purple Orchid series," said Peng Yuan, head waitress of Carnation Restaurant.

    The restaurant has consumed hundreds of kilograms of the new purple sweet potatoes since it started promoting the purple series, said the restaurant's general manager Hua Guoqiang, who was confident that sales during Valentine's Day and the Chinese lunar new year holiday would be solid.

    "It tasted like rice flour for babies. I like the flavor," said Zong Zhaowang, a postgraduate student from Shanghai-based Tongji University who tried Purple Orchid juice at the restaurant.

    Unlike ordinary white potatoes that are planted in soil, the Purple Orchid 3 is cultivated on the sandy beaches of Hainan island, at 18 to 20 degrees latitude north.

    The purple sweet potato is mainly composed of fibrins and pectin, which can stimulate the stomach and intestines, experts said.