Watermelon can be eaten in the refrigerator overnight, depending on whether the watermelon has not deteriorated. If it has not deteriorated, it can be eaten normally, such as acidity or color change and other abnormalities, it is not recommended to eat. Watermelon in the refrigerator can only inhibit the reproduction of bacteria, and can not eliminate bacteria, and watermelon itself contains fructose, glucose and other nutrients, can provide raw materials for bacterial growth and reproduction, and bacteria active will cause diarrhea, vomiting and other discomfort, causing food poisoning. First of all, when the watermelon is not cut, the interior itself is in a sterile environment, but if you use an unclean knife or cutting board when cutting the watermelon, such as a knife or cutting board that has cut meat is not clean, then the bacteria will be brought to the surface of the watermelon, and the watermelon is a good medium for bacteria, ideal for the growth and reproduction of bacteria, which is very easy to cause spoilage. This situation is still recommended to consume as soon as possible, it is not recommended to store for too long. Secondly, cut watermelon in 4-8 hours, whether at room temperature, or refrigerator storage, can be safe to eat; cut watermelon is best not to place more than 24 hours, after 24 hours the total number of watermelon bacteria multiplied, consumption may lead to food poisoning, nausea, vomiting, diarrhea and other gastrointestinal symptoms, serious cases may also lead to food poisoning. In addition, cut the watermelon if you need to place more than 8 hours, it is recommended to wrap the plastic wrap and then put in the refrigerator to avoid cross-contamination of watermelon and other food in the refrigerator. In addition, take out the watermelon from the refrigerator when eating, to cut off about 1cm thickness of the surface layer, which can effectively reduce the amount of bacteria. At the same time, observe the watermelon from the refrigerator out of the discoloration, taste and other deterioration, so you can not eat.