Requirements for coating on the inner wall of food

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Requirements for coating on the inner wall of export food packaging barrels

with the expansion of the definition of food safety, countries' requirements for the packaging of food and agricultural products continue to improve. In the international market, many food and agricultural products are packaged in steel drums, and the sanitary requirements of their inner wall coatings have aroused widespread concern in various countries. As early as the 1950s, the U.S. FDA required to attach great importance to the inspection of food and agricultural product packaging barrels. In order to meet the needs of the international market, China has also made specific provisions on the hygienic requirements for the coating on the inner wall of the packaging barrels of exported food and agricultural products

at present, the internal coated steel drums used to hold food and agricultural products in China generally include: Honey barrels, fruit juice barrels, tomato sauce barrels, etc. If the inner coating packaging barrel used to hold these foods fails to meet the hygienic requirements for safe food, it will cause secondary pollution to the food and affect the internal quality of the product

according to the regulations, the food grade coatings allowed to be used on the inner wall of the steel drum of the packaging barrel include polyamide epoxy resin coating, ethylene peroxide coating and organic fluorine coating

polyamide epoxy resin coating belongs to epoxy resin coating, and epoxy resin coating belongs to curing film-forming coating. Epoxy resin is generally polymerized from bisphenol A (bisphenol propane) and epichlorohydrin. According to the degree of polymerization, the molecular weight of epoxy resin is also different. From a health point of view, the greater the molecular weight (i.e., the smaller the epoxy value) and the more stable it can be stored, the less likely it is to dissolve harmful substances and migrate to food, so its safety is higher. Polyamide, as the curing agent of polyamide epoxy resin coating, is a kind of high molecular compound. There is no report on its toxicity. The quality of polyamide epoxy resin (epoxy value of epoxy resin) is closely related to the ratio of curing agent and curing degree. The proper proportion of curing agent and the higher the degree of curing, the less uncured substances in the epoxy resin coating migrate to food. According to GB hygienic standard for polyamide epoxy resin coating on inner wall of food containers, the evaporation residue of polyamide epoxy resin coating in various solvents shall be controlled below 30mg/L

the perchloroethylene coating uses perchloroethylene resin as raw material and plasticizer. After brushing or spraying the inner wall of the packaging barrel, it will naturally dry and form a film. Perchloroethylene coating is generally divided into primer and finish. Perchloroethylene resin contains vinyl chloride monomer. Vinyl chloride is a toxic compound that causes cancer. The perchloroethylene coating after film formation may still contain the residue of vinyl chloride. According to GB hygienic standard for perchloroethylene interior wall coating of food containers, the residue of vinyl chloride monomer in the perchloroethylene coating after film formation shall be controlled below 1 mg/kg. Plasticizers, solvents and other additives used in perchloroethylene coatings must comply with the relevant provisions of GB hygienic standard for the use of additives for food containers and packaging barrels. Toxic or highly toxic additives shall not be used. The coating shall be uniform without bubbles, spots, folds and falling off

organic fluoro coatings include polyfluoroethylene, polytetrafluoroethylene and polyhexafluoropropylene coatings. These coatings are polymerized with fluoroethylene, tetrafluoroethylene and hexafluoropropylene as the main raw materials in terms of composite fiber price, and are sprayed on the inner wall surface of the packaging barrel with certain additives. Organic fluorine coating has the characteristics of anti adhesion and corrosion resistance, but its acid resistance is poor, so it is widely used in the steel barrel of the inner coating packaging barrel containing honey. In terms of application, the organic fluorine coating on the inner honey packaging barrel and steel barrel is polytetrafluoroethylene, referred to as PVF coating for short. It is a high molecular compound with stable chemical properties. Generally, there will be no monomer residue. It is a relatively safe coating for the inner wall of food packaging barrels. However, when cleaning the inner wall of the steel drum of the packaging drum, most of the packaging drum manufacturers currently use the spray cleaning and drying line for cleaning. Chromate is commonly used as cleaning agent, which may cause the chromate to remain on the surface of the container and then mix into the internal coating

therefore, when producing steel barrels coated with honey, the steel barrels coated with honey should be inspected in accordance with GB hygienic standard for polytetrafluoroethylene coating on the inner wall of food containers. The standard stipulates that the appropriate amount of chromium and fluorine shall be controlled between 0.01 mg/L and 0.2 mg/L respectively. In addition, when baking Teflon, if the temperature reaches 280 ℃, it will split and produce highly volatile toxic fluoride. Therefore, when using Teflon coated with honey packaging barrel steel barrel, the general baking temperature shall not exceed 250 ℃

in recent years, fruit juices, ketchup and honey exported by China have often been returned abroad due to excessive pesticide content. As a food packaging barrel, the residue of coating solvent on its inner wall should be as low as possible. Therefore, in the production of food inner coated packaging barrels, it must be in accordance with the food safety and health requirements to ensure that the cleanliness of food packaging barrels and the content of residual harmful substances do not exceed the requirements of the health standards. To this end, a linked supervision system should be formed. The enterprises using food packaging barrels should increase by 51% year-on-year to ask the packaging barrel manufacturer for the food safety and hygiene inspection report of the packaging barrel; The packaging barrel manufacturer shall ask the coating supplier for the food safety and hygiene inspection report of the inner wall coating. At the same time, relevant departments shall also regularly supervise and inspect food packaging barrels and issue inspection reports

source: Guomen times


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