The idea
of cooking rice with electricity was first conceived in the age
of westernization during the Meiji era, and products called "electric
stoves" and "electric rice tubs" were produced experimentally at
the end of the Taisho era (mid 1920s). These were stoves and tubs
to which heating coils were attached.
In the late 1940s, Mitsubishi Electric Corporation manufactured an
electric rice cooker, a pot incorporating a heating coil inside.
Featuring no automation, this was simply a pot that used a heating
coil instead of firewood or gas. The device was inconvenient, requiring
attention from the time it was switched until the rice was done,
and sold poorly. Rather than being remembered as the forerunner of
modern rice cookers, the device was relegated to the status of a
footnote in the history of electric appliances.
In 1952, Matsushita Electric launched a Mitsubishi-type rice cooker,
which was also poorly received. Sony's offering (an electronic rice
tube) fared likewise.
Around July 1951, based on its conviction that electrical appliances
would one day become a part of daily life in Japan, Toshiba tackled
the challenge of creating a successful electric rice cooker, a product
area where leading manufacturers Mitsubishi and Matsushita had failed.
The project was led by Shogo Yamada, development manager of the electric
appliance division.
On December 10, 1956, about five and a half years after the project
began, 700 rice cookers were placed on the market. Familiar with
the history of poor sales, distributors were reluctant to sell them.
In response, Toshiba created a new distribution network (Note 1).
The rice cooker began to sell ? like rice cakes, as it were! Soon,
Toshiba was producing 200,000 a month. Four years after their introduction,
rice cookers were to be found in half the homes in Japan. In 1970,
total annual output had reached 12,350,000 cookers.
Cooking rice, the staple food of the Japanese, was part of the unavoidable
housework of housewives, in addition to cleaning and washing. It
took certain skill to make good rice. The advent of the electric
rice cooker with a timer switch not only cooked rice automatically
by a desired time, it reduced the time required for basic housework
and changed the lifestyle of the Japanese people. Toshiba's first
electric rice cooker represented the advent of a revolution in Japanese
food culture. The award-winning design remained unchanged for nine
years.
Previously, very few engineers had considered the nature of the rice
itself being cooked or the process of the cooking, regarding rice
cookers as simple devices that were turned on or off. Uncooked starch
of which the crystal structure is confirmed by X-ray crystallography
is called a starch. When this starch is heated and the crystal structure
is no longer visible, it is then called a starch or "gelatinized starch".
The purpose of processing starches is to transform a starch to a starch.
If heated at 98 degrees C for 20 minutes, all the rice in the cooker
is nicely cooked and transformed into a starch. The result of a consumer
survey indicated that the heat source does not necessarily require
adjustment, as traditionally believed. Better results were obtained
by cooking over a constant high flame.
The Toshiba project team performed a test, during the course of which
they discovered that the only necessary factor was heating the rice
for 20 minutes after it came to a boil. This finding convinced the
project team that an improved rice cooker was close to being developed.
They researchers found that potatoes begin to transform into a starch
at about 47 degrees C, and rice at 57.8 degrees C, and they performed additional
experiments. They found that, at 57.8 degrees C, it took 15 to 16 hours to
transform 1.5 kg of rice into a starch. They repeated the tests,
gradually increasing the temperature, discovering that if rice is
transformed into a starch at 73 degrees C, it remains converted. This is
now used as the principle of the insulated rice cooker. They then
continued to heat the rice at 98 degrees C for 20 minutes, which effected
a permanent transformation of the rice into a starch. The results
were verified via electron microscope, just introduced at that time.
Theory dictated that cooking rice for 20 some minutes on a timer
would result in well-cooked rice. Practice didn't bear this out.
When cooked with a prototype cooker, rice was half-cooked or scorched.
This was because the required boiling actually depended on several
variables, including the external temperature of the cooker, the
heating value, and the amount of rice or water.
The problem then came how to detect the when the rice actually begins
to boil, and how to turn off the switch exactly 20 minutes thereafter.
The solution was indirect cooking using a double pot, based on trial
and error. A cup of water was poured into the outer pot; this amount
would evaporate in 20 minutes. When the water evaporated, the temperature
of the pot exceeded 100 degrees C. This was detected by a bimetallic thermostat
and the switch was turned off. Water evaporation was used as the
timer. The idea was simple and elegant, and uniquely Japanese. The
successful rice cooker was based on countless trial and error efforts,
which involved enlisting even the president of an ice manufacturer,
Koshin-sha, and his wife, who performed experiments in their own
warehouse or in their garden in the dead of winter.
Note 1)
The issue of surplus power production posed a
significant challenge to electric power companies at the time. Toshiba
asked the companies to serve as distributors of the automatic electric
rice cooker, a request with which the companies were happy to comply.
Employees visited various homes, armed with rice cookers. Thanks
to such efforts, sales of rice cookers began to soar. (The power
surplus stemmed from the widespread replacement of carbon-filament
light bulbs with significantly more efficient tungsten bulbs, reducing
electricity demand to levels that resulted in the suspension of operations
at half of the country's power plants.)
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