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Abstract: Most packed milk powders are packaged with plastic composite films, including composite films formed of plastic and plastic, and composite films formed between plastic and aluminum foil (or aluminized). The above-mentioned composite films are mostly produced by a dry compound method and are subjected to ink printing and other processes, so injectables and other harmful components may be introduced into raw materials such as inks, adhesives, and their corresponding organic solvents. These insoluble substances are acidic, alcoholic, and oily. In the environment, it is easily precipitated and transferred to milk powder, which will harm the health of consumers. Therefore, the content of harmful small molecules in the plastic composite film should be strictly monitored, that is, the evaporation residue content in the composite film should be monitored. This article describes in detail the process of monitoring evaporation residue and its detection principle in plastic composite film for milk powder packaging, and provides guidance for the key health performance monitoring programs for dairy related industries.
Keywords: milk powder, dairy products, plastic composite film, aluminum-plastic composite film, harmful substances, insoluble substances, evaporation residues, hygienic properties, evaporation residue constant weight meter, dry cooling, constant weight
Test significance:
Milk powder is mainly bagged and canned in two forms. Some canned milk powders are even sealed in bags before being placed in cans. The packaging materials used in bagged milk powder are mainly plastic composite film materials, including composite films between transparent plastics and plastics, and plastic composite films containing aluminum foil layers or aluminized films. Of the plastic composite film mainly dry composite production process, i.e., the adhesive means on each layer in the composite film in the dry state, is easy to uniformly coat the gluing special organic solvent dissolved in one base film The agent is dried in a drying tunnel to dry all the solvent in the adhesive, and the adhesive is melted in a heated state, and then another substrate film is affixed thereto, and then is produced after being cooled and aged. Plastic composite film production process with excellent performance.
Plastic raw materials, inks, adhesives, organic solvents, additives, and other raw materials will be introduced during the manufacture and printing of plastic composite films, and these raw materials are prone to insoluble harmful substances caused by high-temperature oxidation and cracking during artificial addition or film formation. , And how to monitor these insoluble harmful substances, you need to immerse the composite membrane in water, acid, wine, oil simulation solution for a period of time, test the soaking solution " evaporation residue " content. Evaporation Residue This test can prevent and control the migration of these substances into the food content and endanger the health of consumers. In this paper, the aluminum foil laminated plastic composite film (abbreviated as aluminum-plastic composite film) is taken as an example, combined with the newly developed ERT-01 Evaporative Residue Constant Weight Tester by Jinan Languang Electromechanical Co., Ltd. to introduce the detailed testing process and principle of evaporation residue. Provides technical reference for the monitoring of health performance indicators for the dairy industry.
Figure 1 Packaging of plastic packaging for milk powder packaging
Detection method:
According to GB/T 5009.60-2003 “Methods for Analysis of Hygienic Standards for Polyethylene, Polystyrene, and Polypropylene Molded Products for Food Packaging,†the “ evaporation residue †test method was used to detect the evaporation residue in the plastic composite film for packaging milk powder.
Before the test, the samples were soaked in different solutions (water, 4% acetic acid, 65% ethanol, n-hexane) for 2 h at a specific temperature . The soaking solution was placed in a water bath and evaporated to dryness at about 100 °C . After drying for 2 h , cool and weigh. This indicator indicates the amount of dissolution in different soaking solutions. Different soaking liquids can simulate the contact with water, acid, wine, and oil with different properties.
This article will use the new ERT-01 Evaporative Residue Constant Weight Instrument independently developed by Labthink Languang Co., Ltd. in conjunction with the above standards to focus on the detection of the “ evaporation residue †index performance of aluminum-plastic composite film samples for milk powder packaging .
1 , test equipment
ERT-01 Evaporation Residue Constant Weight Meter ( Labthink Languang ):
Can test 0 ~ 80 g residue quality, test accuracy 0.3 mg ; temperature control range 100 ~ 130 °C , temperature control accuracy ± 0.2 °C ; hot air circulation speed 0.2 m / s , sample volume 0 ~ 200 mL ; stand-alone eight samples Independent testing and automatic test process greatly improve the detection efficiency. Using automatic lifting mechanism design and intermittent weighing measurement method to effectively reduce system error; test chamber hot air circulation system, automatic temperature control and dehumidification unique design; can be directly weighed under high temperature conditions to avoid the impact of human factors, Guarantee the accuracy of the test results; three test modes of proportion, blur, and difference meet the different testing needs of the user; with the user-friendly operation interface and intelligent data processing function of the operating software, you can connect LystemTM laboratory data sharing System, unified management of test results and test reports.The instrument meets a variety of national standards: GB/T 5009.60-2003 , GB/T 5009.64-2003 , GB/T 5009.68-2003 , GB/T 5009.69-2008 , GB/T 5009.203-2003 , GB/T 9740-2008 . It can be applied to various food utensils, containers, food packaging films, cans or other food tools, pipelines and other products made of polyethylene, polystyrene, polypropylene, and perchloroethylene resins as raw materials. The amount of dissolution in the measurement.
Figure 2 ERT-01 Evaporation Residue Constant Mass Meter
2. Preparation of sample
According to the contact area of ​​the sample, add 2 mL of liquid per square centimeter into the soaking solution. Soak in the following four solutions:
Water: 60 °C , soaking 2h ;
Acetic acid (4%) : 60 °C , soaking 2h ;
Ethanol (65%) : room temperature, soaking 2h ;
Hexane: room temperature, soak 2h .
3. Test conditions
Venue: Jinan Languang Packing Safety Testing Center Test Conditions: Laboratory Environmental Test Method: Evaporation Residue Meter Drying, Weighing
4. Test procedure
4.1 Test principle
After immersing the sample in different simulated liquids, a certain amount of soaking liquid shall be taken and placed in a constant-volume evaporating dish which has been dried in a high-temperature oven beforehand, evaporated on a water bath, cooled and weighed after drying at high temperature, and then continue drying and cooling. Weigh until constant weight. The mass minus the quality of the empty dish is the mass of the evaporation residue. Evaporation residues can effectively represent the total content of insoluble substances in packaging materials during the course of use in the presence of acids, wines, oils and other liquids of different nature.
4.2 Test procedure
The ERT-01 Evaporation Residue Constant Weight Meter converts the complicated steps of drying, cooling, constant weight, etc. originally required by water baths, ovens, dryers, and electronic instruments to a one-time completion of an intelligent detection instrument. , The operation is convenient, the result is accurate:
Take 200 mL of the sample soaking solution in n-hexane and divide it several times into a 50 mL glass evaporating dish that has been dried at a constant temperature of 100 °C ± 5 °C, and evaporate it on a water bath. The evaporation residue detector is set with test parameters, including temperature, weighing interval, test mode, and the like. Evaporate the evaporated evaporating dish into the evaporation residue instrument, and the instrument will complete the drying and constant weighing of the evaporating dish. At the same time, the blank soaking solution without the sample is dried and weighed at the same time according to the above steps. The quality of the evaporation residue and its content are calculated by the instrument software. Turn off the software program and instrument power. According to the above steps, the evaporation residue of the sample in water, ethanol and acetic acid soaking solution was tested separately. 
Figure 3 Drying process of the evaporating dish in ERT-01
The evaporative residue content of aluminum-plastic composite film samples for milk powder packaging in n-hexane was 15.7 mg/L and 14.9 mg/L , respectively. The difference between the results of the two parallel tests was 5.2% of the arithmetic mean value , which was completely satisfactory. 10% precision calculation requirements. The mean values ​​of the evaporation residues of the sample in water, ethanol and acetic acid soaking solutions were 7.4 mg/L , 16.8 mg/L , and 10.2 mg/L , respectively, which all met the precision requirements of the index test method.
to sum up:
The ERT-01 Evaporation Residue Constant Weight Meter not only reduces the waste of resources caused by various instruments required for previous evaporative residue tests, but also simplifies the complicated test procedures of drying, cooling, and constant weight, while ensuring convenience and convenience. Achieve better data stability and precision requirements. In the face of high frequency monitoring of the hygienic performance of packaging materials, the Evaporative Residue Constant Weight Meter can prevent the migration of harmful substances into food in a timely manner and prevent it from harming the health of consumers. The plastic composite film for milk powder packaging is just a typical representative of various packaging materials. For example, evaporation residue testing of other composite membranes, interior wall coatings, containers, etc. can be verified by this testing instrument. Labthink has been committed to providing customers around the world of professional, convenient and intelligent testing services and equipment, packaging material involving test indicators barrier properties, mechanical strength, health performance, you can visit our website to view blue light specific product information Or call for advice. Labthink expects to enhance technical exchanges and cooperation with users in various industries.
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