The food we should not throw them away, however, there are some that should not be reheated, either because they lose their nutritional value or because they can poison us.
Which foods should not be reheated and why
Chicken
Chicken is a rich source of protein. When reheated the composition of these proteins changes, they are broken down in different ways and there is a risk of unpleasant stomach disorders. In addition, the chicken loses nutritional value. The best way to eat it the next day is cold, in a salad or in a sandwich. If we insist on heating it, we must do it at a low temperature and for a long time, in order to make sure that all its parts are heated equally.
Spinach
Like most leafy vegetables, spinach is rich in iron and nitrates. Nitrates, if reheated, are converted to nitrites and other substances (nitrosamines), which are considered extremely carcinogenic. Although research shows that these vegetables are not affected by microwave ovens, it is best to avoid reheating them.
Eggs
Eggs contain protein and components of high biological value, but when reheated they become toxic to the human body, significantly burdening the digestive system.
Mushrooms
It is good to eat mushrooms the same day we cooked them, so we make sure to cook an amount that we know we will eat, not more, because they contain proteins vulnerable to enzymes and microorganisms, which can disrupt our digestive system. They are kept in the refrigerator, but not for more than 24 hours and it is ideal to eat them cold. The same goes for foods that contain mushrooms, such as risotto or soups.
Rice
There are bacteria in rice that grow when it stays for a long time at room temperature and are not removed by heating. Ideally, the rice should be eaten as soon as it is cooked, while if it needs to be refrigerated, this should be done within an hour of the time it was cooked. It should also not be left in the fridge for more than a day, while when we reheat it, make sure that it is well heated and there are no signs of it still cold from cooling.
Beets
Beets also have a high content of nitrates and as with spinach, if we reheat them, the nitrates are converted into carcinogenic nitrites. If you have leftovers, it is better to eat them cold.
Celery and carrots
It is usually in the soup that is left over and we will put it in the fridge. Like most vegetables, the nitrates they contain, if reheated, are converted to dangerous nitrites. If we want to heat our soup, it is good to take out the celery and carrots and add them to our plate after heating.
Potatoes
Potatoes lose much of it nutritional value which have, when left exposed to room temperature for a long time, while favoring the growth of butyl clostridium, a dangerous bacterium that can cause severe toxic poisoning (botulism). This bacterium is not killed by a simple "warm up". If we realize that the potatoes we cooked are "many", the ones we will not eat should be stored immediately in the refrigerator and not left on the counter until they cool.
via: Enimerotiko