Traditionally, rice was eaten at every meal in Japan; most modern rice cookers can be set ahead by a timer, so that rice will be ready for the morning meal. The rice cooker can also keep rice moist and warm. Rice kept warm like this remains edible for several hours, so that rice need be made only once per day.
Features and specifications
For the modern home rice cookers, the smallest single-person model cooks 1 rice cup (180 ml), whereas the largest cooks 10 rice cups (1.8 liters). The prices vary greatly, depending on the capacity, features, materials used, and the country of origin.
These inventions include, e.g., microprocessor-controlled cooking cycles, employing pressure cooking, utilizing induction heating (IH) that can generate heat directly within the inner cooking bowl itself (all the IH-type models are microprocessor-controlled), employing a varying pressure control mechanism (named the "dual-pressure" method) that creates repeated pressure/release cycles during the cooking, using various materials (e.g., copper, pure carbon, ceramic, diamond powder coating) for the inner cooking bowl because of their higher heat conductivity, utilizing more than one induction heating element, or employing a mechanism to collect and return the boiled over liquid to the inner rice bowl. The rice cookers which are very large to store tons of rice are used in places like Guruvayur.
The pressure-cooking models can raise the water's boiling point higher, e.g., from 100 °C at 1.0 atm up to about 110 °C at 1.4 atm, which speeds cooking. They are also suitable for cooking brown rice (which contains oils and bran fiber that cook differently from pure white rice starch). The pressure-cooking models can also be used in high altitude areas.
The majority of modern electric rice cookers are equipped with a stay-warm or keep-warm feature, which keeps the rice at an optimal temperature for serving without over-cooking it. Some gas cookers also have electric stay-warm mechanism.
Many models feature an ability to cook sticky rice or porridge as an added value. Most can be used as steamers. Some can be used as slow cooking pots. Some other models can bake bread or in some cases have an added function to maintain temperatures suitable for fermentation of bread dough or yogurt. Likewise, depending on the model, these days it is common to see many added functions other than cooking rice.