Tokachi Kawanishi Nagaimo

　TOKACHI KAWANISHI NAGAIMO is yams produced in Hokkaido's Tokachi district, and are a variant of the short Yamatoimo which look like a sake bottle. Their skin and flesh are both white, and do not brown easily. They offer a crunchy texture, are pleasant to eat, and when grated into tororo, they are very sticky.

　Even when measured by an instrument, the brightness of the skin and cross section of the edible part is clearly whiter compared to yams of other origin. The high viscosity of the tororo and the crunchiness of the edible portion are due to the fact that the water content is as low as 83.1%, and the starch content is as high as 12 g out of 100 g.

　The seeds (seeds yam) of TOKACHI KAWANISHI NAGAIMO are excellent yams that have been selected and bred repeatedly to match the cultivation environment in the area, so as to bring out the characteristics of shape, color and texture. Each year has a set starting date of harvest to prevent browning and reduce bitterness. The harvested yams are packed in boxes with sawdust or individually packaged in a film by special crimping to preserve the moisture and the white appearance by cushioning before being shipped.

　The climate of the Tokachi, the production area, is cool and has long sunshine hours and a large temperature difference between day and night in summer. Apparently these are the reasons why the yams can grow slowly, the content of starch and other ingredients increases, and the production of polyphenols which causes browning is suppressed, resulting in white skin and flesh. In addition, the soil in this area is a volcanic ash layer from volcanoes around the Shikotsuko caldera; it is said that this enables drainage and is suitable for maintaining the short sake bottle shape of the yam.

　Cultivation of TOKACHI KAWANISHI NAGAIMO began at the same time the "Kawanishi Vegetable Union" was launched in 1971. Market needs then rapidly increased for the local specialty in this area, and since around 1985, production in the Tokachi area has expanded.

　Production volume exceeded 10,000 tons in 1991, and in the following year, sorting areas and storehouse were upgraded for better maintenance of quality and stabilization of shipments. From that time onwards, the number of overseas inquiries also increased, and in 1999, exports to Taiwan and other East Asian regions began. They are highly praised especially by the wealthy people in those regions, for its whiter appearance and better taste.