Abstract: Liquid milk aseptic brick packaging is the current high-end packaging form of liquid milk, which can effectively protect liquid milk from internal fats and protein and other nutrients within a long shelf life. Its key performance is whether the oxygen transmission rate is appropriate, that is, oxygen-barrier The lower the oxygen permeability and the higher the oxygen barrier, the more effective oxygen permeability test equipment must be used for effective monitoring of aseptic brick packaging materials to ensure longer shelf life requirements for aseptic bricks. This article describes in detail the detection principle and method of oxygen permeability of liquid milk aseptic brick packaging, and provides technical and data guidance for relevant industries.

Keywords: liquid milk, sterile brick, oxygen permeability, oxygen barrier, barrier, deterioration, shelf life, oxygen permeability test system

Test significance:

Liquid milk is a common product in dairy products. It has a high content of fat and protein, contains many kinds of amino acids and a lot of fat-soluble vitamins, and is easily digested and absorbed by the body. It is the best natural food. In order to ensure that this perfect food is convenient for the public to carry daily food, the packaging of liquid milk is mainly compact and easy to open. At the same time, in order to ensure its taste and nutritional content to the greatest extent, packaging materials used in liquid milk should also have good barrier properties. In particular, it should have high barrier to oxygen in the outside air. At present, aseptic brick is a high-end packaging form of liquid milk that is commonly used in developed countries. It is a paper aluminum-plastic packaging made of polyethylene, paper, aluminum foil, etc., as a substrate for food-specific cardboard. Domestic commonly used sterile bricks, beneficial bricks and combiboxes, are filled with liquid milk using ultra-high temperature instantaneous sterilizing technology, and then liquid milk filling and aseptic brick sealing under aseptic conditions.

Liquid milk packed in aseptic brick can meet the requirement of room temperature shelf life of 180 days without adding preservatives , even some aseptic bricks with high barrier property can reach 8 months, which mainly depends on the use of sterile bricks. How is the oxygen barrier property of the packaging material? However, in the process of using liquid milk aseptic bricks, the oxygen block resistance of aseptic brick packing materials often deviates or fails to meet expectations, and quality problems such as deterioration of liquid milk within the shelf life period occur. Therefore, the oxygen transmission rate should be used as a key monitoring performance indicator for a manufacturer of aseptic brick liquid milk. The lower the oxygen transmission rate value, the better the oxygen barrier property of the material and the liquid milk will not be easily oxidized or deteriorated during the shelf life. Long shelf life requirements. This article uses a professional oxygen permeability testing device that can test high barrier packaging materials to test the oxygen permeability of aseptic brick packaging samples, providing technical and data reference for related industries.

Detection method:

Oxygen barrier test methods for soft plastic packaging are divided into equal pressure method and differential pressure method. The isostatic method absorbs oxygen through the sample through an internal Coulomb electricity sensor. Each oxygen molecule releases four electrons and utilizes oxygen molecules. The linearly proportional relationship between the quantity and the number of electrons calculates the oxygen transmission rate. This process is not affected by the osmotic concentration and changes in the sensor environment. Due to the high output efficiency of Coulomb's power sensor and its low detection limit, it can accurately test the oxygen transmission rate of high-barrier materials. Isobaric methods can be used to overcome the unavoidable impact of differential pressure on plastic containers due to pressure differentials and to extend the use of containers for testing.

At present, the domestic isobaric test oxygen permeability test follows the national standard of GB/T 19789-2005 “ Coulomb Test Method for Testing Plastic Film and Sheet Oxygen Permeability of Packaging Materials ”. We will use the OX2/230 Oxygen Permeability Test System independently developed by Labthink and combined with this standard to perform oxygen permeability tests on aseptic brick packaging samples.

1 , test equipment

OX2/230 Oxygen Permeability Test System ( Labthink ) with ultra-high precision, independent three-cavity structure can test three identical or different samples at the same time, the temperature control range is 15 °C ~ 55 °C , and the humidity control range is 0%RH , 35%RH ~ 90%RH , film oxygen permeability test range (0.01 ~ 6,500) cm3/m2 · 24h , and can be extended to (0.07 ~ 6,5000) cm3/m2 · 24h . This system can also be extended to test Oxygen Transmittance Ranges from 0.0001 to 60 cm3/(pkg·d) containers. System 10 may be implemented instruments are connected in parallel, an efficient system of 30 samples tested simultaneously.

The instrument satisfies ISO 15105-2, GB / T 19789, ASTM D3985, ASTM F2622, ASTM F1307, ASTM F1927, JIS K7126-2, YBB 00082003 a number of national and international standards, can meet a variety of different soft plastic temperature and humidity environment Film, paper-plastic composite film, co-extruded film, aluminized film, aluminum foil, aluminum foil composite film and other film materials and various materials sheet oxygen barrier test, and can expand the test made of various materials bottles, bags, cans Oxygen permeability test for boxes, boxes and barrels.

Figure 1 OX2/230 oxygen transmission rate test system

2. Preparation of sample

The aseptic brick samples were placed in a 23 °C environment and placed in a desiccator for 48 hours. After removal, the samples were cut from each sample taken diameter of 108 × 108 mm 3.

3. Test conditions

Venue: Jinan Languang Packaging Safety Testing Center Test Temperature and Humidity: 23°C, 0% RH
Test method: Isobaric method (coulomb power sensor method)

4. Test procedure

4.1 Test principle

OX2/230 uses the isobaric test principle. The pre-treated sample is clamped between the test chambers. Oxygen flows on one side of the membrane and high-purity nitrogen flows on the other side of the membrane. The oxygen molecules diffuse through the membrane to the high purity nitrogen in the other side and are carried by the flowing nitrogen to the sensor. By analyzing the concentration of oxygen received by the sensor, parameters such as oxygen permeability are calculated. For packaging containers, high-purity nitrogen flows in the container, and air or high-purity oxygen surrounds the outside of the container.

4.2 sample clamp

A layer of vacuum grease is applied to the edge of the convex outer edge of the ventilated outdoor surface to prevent grease from depositing on the cavity intermediate disc. The vacuum grease on a sample cut from the same taken three state regulator has completed samples were clamped in OX2 / 230 oxygen transmission rate test system 3 coated the surface of the outdoor air-permeable, the sample to avoid wrinkles, light Light press makes good contact with vacuum grease. Cover the breather cover and fasten and seal it.

4.3 Detection process

OX2/230 is a highly intelligent detection device. The test process is convenient and easy to operate:

Three oxygen transmission Aseptic packaging material samples were 0.2004 cm3 / m2 · 24h, 0.1908 cm3 / m2 · 24h, 0.2127, the relative average deviation between test results for each sample were lower than the samples 3 10% . Therefore, the oxygen transmission rate of the tested liquid milk aseptic brick packaging material can meet the barrier requirement of liquid milk within the shelf life of 6 months.

to sum up:

The OX2/230 Oxygen Permeability Test System monitors oxygen barrier properties of liquid milk sterile bricks to obtain repeatable and reproducible oxygen permeability results that accurately reflect the barrier properties of aseptic brick packaging materials. The test equipment and test standards used in this test are also applicable to the oxygen permeability test of soft plastic composite film materials for other uses, such as aluminum powder plastic film and packaging of meat products. Labthink has been committed to providing professional testing services and equipment for customers around the world. Over the years, it has provided tens of thousands of barrier testing services to customers around the world, providing customers with reliable data support. For more information about related testing instruments, you can visit the website of Jinan Languang Company to view specific information or call us directly. Labthink expects to enhance the technical exchanges and cooperation with enterprises and institutions in the industry.

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