Milk powder aluminum foil composite packaging bag nitrogen or carbon dioxide gas permeation detection

2023-02-05 11:10:59

Abstract: As a high-fat, high-protein nutritious food, milk powder needs to be packaged and stored with high-barrier packaging materials such as aluminum foil composite packaging bags, and is often filled with nitrogen-filled packaging or modified atmosphere packaging to ensure an internal oxygen-free or low-oxygen environment. To prevent the milk powder from being oxidized and deteriorated. However, the barrier properties of the packaging materials to the nitrogen or carbon dioxide gas filled in the above packaging form require professional testing equipment and related testing methods to monitor, so as to ensure that the internal gas is not easily lost. This paper provides a technical reference for related industries by testing the nitrogen permeability and carbon dioxide transmission rate of aluminum foil composite film for milk powder .

Key words: milk powder, aluminum foil composite film, nitrogen-filled packaging, modified atmosphere packaging, nitrogen barrier, carbon dioxide barrier, nitrogen permeability, carbon dioxide transmission, oxygen-free or low-oxygen environment, differential pressure gas permeation meter

Test significance:

The powdered aluminum foil package is made of plastic and aluminum foil composite film as a packaging bag, which has high barrier to O 2 and H 2 O and good light blocking property. As a barrier layer in the middle of the composite film, aluminum foil has high barrier properties to O 2 , CO 2 , N 2 , air and H 2 O. Therefore, when the composite film containing aluminum foil is used as a milk powder package, it is at 23 ° C , 0%. The oxygen transmission rate (ie, oxygen barrier) in the standard environment of RH can reach 0.05 cm 3 /(m 2 ?24h?0.1MPa) , and the water vapor transmission rate (ie, resistance ) at 38 °C and 90% RH environment Wet) can reach 0.01 g / (m 2 ? 24h) . However, in order to extend the shelf life of the milk powder and ensure the sensory quality of the milk powder, the aluminum foil composite film bagged milk powder is often packaged in nitrogen-filled or modified atmosphere to meet the oxygen-free or low-oxygen storage environment of the milk powder.

The powdered nitrogen filling package or the modified atmosphere packaging is to put the milk powder into the packaging bag, and the air in the packaging bag is taken out to a predetermined degree of vacuum, and then filled with pure N 2 or a certain proportion of N 2 , CO 2 and the like, and then the sealing is completed. Process. The nitrogen-filled packaging makes the milk powder completely protected by the inert gas N 2 , which eliminates the oxidative deterioration reaction of the oxygen environment to the milk powder; and the CO 2 used in the modified atmosphere packaging is to make the milk powder in an acidic environment and inhibit the milk powder. most aerobic bacteria growth, which is the effect of 2 N 30-fold, and moisture within the package milk powder form liquid CO 2 is reacted with carbonate, such that the gas within the package is reduced, is formed slightly negative pressure, or to prevent the bag up up The phenomenon of the can occurs. However, if the nitrogen-filled package or the modified atmosphere package has poor barrier properties to N 2 or CO 2 , that is, a high nitrogen permeability or a high carbon dioxide transmission rate, the amount of gas inside the milk powder is large, and the milk powder is easy. Bacterial reproduction leads to quality problems such as oxidative deterioration. This paper selects a brand of aluminum foil composite film packaging bag in the form of air- conditioning, and tests the nitrogen permeability and carbon dioxide transmission rate under the standard environment of 23 °C and 0% RH to verify the barrier of the bag to internal N 2 or CO 2 . How to provide technical guidance for the quality of controlled packaging materials for dairy products manufacturers.

Detection method:

At present, the barrier test of N 2 or CO 2 in soft plastic packaging is only a principle method of differential pressure method. The corresponding differential pressure tester is to place the sample between the high and low pressure chambers and pump the low pressure chamber. Vacuum, fill the high pressure chamber with a certain pressure of N 2 (or CO 2 ), and test the nitrogen (or carbon dioxide) transmittance of the sample by testing the pressure change in the low pressure chamber. This method has a wide test range and is suitable for high barrier. The material is tested for low nitrogen (or carbon dioxide) transmission.

At present, the domestic differential pressure test gas permeability ( 23 °C standard test environment) test follows the national standard of GB 1038-2000 "Plastic film and sheet gas permeability test method pressure difference method". We will use the VAC-VBS differential pressure gas permeation instrument independently developed by Labthink to conduct nitrogen gas transmission rate and carbon dioxide transmission rate test on high barrier aluminum foil composite film packaging bags according to the above standard methods.

1 , test equipment

VAC-VBS differential pressure gas permeation instrument ( Labthink ), three-cavity average design, single test can test the average value of three samples, 15 °C ~ 55 °C controllable temperature range, test range 0.1 ~ 100,000 cm 3 / m 2 · 24h · 0.1MPa , the test chamber vacuum can meet the high level requirements of < 20 Pa . The instrument meets various national and international standards of ISO 15105-1 , ISO 2556 , GB/T 1038 , ASTM D1434 , JIS K7126-1 , YBB 00082003 , and can meet various plastic films, sheets and metal foils under different temperature environments. And different gas permeability tests of various high-barrier materials , such as inorganic gases or inert gases such as O 2 , N 2 , CO 2 , He .

2. Preparation of samples

The aluminum foil composite film package sample was placed in an environment of 23 ° C and placed in a desiccator for 48 hours. After removing the specimen, taken from the sample having a diameter of 97 mm cut sample 6, respectively, and the carbon dioxide permeability to the nitrogen permeability test, each gas tested using three samples required.

    3. Test environment

    Location: Jinan Languang Packaging Safety Testing Center Test Temperature and Humidity: 23 ° C, 0% RH
    Test gas: pure dry nitrogen, pure dry carbon dioxide gas test method: differential pressure method

    4. Test procedure

4.1 Test principle

The VAC-VBS adopts the differential pressure test principle, and the pre-treated sample is placed between the upper and lower test chambers and clamped. Open the test lower chamber valve, vacuum process the low pressure chamber (lower chamber), and then vacuum the whole system; when the specified vacuum degree is reached, close the test lower chamber and fill the high pressure chamber (upper chamber) with a certain pressure test. The gas forms a constant pressure difference (adjustable) on both sides of the sample; the gas penetrates from the high pressure side to the low pressure side under the action of the pressure difference gradient, and the gas of the sample is obtained by monitoring the pressure on the low pressure side. Transmittance.

4.2 sample clamping

Apply a layer of vacuum grease on the outer surface of the test chamber to prevent the grease from being applied to the cavity intermediate disk; after placing the filter paper on the disk in the test chamber, the three conditionally adjusted samples are respectively cut . Installed on the three test chambers of the VAC-VBS differential pressure gas permeation instrument , the sample should be kept flat, no wrinkles, lightly press the sample to make good contact with the vacuum grease, and then clamp the structure clamp with the test cavity. Tight sample.

4.3 Detection process

VAC-VBS is an automated test instrument, and the test process is convenient and easy to operate:

  • Connect the nitrogen gas source to the device port.
  • Set the parameters, adjust the test temperature to 23 °C , and adjust the relative humidity to 0% RH .
  • Open the device software, set the test parameters, and start the test. Test parameters include control parameters (test mode, upper chamber purge time, upper chamber pressure, test time, degassing time, etc.) and sample parameters (number, type, area, thickness, etc.).
  • End of test, data processing.
  • Turn off the air supply and power supply.
  • After the gas source was changed to carbon dioxide gas, the carbon dioxide transmittance of the sample was tested in accordance with the above method.

The nitrogen permeability and carbon dioxide permeability of the milk powder aluminum foil composite film bag sample at 23 °C and 0% RH test conditions were 0.0814 cm 3 /m 2 ·24h·0.1MPa and 0.9203 cm 3 /m 2 ·24h· 0.1MPa , the relative deviation of the test results of the three samples of each test is less than 10% .

to sum up:

The VAC-VBS differential pressure gas permeation instrument can obtain accurate test results when testing the nitrogen permeability and carbon dioxide permeability of aluminum foil composite film for milk powder, which helps dairy products manufacturers to monitor packaging materials for key gases. The barrier performance ensures product quality and safety. The testing instruments and testing methods mentioned in this paper are also applicable to soft plastic packaging materials of other materials for gas barrier tests such as O 2 , CO 2 , N 2 , and air . Labthink has been committed to providing professional testing services and equipment to customers around the world. Over the years, it has provided tens of thousands of gas barrier testing services to customers around the world, providing customers with reliable data reference. For more information about related testing instruments, you can visit Jinan Languang for specific information or call us directly. Labthink is looking forward to enhancing technical exchanges and cooperation with enterprises and institutions in the industry.

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