Vacuum packaging bags surround us every day, from keeping food in the fridge to packing small things when on vacation. But how much can they stand in terms of heat? Understanding their temperature limits is crucial for safe use; too much and they will melt, explode, or even produce poisonous chemicals. So let's take a closer look.

Temperature Limits by Material

Most vacuum bags are made primarily of two types of plastic: PE and PP. Each material has varying heat resistance.

The most commonly used are PE bags. They may be used for general usage but not as durable for high temperatures. Under normal circumstances, they can sustain temperatures of 60-80°C. Problems occur when the temperature is greater than 80°C; the bag can become soft, warp, or stick together, and no longer seals properly.

PP bags are heat-resistant. They are able to withstand heat at the range of 100-120°C. This is the main reason why they are most commonly used to package food that barely requires heat, such as pre-prepared foods that require minimal heat, such as pre-prepared meals that might need to be heated quickly. But even they have their limits, above 120°C they start to break down.

What factors influence the heat resistance of vacuum packaging bags?

Thickness is important.

Thick bags hold better at hot temperatures than thin bags. Thick materials slow down the transmission of heat, i.e., they can hold higher temperatures for shorter periods. Thin bags, on the other hand, easily penetrate heat and break down much quicker.

Time in high temperatures

It is not just the temperature, but also the duration. A PE vacuum packaging bag may be fine at 70°C for 10 minutes, but if left there for an hour, then most likely it will deform. Even PP bags will begin to deteriorate if left at 110°C for too long.

Quality of vacuum packaging bags

Not all bags are created equal. Cheap or low-quality bags are constructed using recycled material or less pure plastic, which reduces their heat resistance. They can begin to melt or leak below the official temperature limit. Choose well-made bags for greater reliability.

How Vacuum Packaging Bags Perform in Common Scenarios

Low-Temperature Conditions: No Problem

Vacuum packages perform magnificently in low temperatures. They can handle refrigerator and freezer temperatures without problem. This is perfect for storing meat, vegetables, or leftovers in the freezer for weeks at a time without cracking or breaking.

Microwaving: Risks

It's not a good idea to microwave vacuum packaging bags, even if they are polypropylene. Microwaves heat unevenly and can create hot spots of more than 150°C, far greater than the tolerance of the bag. The material inside the bag can also overheat and melt or burst the bag. Take the food out of the bag prior to microwaving.

Boiling Water Immersion: Proceed with Caution

PE bags cannot withstand the heat of boiling water; they will soften and break within seconds. PP bags can be briefly submerged, but do not leave them submerged in boiling water for more than a few minutes. Longer soaking than one or two minutes will weaken them, potentially breaking the seal and allowing water in.

Special High-Temperature Applications

For use commercially or industrially, various vacuum bags employ multi-layer films, e.g., PE or PP with other heat-resistant films. These bags will be capable of operating within temperatures of 130-150°C and thus be used, for instance, in pasteurization processes, where food is heated within sealed pack to kill bacteria. These bags are likely to be thicker and more expensive than the standard domestic vacuum bags. Before use in such high-temperature applications, make sure to refer to the product label for the correct temperature rating.

Tips for safe use

Keep vacuum-packed bags away from hot pots, ovens, or stovetops. Even brief contact with a 200°C pot can melt them.

Let hot food cool to room temperature before sealing it in a vacuum bag. Hot food (over 60°C) can cause the bag to go soft on the inside and weaken the seal.

If you must reheat foods in vacuum packages, transfer them to a heat-proof container first. Safety first.

Vacuum packaging bags have specific temperature limits. PE bags are 60-80°C resistant, while PP bags are 100-120°C resistant. Heat resistance depends upon thickness, length of time in a heated condition, and quality. They are suitable for application in low-temperature environments like refrigerators and freezers but unsuitable for microwaves and hot water. Specialized multi-layer pouches can be more heat-resistant and find industrial applications. Know these limits and utilizing them with care will ensure food safety while ensuring proper function of your vacuum packaging bags. Wancai is a China vacuum packaging bag manufacturer. If you would like to learn more about plastic packaging bags, please contact us.