Abstract: Liquid milk aseptic brick packaging is a high-end packaging form of liquid milk. It can effectively protect nutrients such as fat and protein in liquid milk during a long shelf life. The key performance is whether the oxygen transmission rate is suitable, that is, oxygen barrier. High and low, the lower the oxygen transmission rate, the better the oxygen barrier property. Therefore, it is necessary to use an effective oxygen transmission rate test equipment to effectively monitor the aseptic brick packaging material to ensure the long shelf life requirement of the aseptic brick. This paper introduces in detail the detection principle and method of oxygen transmission rate of liquid milk aseptic brick packaging, and provides technical and data guidance for related industries.
Key words: liquid milk, sterile brick, oxygen transmission rate, oxygen barrier, barrier property, deterioration, shelf life, oxygen transmission rate test system
Test significance:
Liquid milk is a common variety in dairy products. It has high fat and protein content, contains various amino acids and a large amount of fat-soluble vitamins, and is easily digested and absorbed by the human body. It is a natural food of Zui. In order to ensure that this perfect food is convenient for the general public to carry and consume, the packaging form of liquid milk is mainly small and easy to open, and at the same time, in order to ensure the taste and nutrient composition to a large extent, the packaging materials used for liquid milk should also have good barrier. Sex, especially for oxygen in the outside air, should have high barrier properties. At present, aseptic brick is a high-end packaging form of liquid milk commonly used in developed countries. It is a paper-aluminum-plastic packaging made of polyethylene, paper, aluminum foil and the like. The common sterile bricks in China are the beneficial bricks and the combi box. The liquid milk filled in the system is subjected to ultra-high temperature instant sterilization technology, and then liquid milk filling and aseptic brick sealing are performed under aseptic conditions.
Liquid milk packed in aseptic bricks can meet the requirement of 180 days of normal temperature shelf life without the addition of preservatives . Even some aseptic bricks with higher barrier properties can reach 8 months, which depends mainly on the use of sterile bricks. How does the packaging material have oxygen barrier properties? However, in the process of using liquid milk aseptic bricks, the oxygen barrier of the aseptic brick packaging material often fails or fails to meet the expected requirements, and the quality of the liquid milk deteriorates during the shelf life. Therefore, the oxygen transmission rate should be the key monitoring performance index of the aseptic brick liquid milk production enterprise. The lower the oxygen permeability rate, the better the oxygen barrier property of the material. The liquid milk is not easy to oxidize or deteriorate during the shelf life or can satisfy more. Long shelf life requirements. In this paper, the oxygen transmission rate of aseptic brick packaging materials is tested by a professional oxygen permeability test equipment capable of testing high barrier packaging materials, providing technical and data reference for related industries.
Detection method:
The oxygen barrier test method for soft plastic packaging is divided into equal pressure method and differential pressure method. The equal pressure method absorbs oxygen passing through the sample through an internal Coulomb electricity sensor, and each oxygen molecule can release four electrons, using oxygen molecules. The linear proportional relationship between the quantity and the number of electrons calculates the oxygen transmission rate, which is not affected by the osmotic concentration and sensor environmental changes. Due to the high output efficiency and low detection limit of the Coulomb charge sensor, the oxygen permeability of the high barrier material can be accurately tested. The isobaric method can overcome the inevitable effect of the differential pressure method on the plastic container due to the pressure difference between the two sides, and is extended to the container test.
At present, the domestic oxygen pressure test for the isobaric test is in accordance with GB/T 19789-2005 "Packaging material plastic film and sheet oxidation permeability test coulomb test method" this national standard. We will use the OX2/230 oxygen transmission rate test system independently developed by Labthink to test the oxygen transmission rate of aseptic brick packaging samples.
1 , test equipment
OX2/230 oxygen transmission rate test system ( Labthink ), with ultra-high precision, independent three-chamber structure can test three identical or different samples at the same time, the temperature control range is 15 °C ~ 55 °C , the humidity control range is 0%RH , 35%RH ~ 90%RH , the film oxygen transmission rate test range is (0.01 ~ 6 ,500) cm 3 /m 2 ·24h , and can be extended to (0.07 ~ 6,5000) cm 3 /m 2 · 24h . The system also expands to test containers with oxygen transmission rates ranging from 0.0001 to 60 cm 3 /(pkg·d) . 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 materials, and oxygen barrier test of various materials, and can expand the test of bottles, bags and cans made of various materials. , oxygen permeability test of boxes and barrels.
2. Preparation of samples
The sterile brick samples were placed in an environment of 23 ° C 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
Location: Jinan Languang Packaging Safety Testing Center Test Temperature and Humidity: 23 ° C, 0% RH
Test method: Isobaric method (ie Coulomb electricity sensor method)
4. Test procedure
4.1 Test principle
The OX2/230 uses the isostatic test principle to clamp a pre-treated sample between the test chambers. Oxygen flows on one side of the membrane and high-purity nitrogen flows on the other side of the membrane. Oxygen molecules diffuse through the membrane to the high purity nitrogen in the other side and are carried to the sensor by the flowing nitrogen. By analyzing the oxygen concentration received by the sensor, parameters such as oxygen transmission rate are calculated. For packaging containers, high purity nitrogen flows within the container, and air or high purity oxygen surrounds the outside of the container.
4.2 sample clamping
Apply a layer of vacuum grease to the edge of the rim of the ventilated outdoor surface to prevent grease from being applied to the cavity intermediate disk. 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 Lightly press to bring the sample into good contact with the vacuum grease. Cover the venting cover and tighten the seal.
4.3 Detection process
OX2/230 is a highly intelligent testing device, and the testing process is convenient and easy to operate:
- Add distilled water, turn on the system air supply, and adjust the air supply pressure as required. According to the test requirements, an appropriate amount of distilled water is added to achieve the required O 2 , N 2 humidity.
- Turn on the power and run the software.
- Set test temperature, test parameters, and start test. Test parameters include equipment control parameters (test mode, number of test cycles, test time, number of REZERO cycles, etc.) and sample parameters (type, area, thickness, etc.).
- End of test, data processing.
- Turn off the air supply and power supply.
The oxygen transmission rates of the three aseptic brick packaging samples were 0.2004 cm 3 /m 2 ·24h , 0.1908 cm 3 /m 2 ·24h , 0.2127 , and the relative average of the test results between the three samples per sample. The deviation is less than 10% . Therefore, the measured oxygen permeability of the liquid milk aseptic brick packaging material can meet the barrier requirements of the liquid milk during the 6 -month shelf life.
to sum up:
The OX2/230 oxygen transmission rate test system can obtain the oxygen transmission rate with high repeatability and reproducibility when monitoring the oxygen barrier performance of the liquid milk aseptic brick, which can accurately reflect the barrier performance of the aseptic brick packaging material. The testing equipment and testing standards used in this test are also applicable to the oxygen transmission rate test of soft plastic composite film materials for other purposes, such as milk powder aluminum-plastic composite film, meat product packaging and so on. 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 barrier testing services to customers around the world, providing customers with reliable data support. Learn more testing instruments concerning the information, you can visit Labthink company to view 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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