Perspective on the performance indicators of the s

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Milk packaging: Perspective on performance indicators of safe packaging

among all nutritional sources, big milk, as a complete food, can provide most of the nutrients required for human growth and development. Therefore, as one of the best foods, it is widely eaten all over the world. Big milk is extremely nutritious, so it is also very easy to deteriorate and decay. In order to keep fresh in the circulation process and provide it to consumers safely and healthily, milk must be packaged safely. Our performance requirements for milk packaging include:

safety and health indicators for large milk packaging

as milk is for people to eat, packaging materials, printing inks, composite adhesives, blow molding particles and additives must meet the food hygiene standards of packaging materials and the requirements of food packaging regulations, Non toxic, odorless, odorless, less residual solvents, no toxic heavy metals, etc

safe and non-toxic

various additives, such as antioxidants, antistatic agents, and smoothing agents, need to be added in the process of plastic film processing and molding. All processing aids, color masterbatch particles, raw material particles, inks, adhesives, solvents, etc. must pass the test and detection of gb15193 food safety toxicology evaluation procedure, and can only be used after being proved safe and non-toxic through acute toxicity test and chronic toxicity test

meet the national food hygiene standards for packaging materials

there are many national hygiene standards for food packaging materials, including raw materials, processing aids and molded products. In the hygienic standards for molded products, commonly used ones are: polyethylene packaging material gb9687; Polypropylene packaging material gb9688; Polystyrene plastic cup gb9689; Polyester plastic bottle gb13113; Paper gb11680; Composite bag gb9683, etc. In liquid milk packaging, generally, single-layer or three-layer coextrusion black-and-white bags must meet gb9687, while EVOH five layer coextrusion black-and-white bags, PVDC coated three-layer coextrusion black-and-white bags, PVA composite bags, paper-based composite packaging materials, etc. are recommended to meet gb9683, and its coextrusion blow molding layer PE must meet gb9687. The difference between gb9683 and gb9687 mainly lies in the content of toluene diamine and the amount of n-hexane evaporation residue. The content of toluene diamine is aimed at the adhesive in composite bags. Toluene diamine is a carcinogen. The amount of n-hexane evaporation residue is not more than 60mg/l in gb9687 hygienic standard for polyethylene molded products, and not more than 30mg/l in gb9683 hygienic standard for composite packaging bags. This index mainly simulates the dissolution of food packaging materials in oil immersion solution. If the production enterprise controls it improperly, it is very easy to exceed the standard. During the gb9683 test, the soaking conditions and nominal capacity must be strictly stipulated to ensure the scientificity and impartiality of the test results. The soaking condition of packaging bags with sterilization temperature higher than 60 ℃ is 120 ℃ for 40min, and that of others is 60 ℃ for 2hr; It is appropriate to make it into the actual size of the packaging bag and soak it on the inner surface. If the whole packaging material is soaked, it will not only soak the inner and outer surfaces, including printing ink, but also its nominal capacity cannot be accurately calculated

specify the amount of residual solvent

general dairy packaging bags need to go through printing, compounding, blow molding and other processing procedures, while printing ink and composite adhesive contain a certain amount of solvent. In production, some solvents need to be added to adjust the printing suitability and dilute the adhesive to facilitate coating and other functions. As processing aids, the solvent must meet the requirements of gb9685 hygienic standards for the use of additives for food containers and packaging materials, and alcohol or ketone solvents must be used. For food packaging, the requirements for odor and potential toxicity are more and more strict, and the lower the solvent residue is required, the better. The national standard stipulates that the total residual solvent is less than 10mg/m2, and the residual benzene and ester solvents are less than 3mg/m2. The reason of the enterprise standard is not complicated. It can be higher than the national standard that the total amount is less than 5mg/m2, and the residues of benzene and esters are less than 2mg/m2

microbiological testing

for different production processes, reduce noise, vibration and harshness (NVH) loading methods, storage conditions, contents, shelf life, etc., and specify different microbiological testing indicators. GB plastic composite films and bags for liquid food packaging (implemented since December 2005) stipulates that the total number of bacteria in ordinary plastic bags is less than 1/cm2, and the total number of bacteria in sterile bags is less than 5/cm2, and pathogenic bacteria shall not be detected. In order to facilitate the detection, general enterprises will stipulate that each packaging bag, bottle or box is the detection unit, the total number of bacteria is less than 5, and Escherichia coli, yeast, mold, pathogenic bacteria, etc. shall not be detected

milk safety performance requirements

in order to meet the requirements of high-speed automatic milk filling machine, the milk packaging film must meet the following performance requirements during production:

smoothness performance

the inner and outer surfaces of the film should have good smoothness to ensure that it can be carried out smoothly on the high-speed automatic filling machine. Therefore, the friction coefficient of the inner and outer surfaces of the film is generally required to be 0 4, and external/external friction coefficient internal/internal friction coefficient. The smoothness of the film is mainly achieved by adding a smoothing agent to the raw materials. The smoothing agent is usually oleic acid amide or erucic acid amide, or high molecular inorganic compound. It is only physically mixed with polymer polyethylene and cannot be well compatible. The molecular thermal movement makes it gradually migrate to the surface and accumulate into a uniform thin layer, which can significantly reduce the friction coefficient of the film and make the film have a good smooth effect. However, the amount of smoothing agent added to the milk film must be strictly controlled. On the premise of ensuring automatic filling, it cannot be too much. Too much smoothing agent will migrate to the surface of the film, which will affect the printability of the film and reduce the adhesion fastness and heat sealing strength of the ink. The dosage of smoothing agent should be adjusted according to the equipment, production process, filling requirements, external environment, contents and shelf life requirements. It is recommended that the raw material PE use particles without smoothing agent. In addition, the choice of the type of smoothing agent is very important, which will affect the odor of the milk film

tensile property

as the plastic film will be subjected to the mechanical tension from the automatic filling machine during the filling process, it is required that the film must have sufficient tensile strength to prevent deformation or breakage under the tension of the automatic filling machine. LLDPE or HDPE with good tensile strength can be selected in the film formula to improve the tensile strength

heat sealing performance

the most worrying thing about automatic film packaging is the bag breaking problems caused by leakage, false sealing, knife sticking, etc. the faster the filling speed is, the higher the heat sealing requirements are. Excellent heat sealing performance should include: high heat sealing strength to ensure that the seal will not be damaged during transportation; High thermal adhesive strength ensures the integrity of the sealing of the film during thermal cutting and filling; Wide heat sealing temperature range to ensure normal sealing within a certain temperature range caused by external factors; Good sealing property ensures that the film can be cut off smoothly during thermal cutting without wire drawing sticking; A certain degree of pollution resistance ensures that the seal still has a certain heat sealing strength when there are inclusions. Adding a certain proportion of LLDPE and mLLDPE to the film formula is of great help to improve the heat sealing performance, but too high content will affect the cutting effect

surface wetting tension

because polyethylene is a non-polar polymer material, its molecular structure does not contain polar groups, and its crystallinity is high, its surface free energy is low, its surface tension is small, its adhesion to ink is not ideal, and its printing suitability is poor. In addition, the continuous migration and precipitation of processing aids (low molecular substances such as smooth agents and opening agents) in the film to the surface will also affect the printing fastness of the ink. Therefore, before printing, it is generally necessary to corona treat the plastic film, change the chemical structure of the film surface, improve the surface tension of the film, and improve the adhesion of ink. It is generally required that the surface tension of polyethylene film should reach above 80%. In addition, on the automatic filling equipment, when the packaging materials are soaked or sprayed with hydrogen peroxide and extruded by the film feeding roller, if the printing fastness is not enough, the patterns are easy to fall off, wear or blister with hydrogen peroxide

barrier performance

packaging materials are required to have the functions of oxygen resistance, light resistance, moisture resistance, fragrance preservation and odor prevention. Barrier materials should be selected according to different contents, shelf life, production equipment, storage conditions, etc. On the one hand, it is necessary to ensure that bacteria, dust, gas, light, water, etc. in the external environment cannot enter the packaging bag; On the other hand, it is required that the packaging material itself has good stability, does not absorb odor, and small molecules are difficult to migrate; There is also to ensure that the moisture, oil, aromatic components and components essential to product quality contained in milk do not penetrate outward, so as to achieve the purpose of packaging food without deterioration

requirements for ink performance

milk packaging film is usually printed by surface printing. In addition to the general technical requirements of surface printing ink, such as adhesion, wear resistance and scratch resistance, as a liquid milk packaging, it must be able to withstand pasteurization or hydrogen peroxide sterilization and boiling treatment requirements. It is required that the ink must also have oxidation resistance, water resistance, heat resistance and freezing resistance, so as to ensure the production, circulation During transportation, storage and other links, ink will not fall off, flower, condensation and other phenomena

stability under high temperature

the stability of packaging bags directly affects the safety and hygiene of dairy products. Due to packaging materials, formulas, structures, processing aids, production processes, environmental conditions and other reasons, the decomposition, migration, adsorption and even chemical reaction of the active ingredients in the packaging bag with the contents, which will affect the quality of dairy products, such as peculiar smell, loss of milk flavor, stratification, changes in tissue structure and so on, and even cause human side effects in serious cases; Or the packaging bag is soaked in water or milk at a certain temperature, causing delamination, shrinkage, discoloration, adhesion and other phenomena. Special attention should be paid to high temperature and long-term storage in summer


with the increasing growth of China's economy and the rapid development of high-tech, the competition in the dairy industry is becoming increasingly fierce. Today's society is a society that pays attention to quality and technology, as well as safety and health. Guangming dairy not only brings safe, fresh and nutritious products to consumers, but also pays more attention to safe, hygienic and environmental friendly packaging materials. Therefore, the author believes that:


update the food hygiene standards of raw materials, processing aids and molded products as soon as possible. Most food hygiene standards were promulgated and implemented in 1988 with higher wages. Many application scope, physical and chemical indicators, testing items and so on do not meet the needs of industry development


carry out the compatibility test between food contents and packaging materials as soon as possible. The State Pharmaceutical Administration has standards for the compatibility test between drug packaging materials and drugs, but there is no corresponding national or industrial standard for food. The existing gb/t16265 packaging material test method

compatibility was issued in 1996 and is not applicable to milk plastic bag packaging. Food, especially liquid milk, is prone to the mutual migration or adsorption of packaging materials and milk, resulting in the peculiar smell and deterioration of milk. However, there is no unified standard for the detection of milk odor


enforce the detection of solvent residues in printing inks and composite adhesives; Specify the residual detection of monomer or other volatile gas impurities in polymer molding products; Specify the detection of soluble toxic impurities in printing ink

4 promulgate the national standard of composite film and bag for milk powder packaging as soon as possible

5 implement safety and environmental protection market access for food packaging materials

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