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On the packaging of potato chips, beverages, and other food products, the author often sees a notice: if you find swelling or leakage, do not open it for consumption. After paying attention to this sentence, the author often pays attention to whether these inflatable packaging have the above phenomenon, but has not encountered it yet. Entering the food machinery industry, the author only learned that packaging for this type of food undergoes sealing tests before leaving the factory; For packaging such as vacuum, nitrogen filling, and mixed gas filling, oxygen testing will also be conducted to ensure that the product packaging is intact.

Packaging sealing tester

Generally speaking, sealed food packaging materials eliminate the possibility of food communicating with the outside air, and with the prior action of sterilization equipment, food can be kept in a relatively sterile state for a long time, further extending the storage time of food. Testing the sealing of food packaging requires the use of a sealing tester.

There are various measurement methods for packaging sealing testers. One is to compare whether the packaging is tight, and the measured workpiece needs to be used as a reference for weighing and comparison; You can also record the pressure values at different times to see if there are any changes. If the difference between the two is significant, it indicates that there is a leak.

Another way is to directly observe the packaging status. Generally speaking, it is necessary to first remove the gas from the vacuum chamber, then immerse the sample in water to observe bubbles, or directly expose the sample to a vacuum environment to observe the shape of the packaging. This requires the environment to maintain a vacuum state because the vacuum state is not directly visible like color. To ensure that the test is indeed carried out in a vacuum environment, some companies have equipped negative pressure sealing testers with digital preset alarms and automatic constant pressure air replenishment equipment. The former can preset the vacuum degree and holding time, while the latter ensures that the test can be carried out under preset direct air conditions, ensuring that the direct air state can be perceived.

Oxygen testing equipment

For devices such as vacuum packaging machines and modified atmosphere packaging machines that are sealed after inflation, in addition to the sealing performance of the packaging itself, the gas content inside the food packaging determines whether microorganisms can breathe and is also a key factor in whether the food deteriorates. Testing is required before leaving the factory, usually using hydrogen testing equipment for testing.

Earlier, oxygen testing required extracting the gas from the packaging bag before conducting the test. This will encounter many limitations, such as some liquids being loaded too full, which can easily be extracted simultaneously during sampling, affecting the accuracy of the equipment; Some packaging with very small space, such as products protected by bubbles, contain less than 2ml of gas and have too few samples to analyze; However, some common combinations of packaging such as glass containers and bottle stoppers cannot be sampled without air entering

In this situation, people have developed optical oxygen measuring equipment, which can be flexibly processed according to different packaging characteristics. For liquid filled packaging, the optical oxygen measuring equipment comes with a pushpin sampler that has fluorescence sensing substances. After being left in the packaging, the sensing substances can be irradiated with an analysis rod; For packaging with insufficient gas, the front end needle is equipped with pressure compensation and fluorescent sensing substances, which can be easily tested. For packaging that is difficult to penetrate, as long as the fluorescent film with the sensing substance is placed on the inner wall of the container before packaging, and after packaging is completed, an analysis probe can be used for irradiation analysis.

Food, as a perishable food, can quickly spoil and become inedible when exposed to air. Packaging, as a device for separating food from air, water vapor, and oxygen, lacks airtightness and contains too much hydrogen gas, which can lead to premature deterioration of the food. Therefore, in the food production process, measurements such as sealing and oxygen value of food packaging cannot be ignored. Relevant testing equipment production enterprises also need to accelerate the research and development and upgrading of equipment, promote the improvement of testing convenience, and provide more comprehensive protection for food.

Source: China Food Machinery and Equipment Network Title: Sealing and Hydrogen Testing Devices Make Food Packaging Leaks Hidden Everywhere