Shima tofu

The earliest recorded mention of Shima Tofu dates back to 1683, noting that a large number of shops in the city of Naha were already selling it at that time.

Because pig farming was thriving in Okinawa, the production of okara, a by-product of tofu making used as pig feed, was also common, leading to the widespread manufacture of tofu.^[4]

In the Meiji period, there was even a street in Itoman (糸満市) so densely populated with tofu vendors that it came to be known as "Tofu Town" (トーフマチ, Tōfu Machi).

Millstones used to grind soybeans were often made from andesite sourced from Iōtorishima, where the rock was abundant.

Following Okinawa's reversion to Japan in 1972, the Food Sanitation Act mandated that tofu be sold soaked in water. However, as a result of petitions emphasizing the importance of preserving local food culture, a special exemption was granted in 1974 allowing the sale of warm, freshly made tofu without immersion.

Today, Shima Tofu remains widely consumed in Okinawa and Kyushu. According to a 2012 household survey, annual household expenditure on tofu in Okinawa averaged 5,670 yen, significantly higher than the national average of 4,613 yen.^[5]

Soybeans that have been thoroughly dried through methods such as sun-drying are first split in half using a millstone or specialized machinery. The split soybeans are then exposed to wind while being sifted, which removes the hulls. These processes allow water to quickly penetrate the soybeans. After manually removing the germ axes from the split soybeans, they are soaked in water for three to four hours. Grinding them with added water using a grinder produces raw soybean pulp.^[6]

A defining feature of traditional Shima Tofu is the namashibori method, where okara and soy milk are separated at the raw pulp stage. This approach, including the initial crushing of the soybeans, shares similarities with methods found in Southeast Asian countries such as Vietnam and Malaysia. Compared to the nishibori (煮しぼ) method, where separation occurs after boiling, the namashibori technique makes soy milk extraction more labor-intensive and results in lower yield. However, extracting at a lower temperature suppresses the release of undesirable flavors caused by isoflavonoids and saponins, providing a distinct advantage.^[6]

The soy milk obtained through namashibori is transferred to a large traditional iron pot (地釜, jikama) and simmered for about an hour to develop its aroma. During this process, any foam that forms is removed. Then, a coagulant such as seawater or nigari (にがり) is added. The resulting soft, fluffy tofu at this stage is called yushi-tōfu (ゆし豆腐), which can also be eaten directly with soy sauce.^[6]

The yushi-dōfu is poured into a mold lined with cloth, and the water is drained, resulting in finished Shima Tofu.

While traditionally sold warm, in recent years packaged and refrigerated versions have become available, offering longer shelf life and easier inventory management for retailers.^[6]