History of Roasted Soy Flour in Japan . It is not known when roasted whole (full-fat) soy flour ( kinako ) was introduced to Japan from China, nor are any reference to it in Japanese known. Regular kinako, though the two characters forming the word mean "yellow flour," is actually tan or beige in color. A similar product called uguisu kinako ("nightingale roasted soy flour") is light green, since it is made from dry soybeans having a green seed coat.
Although it is quite possible that roasted soy flour was introduced to Japan over 1,000 years ago by Chinese or Japanese Buddhist monks, the earliest legendary reference to the product in Japan places its origin roughly between 1050 and 1100. A famous general from Kyoto named Hachiman Taro Yoshiie, who is reputed to have been one of the first people in Japan to develop natto (see Chapter 38) is also credited with having developed Japan's first concentrated, high-energy processed food called hyoryogan ("soldiers food pellets") made from a mixture of ground roasted soybeans, buckwheat groats, and hemp seeds, shaped into lightweight little balls to be carried by soldiers on long marches. Hitler developed a similar food prior to World War II, his famous Nazi Food Pills (Ohta 1975). The Japanese Encyclopedia of Food and Drink (Motoyama 1958) states that since olden times roasted soy flour has been mixed with sugar and widely used in Japanese confections such as Ohagi no Mochi , Abekawa Mochi , Kinako Mochi , and Kinako Dango , each consisting of fresh mochi (pounded glutinous rice cakes) dusted with roasted soy flour. Kinako Amé , whose prototype was developed in China and described in Japan in the Wakan Sansai Zukai (1711), probably gradually became popular after that time. The earliest roasted soy flour in Japan was probably made in farmhouses by roasting whole dry soybeans in an unglazed earthenware pan ( horoku ) over an open fire, then grinding the roasted beans into a flour between the same hand-turned millstones used to grind the soaked soybeans for making farmhouse tofu, or to grind buckwheat for buckwheat flour or noodles. During the late 19th or early 20th century it came to be made on a small commercial scale, the soybeans eventually being roasted over an open fire in a rotating screen drum. In 1923 Piper and Morse reported that a soy coffee, made from roasted soy flour, had been introduced in Japan. During his trip to Japan in 1929-31, William Morse made frequent mention of roasted soy flour and took many photographs of confections made with it. In 1933 he noted that "In East Asia there are popular health drinks made from roasted soybeans." He was probably referring to the soy coffee (Dorsett and Morse 1928-31).
The first report in English about roasted soy flour production in Japan was by A.K. Smith in 1958. He noted that the whole (not dehulled) beans were roasted for 30 minutes or longer in a gas-fired rotating drum, cooled on straw mats, ground to a fairly fine flour, then hand packed in plastic bags. The Kinako Manufacturers Association had about 50 members nationwide, including 16 in Tokyo. The largest plant made no more than 5 tons a day. Production was seasonal, with December being the peak month, corresponding to the widespread consumption of mochi during the New Year's season. Smith recommended that the beans be dehulled before roasting. In 1969 Watanabe reported that about 12,000 tonnes (metric tons) of soybeans were used annually to make roasted soy flour and that an average plant used 200 kg of soybeans a day. Some dehulled their beans before roasting and some ground with a hammermill having a fine screen. It is difficult to know the exact size of the industry at present since the government keeps no separate statistics.