Can rice left in a rice cooker overnight still be eaten?
According to experts, this situation can be divided into four cases as follows:
Case 1: If the rice remains untouched in the rice cooker after it has boiled and the lid hasn't been opened, most bacteria will have been killed. If the lid isn't opened, bacteria cannot enter, so it won't cause any harm. Although the moisture and nutrients in the rice are ideal for bacterial growth when the power is off and the temperature drops, bacteria will not grow. In this case, the rice will not spoil even if left overnight or longer.
Case 2: After the rice is cooked, you open the lid, take some rice out while it's still hot, and then close the lid again. At this time, the temperature inside the rice cooker is still relatively high, although some bacteria might enter when the lid is opened. However, the rice can maintain a higher temperature for a while after the lid is closed. During this time, the high temperature will kill any bacteria that entered from the environment. Therefore, after the temperature drops, there won't be too many surviving bacteria, and they won't multiply significantly overnight. In this case, eating the rice left overnight is generally safe.
Case 3: If you have taken some rice out and it has cooled down, but you used a clean spoon/scoop and the air in your home is well-ventilated and clean, the amount of bacteria that enters will be minimal. After one night, the bacteria won't multiply much, so you can eat it without facing any major issues, although it's not perfectly safe.
Case 4: Leftover rice that has been taken out, and you used chopsticks/spoons/forks that you ate with to scoop the rice, or if the air is more bacteria-laden, and then you put the rice back into the rice cooker. At this point, many bacteria will have entered and then been trapped inside the cooker. The moist environment inside the rice cooker provides ideal conditions for bacteria to grow, making the likelihood of the rice spoiling quite high, especially in the summer.
Thus, if the rice is cooked and left in the rice cooker without opening the lid or with the lid only opened briefly, it can be eaten and is relatively safe. However, in the third and fourth cases, it is best not to eat it.