1. Can any rice cooker bake cake, or only certain models?
When people hear "cake in a rice cooker," they might think any model can do it. This is not true. In November 2019, a multi-rice cooker was released with 9 automatic modes. These modes allowed users to cook stew and cake, showing that a tool for rice can handle other dishes [2].
However, articles on parenting information explain that cake-making is only suitable for models that have a specific "cake" or "dessert" menu. If a pressure IH (induction heating) model does not have a cake mode, there is a possibility of danger [3]. Some rice cookers are not designed for cooking anything other than rice. The advice is to check the manufacturer's website or manual to be sure [3].
So, whether you can bake cake depends on the specific menu of the machine, not just the name "rice cooker." Before looking at other foods, let us look at the main job of the machine: cooking rice.
Safety Note: Parenting articles state that cake-making is basically only for models with a cake menu. For pressure IH models without a cake mode, there is a risk of danger. Always check your specific model's manual before trying new recipes.
2. How detailed are the rice cooking menus on a rice cooker?
Before discussing cake, let us look at the primary function of a rice cooker. In 1955, Toshiba released an automatic electric rice cooker. It used a time switch to cook rice at a set time. Toshiba explains that within 4 years of its release, about half of all households had one. This greatly reduced the burden of housework and changed daily life [1].
Today, rice cookers have menus for different types of rice and ways of eating, such as white rice, brown rice, porridge, and steamed rice with ingredients. However, the number and names of these menus vary by model. The rice cooker changes how it cooks based on the type of rice. Cake and stew are also made using specific menus for each model. So, what happens with foods that do not have a specific menu?
3. Why does Hitachi say not to make jam in a rice cooker?
We return to our main question. If some models can make cake, why is jam forbidden? Hitachi’s rice cooker usage notes state that you cannot cook various foods like you would in a commercial pressure cooker. The banned items include foods that expand during heating, such as kamaboko (fish paste), beans, and noodles. They also ban foods that suddenly foam, dishes with large amounts of oil, dishes that become thick like curry roux, and foods that foam, such as jam. Cooking food inside plastic bags is also forbidden [4].
The reason given is the risk of burns. Food or hot water may splash out, causing burns. Also, the pressure regulating valve may get clogged, causing the lid to open suddenly and cause burns. The pressure regulating valve is a part that adjusts pressure [4].
Jam is banned because it is a food that foams. The difference between cake and jam is that cake is made on models with a specific menu, while jam is banned as a "foaming food." This is specific to Hitachi’s notes. You must check the manual for other companies and models.
Safety Note: The reasons for banning these foods are the risk of burns from splashing food or water, and the risk of burns from the lid opening suddenly if the pressure valve gets clogged. Hitachi’s notes ban expanding and foaming foods for these safety reasons.
4. How long can rice stay good in a rice cooker's keep-warm mode?
Rice cookers have another daily job besides cooking: keeping warm. The inside of a rice cooker in keep-warm mode is kept at about 60°C to 70°C (140°F to 158°F) so that warm rice is always ready [5].
Experts suggest that you can enjoy the taste of freshly cooked rice within about 3 hours. It is considered good to eat within 6 hours. However, many people actually keep rice warm for about 12 hours. 12 hours is twice as long as 6 hours [5]. How long rice stays tasty in keep-warm mode depends on the cooker; 6 hours is a guideline.
For long periods, Hitachi’s Q&A suggests setting the keep-warm temperature to a lower level. Then, press the reheat button about 10 minutes before eating. Keep-warm temperatures differ by manufacturer and model [6]. Can this ability to hold 60°C to 70°C be used for things other than rice?
5. How do you know meat is fully cooked in low-temperature cooking with keep-warm?
Some recipes use the keep-warm function for low-temperature cooking of meat. The important question is: How do you know the meat is "fully heated"?
A food safety newsletter from Gifu Prefecture (December 2021) states that to fully heat meat, the center must reach 75°C (167°F) for 1 minute. Or, it needs equivalent heating, such as 63°C (145°F) for 30 minutes. It warns that in low-temperature cooking, you cannot tell if the meat is done by looking at it. The required temperature and time change depending on the machine and the thickness of the meat. Incorrect methods may lead to undercooking [7].
A document from the Sumida Ward Public Health Center shows equivalent heating conditions to 75°C for 1 minute. These include 63°C for 30 minutes, 65°C (149°F) for 15 minutes, 66°C (151°F) for 11 minutes, 67°C (153°F) for 8 minutes, 69°C (156°F) for 4 minutes, and 70°C (158°F) for 3 minutes. For example, if you set the cooker to 63°C for a 300g chicken breast (3cm thick), it takes 70 minutes for the center to reach 63°C. Then, it needs another 30 minutes of heating. This is a total of 100 minutes, or 1 hour and 40 minutes [8].
This table shows the combination of "set temperature" and "required heating time at that setting." It takes extra time for the center of the meat to reach the set temperature. The higher the temperature, the shorter the required heating time. Since rice cooker keep-warm temperatures vary by model, the conditions are not always the same. What official documents indicate is that results differ depending on the model and conditions.
Safety Note: The Sumida Ward Public Health Center document lists equivalent heating conditions like 63°C for 30 minutes. Therefore, official documents do not say "rice cooker keep-warm is always safe" or "rice cooker cooking is forbidden." You must follow specific conditions.
6. How can you find what is allowed and what to avoid in your rice cooker manual?
Look at the instruction manual for your home’s rice cooker. Find the sections on "usable menus" and "cooking you must not do." If you do not have a paper manual, it may be on the manufacturer’s website.
Read three things: the list of menus, the banned cooking methods, and the guidelines for keep-warm temperature and time. If you use a Hitachi rice cooker, compare it with Hitachi’s notes to find similarities and differences. You will see that the safety line changes depending on the model.
Use the manual to check what is safe to cook. Do not try cooking foods that are not listed in the manual. Rice cookers release hot steam.
Safety Note: For safety, it is not recommended to actually try cooking foods that are not in the manual.