The Guangdong Provincial Food Safety Network recently issued a consumer warning, advising the public not to purchase so-called "farm-fresh" vegetables, as many of them have been "disguised."
These vegetables do not look very fresh; some have yellowed and withered leaves, while others have roots beginning to rot. To hide their defects, vendors tear off the yellowed leaves and cut away the rotten roots. After this "processing," the vegetables appear "fresh" again, but health hazards have been silently introduced...
This is because some leafy vegetables, such as spinach and bok choy, contain a certain amount of nitrate, which is normally harmless to the human body. However, when leafy vegetables rot or when cooked leafy vegetables are stored for too long, the nitrates in the leaves undergo a chemical reaction and turn into nitrites. Consumption can lead to poisoning. Even if the rotten parts are removed, the nitrite content in the remaining parts will still be higher than normal levels. Therefore, consumers must not covet this so-called safe freshness, as it could instead pose a threat to their health. In fact, selecting safe and healthy vegetables is not difficult; you just need to master the following three rules.
1. Look at the color. There is a wide variety of vegetables, each with different nutritional values. Generally, they can be divided into two categories based on color: dark green leafy vegetables, such as spinach and amaranth; these vegetables are rich in carotene, vitamin C, vitamin B2, and various minerals; and light-colored vegetables, such as Chinese cabbage and lettuce. Some light-colored vegetables are rich in vitamin C, but their carotene and mineral content is lower.
Pay attention to vegetables with abnormal colors, such as leaves that have lost their usual green and turned dark green, or abnormally bright green edamame. These vegetables may have been sprayed or soaked in methamidophos pesticides before harvest and should not be purchased.
2. Look at the shape. Vegetables with a normal shape are generally conventionally cultivated and not treated with hormones or other chemicals, so they can be eaten with confidence. "Abnormal" vegetables may have been treated with hormones. For example, with chives, if the leaves are particularly wide and thick—twice as wide as regular broad-leaf chives—they may have been treated with hormones during cultivation. Chives that have not been treated with hormones have narrower leaves and a richer aroma when eaten.
3. Look at the freshness. Many consumers believe that vegetables with many insect holes in their leaves are safe to eat because they were not sprayed with pesticides. In fact, this is unreliable. Whether a vegetable is susceptible to pests depends on its specific composition and aroma. Some vegetables are particularly favored by pests, with well-known examples being green vegetables, Chinese cabbage, cabbage, and cauliflower. They have to be frequently sprayed with pesticides for control, inevitably becoming "multi-pesticide vegetables" with high levels of contamination.
The amount of fertilizer applied to various vegetables also varies. Excessive application of nitrogen fertilizers (such as urea and ammonium sulfate) can cause serious nitrate contamination in vegetables. Market inspections have found that the nitrate content in vegetables, from highest to lowest, is as follows: root vegetables, tuber and bulb vegetables, leafy vegetables, cabbage-type vegetables, onion and garlic vegetables, legumes, gourds, eggplant and fruit vegetables, and edible fungi. The pattern is that the contamination levels in the roots, stems, and leaves of vegetables are much higher than in the flowers, fruits, and seeds. This pattern can guide us in making correct vegetable choices, encouraging us to eat more gourds, fruits, legumes, and edible fungi, such as cucumbers, tomatoes, edamame, and shiitake mushrooms.