Food bags used for freezing are different from general food packaging bags. Due to the particularity of freezing, the choice of food packaging bags is unique. So, what should you pay attention to when choosing frozen packaging bags for food?
When choosing frozen food packaging bags, you should first study the main ingredients of frozen food, especially the sensitive factors that affect nutrients such as fat, protein and vitamins, including light, oxygen, temperature, microorganisms, physical and mechanical factors. Then, according to the protection requirements of the contents and transportation environment, the type of packaging materials and the operation mode of packaging technology are determined to achieve the protection function and appropriately extend the shelf life.
Health & safety
From a safety perspective, packaging materials (such as plastic bags) that come into direct contact with food must be food grade. The packaging and transportation process of frozen food is usually difficult to ensure that the entire process is carried out in a continuous low-temperature environment, especially during transportation and handling, which may cause the temperature of the frozen food to rise significantly within a certain period of time. If the raw materials are unqualified, it is easy to produce bacteria. Compared with packaging made of recycled materials or industrial-grade materials, there is not much difference in their appearances. However, the plasticizers and other substances they contain exceed the standards. Once used, they will be harmful to human health.
Cold resistance
Frozen food is usually stored and circulated at temperatures of -18°C or even lower, especially some frozen food with trays. During the production process, food and trays are usually rapidly cooled at -30°C until the core temperature of the product is lower than -18°C before being packaged. When the temperature drops sharply, the mechanical strength of the packaging material also decreases, the packaging materials to be brittle.
In addition, frozen food is inevitably subject to shock, pressure and other environmental hazards during transfer and transportation. Moreover, frozen food such as glutinous rice balls and dumplings are difficult to eat at low temperatures. It is easy to cause cracking of packaging bags, which requires packaging materials to have good low-temperature properties.
Impact resistance
Frozen food is easily damaged by external forces during transportation, loading, unloading and shelf placement. When the impact resistance of the packaging bag is poor, it is easy to break the bag and open the bag, which not only affects the appearance of the packaged product, but the impact resistance of the packaging bag can be measured by the pendulum impact resistance test.
Heat sealing strength
If the heat-sealing strength of the packaging bag is insufficient or the seal is not good, a slight impact will cause the seal to rupture; if the heat-sealing temperature is too high, it will easily cause damage to the heat-sealing layer and reduce the material strength of the sealing line. Once it is subjected to strong vibration or impact, it is easy to cause bag rupture and large-scale bag damage, which makes it impossible to effectively protect the internal packaged food.
Tension and strength of interlayer peeling
If the peeling strength between packaging bags is small and the tensile force is not enough, the mechanical properties of the packaging bags will be poor, which will easily cause the packaging bags to be delaminated and unable to achieve the proper load-bearing function. The protective properties of packaging bags greatly shorten the shelf life of the food inside.
Puncture resistance
Frozen food usually hardens after freezing, especially fish and meat products, which contain bones and hard objects. It is easy to puncture the packaging bag during transportation and stacking after the product is extruded. The sealing of the packaging bag is damaged, so the puncture resistance of frozen food packaging bags is very high.
Pressure resistance
During transportation and loading and unloading, vibration, dropping or impact will damage the transportation packaging and even internal sales packaging. Therefore, relevant vibration or drop tests should be carried out on frozen food packaging. Choose packaging materials that can protect the quality of frozen food, reflect its commodity value, and make the overall packaging cost reasonable.