It is now the height of winter, and fruits and vegetables bought from the morning market may inevitably be frost-damaged. Frozen produce should be consumed with caution, as some fruits and vegetables not only lose their nutritional value after being frozen but can also produce toxic substances.
In terms of common vegetables, toxic substances can be produced at low temperatures, making them unsuitable for consumption. For solanaceous vegetables like eggplant and tomatoes, the ideal storage temperature is between 7°C and 10°C, with a minimum temperature above 0°C. If the temperature is too low, it can damage the plant tissue, causing the loss of vitamins, amino acids, and other components, and the texture will be greatly compromised. When frozen fruits and vegetables thaw, they can also produce some toxic substances. For example, frozen Chinese cabbage can contain nitrites and nitrates. When the nitrite content in frozen cabbage exceeds 2.5 mg/100g, it can cause poisoning in humans, leading to symptoms such as headache, dizziness, nausea, and vomiting. In severe cases, it can even lead to coma. Therefore, if cabbage is frozen, it must be thoroughly cooked to destroy the internal nitrites before it can be eaten.
We recommend that you buy vegetables and fruits from regular supermarkets or farmers' markets, as these places have relatively complete insulation facilities. Also, even if the produce you buy is not frozen, it is best to let it "acclimatize" in a cool place at home after bringing it back.