Oxygen Barrier Property Test Solution of Black and White PE Film for Liquid Milk

Liquid milk is an important part of many people’s diet. Since a large amount of fat and protein are contained in milk, it is easily oxidized and, as a result, the quality of the milk can be compromised within its shelf life. A main cause of oxidation is potentially thepoor oxygen barrier property of the packaging materials used for liquid milk. Therefore,it is necessary to perform oxygen permeability tests with a suitable instrument to evaluate whether the film or bag has adequate oxygen barrier properties.

Currently coextruded black and white film made of PE is widely used in package for liquid milk. Such material featuresopaque, low cost, portability and environment-friendly characteristics, for which it is popular in packaging for liquid milk. The barrier property of some black and white film is quite ordinary and the shelf life of the milk using such material is usually about 30 days. In contrast, when a material with ultra-barrier property is used as the packaging material for liquid milk, the shelf life can be extended to 90 days. Therefore, it is recommended that milk manufacturers to select suitable packaging materials by testing their oxygen permeability with testing instrument.

There are two methods for oxygen permeability test. They are the differential pressure method and the equal pressure method. The former will be elaborated in this article.

With differential pressure method, the sample is mounted in a gas transmission cell so as to form a sealed semi-barrier between two chambers. One chamber contains the test gas at a specific high pressure, and the other chamber, at a lower pressure, receives the oxygen. The oxygen will be detected by either a manometric sensor or a volumetric sensor. 

Labthink VAC-V2 Gas Permeability Tester adopts differential pressure method, which is used as the testing instrument to test the oxygen transmission rate of the black and white PE film specimens in the tests mentioned hereinafter.

The tests can be performed according to the following procedures.

1)    Condition the black and white PE film samples in a desiccant container at 23℃ for 48 hours. Then cut 3 pieces of round specimens whose diameter should be 97mm.

2)    Mount the specimens in the test chamber and clamp the specimens tightly.

3)    Set test parameters including control parameters and specimen parameters.

4)    Start the test. The test humidity can be adjusted in testing process if necessary.

5)    The tests will be performed automatically and test results can be obtained when the tests are finished.

According to the test results, the manufacturer or user of black and white PE film can determine whether the packaging material can meet their requirements for liquid milk package.

For more details about VAC-V2 Gas Permeability Tester, please visit www.labthink.com

About Labthink Instruments Co., Ltd:

Labthink Instruments Co., Ltd is one leading supplier of packaging testing instruments, which is headquartered in Jinan, China and operated in Boston, U.S.A.