Effects of food storage and processing on pesticide and veterinary drug residues

作者：admin  点击次数：20  发布时间：2025-04-12

1. Storage
During storage, the pesticide residues in grains decrease slowly, but some pesticides can gradually penetrate into the grains, causing the residues inside the grains to increase. When vegetables and fruits are stored at low temperatures, the pesticide residues decrease very slowly. For example, after 3 months of storage at 0-1°C, the residues of most pesticides decrease by less than 20%. Storage temperature has a great influence on the residues of volatile pesticides. For example, thiocarb is very stable at -10°C, but evaporates quickly at 4-5°C. The residues of volatile pesticides such as dichlorvos decrease more rapidly at higher temperatures. However, the pesticides remaining on the fruit skin also tend to penetrate into the flesh during storage.
2. Processing
Common food processing processes can generally reduce the pesticide residues to varying degrees, but under special circumstances, they can also concentrate, redistribute, or generate more toxic substances.
(1) Washing can remove most of the pesticide residues on the surface of crops. The degree of reduction in the residues is related to the number of days after application. Those with high polarity and high water solubility are easy to remove; washing with hot water, alkaline water, detergent, blanching, etc. can more effectively reduce the amount of pesticide residues.
(2) Shelling, peeling, grinding, and cleaning can usually remove most pesticide residues. After grains are milled and the husks are removed, the amount of most pesticide residues can be reduced by 70% to 99%. Systemic pesticides are not significantly reduced after such treatment. For example, after peeling potatoes, the amount of methyl parathion and ethyl parathion is reduced by 50% and 35% respectively, while non-systemic chlorpyrifos and malathion can be almost completely removed. Pesticide residues can also be greatly reduced after cleaning (picking) vegetables, but attention should be paid to the problem of pesticide residues in animal food caused by the use of removed outer leaves as feed. (3) Fruit processing The impact on pesticide residues depends on the processing technology and the nature of the pesticide. Jams, dried fruits, and preserved fruits processed with skin have higher pesticide residues, while the residues in juice are generally lower, but the content in fruit is higher. (4) Crushing, mixing, and stirring The enzymes and acids released by tissue and cell destruction can increase pesticide metabolism and degradation, but can also produce highly toxic metabolites.
(5) The degree of reduction in canned pesticide residues is mainly affected by the thermal stability of the pesticides. For example, parathion can only be reduced by 13% to 14%, while malathion can be almost completely destroyed.
(6) Oil processing Highly fat-soluble pesticides can enter oils in large quantities. For example, the concentration of parathion in orange oil is 100 to 300 times that of citrus as a whole. Vegetable oil refining processes, especially deodorization, can reduce pesticide residues to varying degrees. For example, the residues of pesticides such as lindane, DDT, dichlorvos, malathion, and chlorpyrifos can be reduced by 70% to 100%.
(7) Fermented beer The raw materials for beer production, such as barley and hops, often contain residues of pesticides such as glyphosate, but the filtration, dilution, and clarification processes in the production process can remove most of the pesticides, so the pesticide residues in beer are relatively low. Because there is no dilution process in wine production, the pesticide residue is relatively high, especially for red wine fermented with skins.
(8) Cooking is related to the nature of the pesticide, time, temperature, water loss, and airtightness. For example, 85% to 98% of white fungus can be volatilized during open cooking, while 50% is hydrolyzed into the soup during closed cooking. The pesticide residue in vegetables can be reduced by 15% to 70% after cooking, and rice, baking bread, etc. can also reduce the pesticide residue to varying degrees. Unlike pesticide residues, most veterinary drug residues in food cannot be effectively removed through processing, production, heating, and cooking. (V) Measures to control the amount of pesticide and veterinary drug residues in food
1. Strengthen the management of pesticide and veterinary drug production and operation
Many countries have strict pesticide management and registration systems. For example, the Federal Government Environmental Protection Agency is responsible for registering and approving pesticides in the United States, and the Ministry of Agriculture is responsible in Japan. In my country, the agricultural administrative department of the State Council is responsible for the registration and supervision of pesticides nationwide, and the pesticide testing agency under the agricultural administrative department of the State Council is responsible for the specific registration of pesticides nationwide. Application for pesticide registration requires the submission of pesticide samples and information on the chemistry, toxicology, efficacy, residues, environmental impact, labeling, etc. of the pesticides. After the application materials are reviewed and signed by the State Council’s agricultural, chemical industry, health, environmental protection departments and the National Supply and Marketing Cooperatives, they will be comprehensively evaluated by the Pesticide Registration Review Committee. Those who meet the requirements will be issued a pesticide registration certificate by the State Council’s agricultural administrative department.
my country has promulgated "GB15670-1995 Toxicological Test Methods for Pesticide Registration" and "GB15193-2003 Food Safety Toxicological Evaluation Procedures", which specifically stipulate and explain the toxicity test methods and result evaluation of pesticides and pesticide residues in food.
In 2004, the State Council promulgated the "Regulations on Veterinary Drug Management", which made clear provisions on the research, production, operation, import and export, use and supervision and management of veterinary drugs. The "Quality Management Standards for Veterinary Drug Production" formulated by the Ministry of Agriculture on this basis is the basic principle for veterinary drug production and quality management. In addition, the "Regulations on the Administration of Feed and Feed Additives" promulgated by the State Council in 1999 and revised in 2001 also made corresponding provisions for the management of feed additives, and these regulations should be strictly enforced.
2. Safe and reasonable use of pesticides and veterinary drugs
my country has promulgated the "GB4285-1989 Pesticide Safety Use Standard" and the "GB8321--1987 Pesticide Rational Use Guidelines", which stipulate the maximum dosage or minimum dilution multiple, the maximum number of uses and the safe interval (the number of days from the last application to the harvest period) for major crops and commonly used pesticides to ensure that the pesticide residues in food do not exceed the maximum allowable limit standard. At the same time, attention should also be paid to the publicity and guidance of farmers, strengthen safety protection work, and prevent pesticide pollution and agricultural poisoning accidents.
The publicity and guidance of the rational use of veterinary drugs should also be strengthened for livestock and poultry farmers, and the arbitrary use of veterinary drugs should be prohibited. The relevant regulations on the dosage and withdrawal period (withdrawal period before slaughter) of the permitted veterinary drugs must also be strictly observed to prevent the harm of veterinary drug residues in animal food to the human body.
3. Formulate and strictly implement the standards for pesticide and veterinary drug residue limits in food. By 1999, my country had formulated residue limit standards for 126 pesticides (34 of which were reviewed and approved but not officially issued). The "Standards for Maximum Residue Limits of Pesticides in Food" (GB2763-2005), revised in 2005, included the maximum residue limits (MRLS) for 136 pesticides, and dozens of pesticide residue analysis methods have been formulated. In addition, the "Maximum Residue Limits of Veterinary Drugs in Animal Foods", first promulgated by the Ministry of Agriculture of my country in 1997 and revised in 1999, stipulates the residue limits of veterinary drugs in cattle, sheep, pigs, poultry, horses, and fish. Internationally, the joint FAO/WHO meeting on pesticide residues (JMPR) evaluates pesticides with comprehensive toxicity and related data every year and formulates ADIs. The Pesticide Residues Subcommittee (CCPR) under the FAO/WHO Codex Alimentarius Commission (CAC) has formulated the maximum residue limits (MRLS) of pesticides in various foods on this basis. By 2004, CCPR had formulated 2,374 maximum residue limits for 197 pesticides in 289 foods and re-residue limits for 148 pesticides ("re-residue" refers to the pollution of food caused by pesticides that are stable, not easy to destroy, and can not disappear immediately from the polluted environment due to prohibition, but can exist in the soil and environment for a long time). CCRR not only formulates the maximum limit standards for various pesticide residues, but also provides actual residue determination data and toxicological data, and stipulates the recommended sampling methods, standard analysis methods and laboratory operating procedures for pesticide residue analysis, forming a relatively complete standard system for pesticide residue limits in food. The Codex Committee on Residues of Veterinary Drugs in Foods (CCRVDF) has also done a lot of work in formulating the maximum residue limits of veterinary drugs.
4. Formulate a pesticide and veterinary drug policy suitable for my country, develop new varieties with high efficiency, low toxicity and low residue, timely eliminate or stop using varieties with high toxicity, high residue and long-term environmental pollution, promote advanced application technology and spray equipment, vigorously promote the integrated prevention and control of crop diseases and insect pests, rectify the pollution caused by the production and use of pesticides to the environment, do a good job in the selection and popularization of high-quality poultry breeds, and actively promote the integrated prevention and control of animal diseases.