These foods can become toxic when reheated

Toxins can lead to gastrointestinal problems
If there is anything left over from dinner, it usually goes into the refrigerator. After all, you can still eat the next day or the day after that, right? Yes, but you have to be careful, especially with some food.

Not all of them are suitable for reheating in a saucepan or microwave, as this can release certain toxins that can lead to gastrointestinal problems or even cause cancer. We explain which foods you should be careful with and how to store and heat them properly.

Spinach
Spinach naturally contains a lot of nitrate, at elevated temperatures it can be converted into toxic nitrite. Combined with certain protein breakdown products, carcinogenic nitrosamines can be formed, and too much nitrite can cause nausea, vomiting and diarrhoea. Therefore, the following applies:

Consume cooked spinach after two to three days - even if it has been stored in the refrigerator. Nitrite can also form when stored refrigerated for longer periods.

Only reheat spinach a second time if you have cooled down the leftovers as quickly as possible beforehand, as cold temperatures reduce nitrite formation.

If you heat spinach, you should do this in a pot for at least two minutes at over 70 degrees Celsius.

Onions, celery and beetroot
The same applies to these vegetables as to spinach because of the possible formation of nitrate. If onions, celery and beetroot are heated, toxins may be released and carcinogenic substances may be produced.

Fungi
If you store mushrooms at room temperature for a longer period of time, warming them up becomes dangerous. Due to the high content of water and protein, fungi can produce dangerous toxins that can cause nausea and vomiting.

To avoid this happening to you, you should pay attention to the following:

Do not store mushrooms in the refrigerator for more than a day.
Cool mushroom dishes quickly after cooking, frying or baking.
Only reheat mushroom dishes once at at least 70 degrees! Afterwards you should never heat mushrooms again.
Rice and potatoes
If you put rice and potatoes in the refrigerator only a few hours after preparation, bacteria can form which can lead to digestive problems and in the worst case to food poisoning.

You can avoid this in the following ways:

Place prepared potatoes and rice in the refrigerator as soon as possible after preparation.
Do not heat them in the microwave, but in a pot.
Heat the rice and potatoes - as well as other foods - evenly and completely at at least 70 degrees.

Chicken
There are two risk factors for chicken. Firstly, heating prepared cold chicken changes the protein structure in the poultry, which can cause digestive problems. Secondly, Salmonella increases when cooked chicken is stored. If you warm the meat, salmonella can be retained and in the worst case scenario, can lead to salmonella poisoning.

Do not heat chicken in the microwave.
Heat the chicken as it was originally prepared - in a pan or oven, as appropriate. It should be warmed up long enough to ensure that it is completely and evenly hot.

Eggs
As with chicken, the protein structures of eggs can change when they are warmed up and lead to gastrointestinal complaints. Salmonella can multiply if stored at room temperature.

Therefore follow the following rules:

Do not store eggs at room temperature, store them refrigerated.
Heat food with egg at least 70 degrees.