Study on Dynamics and Limits of Pesticide Residues Used in Spinach

Excessive pesticide residue is a hot and difficult problem in the quality and safety control of agricultural products. Dietary exposure assessment of pesticide residues and formulation of limit indicators are important basis for agricultural product quality supervision. Corresponding pesticide residue detectors are required for pesticide residue limits at different production stages of agricultural products. Standards are supervised.

Some researchers used the international standards for tracking pesticide residue limits in spinach as clues to analyze the status of pesticide residue standards in spinach and its processed products; studied the dynamic changes in the number of pesticides such as chlorpyrifos in soil, planting, and processing, and conducted pesticides in spinach in China. The theoretical maximum ingestion of residues was estimated; the maximum residue limits of several commonly used pesticides in spinach and its processed products were proposed based on the residue data and processing factors of the pesticides tested, and suggestions were made for the formulation and control of pesticide residue limits in spinach in China.

Ancient Chinese called spinach "red-billed green parrot", also known as Persian, red root vegetables. In the “Compendium of Materia Medica”, it is considered that eating spinach can “pass the blood, open the breasts, lower the breath, and quench thirst.” Ancient Arabs also called it "vegetables." Spinach not only contains a lot of carotene and iron, but it is also an excellent source of vitamin B6, folic acid, iron and potassium. Spinach contains a considerable amount of protein, and every 0.5 kg of spinach is equivalent to the protein content of two eggs. Spinach is also rich in enzymes.

We all know that when you have a poor face, please eat spinach regularly. It has an improvement on iron deficiency anemia. It can make people look ruddy, shine, and is therefore respected for beauty. Spinach leaves contain an insulin-like substance that acts like insulin and keeps blood sugar steady. The rich vitamin content of spinach can prevent the occurrence of vitamin deficiency such as angular cheilitis and night blindness. Spinach contains a large number of antioxidants, anti-aging, promote cell proliferation, can activate brain function, but also enhance youthful vitality, help prevent brain aging, prevention and treatment of Alzheimer's disease. A Harvard University study also found that middle-aged and elderly people who eat 2-4 times a week can reduce the risk of retinal degeneration and protect their eyesight. Spinach is longer than the human body to clean up the heat of the stomach, Chinese medicine, spinach, Gan Liang, can nourish, stop bleeding, convergence Yin, Runzao. It can prevent constipation and make people radiant.

After being cooked, spinach is soft and easy to digest, especially suitable for old, young, sick and weak people. Computer workers and people who love beauty should eat spinach. People with diabetes (especially those with type 2 diabetes) often eat spinach to help stabilize blood sugar.

After understanding the function of spinach, we returned to the topic. The formulation and control of pesticide residue limits in spinach were determined by the pesticide residue detector. The main concluding contents are as follows: 1. Analysis of the status of pesticide residue limits in spinach. Different countries have large differences in the number and distribution of pesticide MRL in spinach. Japan has set 321 pesticide residue limits for spinach, of which 163 are larger than 0.1 mg kg-1, accounting for about 50% of the total, although the positive list system is The export of spinach in China has a large impact, but there is still a lot of room to deal with the use of pesticides; in the European Union, there are about 303 residue limits set for spinach and its analogues, and 163 of the spinach are clearly defined, but less than 0.05. There are 259 mg·kg-1, accounting for about 85% of the total, which is the most stringent standard. The Codex Committee of the International Codex Alimentarius (CAC) has a total of 78 items in the spinach standard, and the limit is less than 0.1 mg/kg-1 with only 10 items, accounting for only 12.8% of the total. There are 53 residue limit indicators in the American spinach standard, and only 3 limit indicators that are less than 0.1 mg/kg-1, which account for about 5% of the total, are the most loose standards. Overall, the strictness of the limited indicators is EU, Japan, CAC and the United States. The international standards for spinach contain pesticides, fungicides, and herbicides in the international standards. There is no limit for herbicides in China's spinach standards, and the number is less than the EU, Japan, and the United States. In China, spinach and its products have limited connectivity standards and the types and quantities are not uniform. It is recommended that the pesticide residue limit indicators and decision rules in different product standards be unified.

Second, study the residue dynamics of chlorpyrifos and other pesticides in spinach cultivation and processing. Potted plants were used to study the absorption of chlorpyrifos residues in soil by spinach. It was found that spinach has a growth absorption effect on chlorpyrifos residues in soil and is positively correlated with the residual concentration in the soil. Export enterprises should use spinach for the cultivation of spinach. Pesticide residue testing was performed on the soil to avoid export of chlorpyrifos residues in soil absorbed by spinach. The field degradation results of the tested pesticides showed that the malathion degradation rate was fastest, and the initial residue was 4.5 mg kg-1, which was lower than the national standard of leafy vegetables 8 mg kg-1, therefore, the leafy vegetables countries Standards are not directly applicable to spinach standards; the current standard of 0.1 mg/kg for chlorpyrifos in leafy vegetables is too stringent to be used in the production of spinach; compounded pesticides such as propamocarb and metalaxyl are used in spinach. The residue limits, residue limits, and safety intervals should be set in consideration of the residual degradation rate and pesticide species in the crop. Washing, blanching, and drying processes can reduce chlorpyrifos, fenvalerate, and cypermethrin residues in spinach, and reduce dietary exposure; freeze-drying and hot-air drying are related to the loss of pesticide residues in spinach. The solubility of pesticides is related to vapor pressure. The loss rate of thionin in hot air drying is more than 60%, while dimethoate has almost no loss in freeze-drying; therefore, processing companies should consider the type of pesticide used in spinach production according to the processing method.

3. To assess the theoretical maximum daily intake (TMDI) of pesticides in spinach in China and establish limit standards. Dietary exposure assessment of pesticides is the basis for risk management and the establishment of limit indicators. The TMDI assessment method was used to calculate the dietary risk index (% ADI) of 14 pesticides in Chinese spinach standards. The results showed that the risk index of pyrethroid pesticides was low. (12.2% 48.7%), while the organophosphorus pesticides have a high risk index; the dimethoate and diazinon risk indices are 243.6% and 121.8%, respectively, and further corrective measures should be taken to reduce the risk index. Different limit formulation methods are used to arrive at different pesticide residue limits and safety intervals; the EU's set-up method is consistent with the actual production and the most stringent, chlorpyrifos, beta cypermethrin, malathion, metalaxyl and premphovir pesticides. In spinach, MRLs in raw spinach were 1, 0.5, 0.1, 0.1, and 0.5 mg kg-1 for spinach, and the safety intervals were 7, 7, 3, 14 and 14 days, respectively. For the first time, the processing factors of pesticides in spinach were used to set the pesticide MRL in dehydrated spinach, and the dehydration was set according to the processing factors of chlorpyrifos, cypermethrin, fenvalerate, and malathion in spinach products, combined with the MRL in the raw materials. The MRLs in spinach were 5, 6, 3 and 3 mg kg-1, respectively. Fourth, China's spinach and its products in the formulation and control of pesticide residue limit recommendations. The control of pesticide residues in spinach and the formulation of indicators should be controlled throughout the process under consistent, continuous, and effective monitoring conditions. Indicators and indicator values ​​at different stages should be uniformly set rules; the establishment and execution of limits should be based on risk assessment, and Combining actual production and pesticide registration requirements; control of pesticide residues in spinach requires multiple inputs, and improves and straightens out relevant laws and regulations. This study has positive theoretical and practical significance for the control of pesticide residues in China's spinach export, formulation of limit indicators, and dietary exposure assessment for consumers. It also has implications for the setting of pesticide limit indicators in related processed agricultural products.

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