Leafy green vegetables commonly consumed all contain varying amounts of nitrates, which can be converted into nitrites by intestinal bacteria after ingestion. Generally, when leafy greens are stored for too long, or when leftovers are not consumed promptly, not only is there a severe loss of vitamins, but the nitrite content also increases significantly, and this cannot be removed by heating.
Leafy greens that have been stored for too long should not be eaten
In daily life, many "customary" habits are actually very unhealthy. For example, in the hot summer, people let cooked food cool down before eating, or to stay away from the heat in the kitchen, they cook large batches at once to eat for the next meal or the day after.
This causes a significant loss of vitamin C and B vitamins in the food. Research has shown that stir-fried vegetables can lose 30% of their vitamin C after being left for half an hour, and up to 50% after one hour.
Nitrites can combine with protein breakdown products in the body to form carcinogenic substances—nitrosamines. Therefore, leftover leafy vegetables should not be reheated and eaten. Leftover meat dishes generally do not produce nitrites, but they may be contaminated with bacteria. They can be rinsed with water, then seasoned and cooked again.
Fermented foods can enhance disease resistance
When making different types of flour-based foods, the loss of nutrients also varies. For example, when boiling noodles or dumplings, some water-soluble vitamins can dissolve into the noodle or dumpling broth (so you should drink the broth).
When making baked flatbreads, about 20% of vitamin B2 is lost. Using the traditional method of adding alkali to leaven the dough can destroy B vitamins. However, if fresh yeast is used for leavening, it not only prevents the loss of vitamins but can also produce B vitamins. Furthermore, yeast contains an active substance that can activate the activity of human macrophages, increasing the body's resistance to disease. It can also remove some phytic acid from the flour, so it is better to eat more fermented foods.
Rinsing rice twice loses 80% of vitamin B1
When rice is scrubbed, vitamins and minerals can be lost. The more times it is washed, the harder it is scrubbed, the longer it is soaked in water, and the higher the water temperature, the more nutrients are lost.
According to relevant experiments, after one washing, rice loses 70% of its vitamin B1, and after two washings, the loss is 80%. Protein loss is 10%, and mineral loss is about 14%. Therefore, when cooking rice, you can rinse it lightly 2-3 times according to its cleanliness.