How long can pesticide hazards hide?
How long does the vegetable bubble make, the pesticide can be removed?
Pesticide residues in vegetables are an important issue in food safety. Especially in summer, it is the peak period of vegetable consumption and the active period of pests. In order to catch up with business opportunities, producers either use super-concentration pesticides to kill insects or harvest pesticides in advance, resulting in a large number of pesticide residues in vegetables exceeding the standard. According to statistics, under normal circumstances, the pass rate of pesticide residues in summer vegetables is more than 20% lower than that in winter. In order to reduce the pesticides on vegetables, people have come up with a variety of methods: drying in the sun, blisters, washing with rice, etc., but are these methods really effective, how many pesticides can be removed? The College of Food Science at China Agricultural University recently conducted an experiment to help people find the best way to remove pesticides.
Since the pesticide is mainly attached to the surface of fruits and vegetables during the spraying process, as long as the effective washing and processing methods are adopted, the residual amount of the pesticide can be reduced, and the edible safety of the vegetables can be ensured.
Soaking and rinsing with water can reduce the number of pesticide residues, and the longer the bubble time, the less pesticide residue. Tests have shown that 15 to 60% of pesticide residues can be removed by soaking the vegetables with tap water for 10 to 60 minutes and then washing them a little. Soaking with a special vegetable and fruit detergent is more effective in reducing the adhesion of pesticides. Dilute the detergent in water at a ratio of 1:200 and soak the fruits and vegetables. Within 10 to 60 minutes, the pesticide residue can be reduced by 50%-80%; especially in the first 10 minutes of soaking, the pesticide residue is very obvious, which can be reached. About 50%. Then, wash it a little and rinse it off with water to remove the pesticide residue.
High-temperature heating can also decompose pesticides, such as boiling water or oil. Experiments have shown that some heat-resistant vegetables, such as cauliflower, beans, green peppers, celery, etc., can be washed with boiling water for a few minutes, which can reduce the pesticide residue by about 30%, and then remove the vegetables by high-temperature cooking. % of pesticides.
In addition, washing rice with rice and proper sun exposure can also play a role in reducing pesticides on vegetables. But the rice water is best used once or twice because the surface of the rice contains potassium, so the first or twice of the rice water will be weakly acidic, but then it will start to change to alkaline, and the pesticide is only in the acidic substance. Will lose some toxicity. Sunlight can cause some pesticides in vegetables to be decomposed and destroyed. According to the measurement, when the vegetables are exposed to sunlight for 5 minutes, the residual loss of organochlorine and organic mercury pesticides can reach about 60%.
Vegetable peeling can of course also reduce pesticide residues, but it also causes loss of vitamins and minerals in the skin. Therefore, the best way to remove pesticides is to soak the fresh fruits and vegetables with detergent for 10-15 minutes, or soak them in tap water for 30-60 minutes, and rinse them with water.
Which fruits and vegetables are less polluted?
At the same time that the “Poisonous Garlic” incident has attracted people’s attention, people are also trying to find ways to distinguish the contaminated fruits and vegetables from the appearance.
Professor Li Lite, a doctoral tutor at the College of Food Science, China Agricultural University, said that it is impossible to distinguish whether the pesticides are excessive in terms of the shape and color of the vegetables. To reduce the health hazards of contaminated fruits and vegetables, it is first necessary to understand which vegetables and fruits are easier. Being polluted.
Professor Li said that in general, fruits and vegetables that are more prone to insects and insects are more difficult to control, and are often more serious pesticides. For example, apples, pears, plums, grapes, strawberries, watermelons, oranges, bananas and other pesticide residues in fruits are more serious, while shelled fruits such as litchi and longan are less polluted. The more polluted vegetables are leafy vegetables and fine vegetables such as Chinese cabbage, green vegetables, chicken feathers, leeks, spinach, rapeseed, etc., while rooting vegetables, melons, and fruits (such as potatoes, pumpkins, cucumbers, bitter gourds, tomatoes, and melons). Onions, etc.) are relatively less polluted by pesticides, and the nutrients of these vegetables are also higher.
Professor Li believes that there is no scientific reason for the saying “buy vegetables and buy insects without pesticides.” Because it is difficult for a vegetable farmer to kill all the pests at the same time, it takes a long time for the pests to develop resistance. When the vegetable farmers spray the medicine, they will escape, and then “kill will come back.” Therefore, there is no pesticide residue left on the vegetables. Moreover, the vegetable skin has a layer of wax that acts to prevent pests and toxic substances. Once the vegetable epidermis is damaged, pathogenic microorganisms such as various bacteria will take advantage of it, which is not conducive to human health.
As far as small tomatoes and large tomatoes are concerned, Professor Li humorously said that small tomatoes are produced by foreigners in order to pay attention to eating. If we do not pay attention to eating at home, it is best to choose large tomatoes. Because the same weight of small tomatoes is much larger than the surface area of large tomatoes, the area of pesticides to be sprayed is also large, and the small tomatoes of the same pulp weight, because of the proportion of their peel, much more than the large tomatoes, nutrition Not as big as a tomato.
In addition, effective methods of cleaning fruits and vegetables can also reduce pesticide contamination.
Professor He Jiguo from the College of Food Science, China Agricultural University believes that the cleaning methods of different vegetables and fruits are strictly different. For example, cleaning eggplant, green peppers, and fruits, etc., people are used to gently washing the surface with their hands. Although this can remove some pesticides, they also remove the natural wax on the surface. If they are soaked for a long time with water, It is easy to make residual pesticides infiltrate into the inside of vegetables or pulp. Therefore, fruits and vegetables such as eggplant, apple, grape, strawberry, etc. are best washed with running water, and then equipped with a detergent for cleaning pesticides. The leafy vegetables, because the leaf is not convenient to clean by hand, the wax on the surface is not removed, it plays a role of isolation, the pesticide is not easy to infiltrate, so the leaf vegetables can be directly soaked, which can be reduced The role of pesticide residues.
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