How Material Choice Impacts Shelf Life in Mylar Bags

Shelf life isn’t merely related to the closure of a bag; it’s also from how well the package keeps oxygen, moisture, and light from reaching the contents of the bag. The material that makes up the contents of a Mylar bag directly affects how well this realization occurs. An explanation of that will follow.

The outer layer of a Mylar bag is made of polyester. It provides structure to the bag, thereby preventing punctures and limiting stretching, which will allow the bag to maintain its shape through the handling and storage process. If the bag did not have a polyester layer, it would not have the durability it possesses.

The metallic barrier layer in the bag serves to minimize the transmission of oxygen through the bag. Oxidation caused by the exposure of food to oxygen lowers the flavor of food, and is a significant contributor to the spoilage of food. By reducing the amount of air that is exchanged between the air inside and outside the bag, a metallic core layer can greatly increase the amount of time that food remains fresh than if it were packed in a regular plastic bag.

Controlling moisture in the bag is equally important as controlling oxygen inside the bag. This is accomplished by using a laminated construction of the inner layer of a Mylar bag to separate the outside of the bag from the inside. Once the bag has been sealed, the laminated layers of the bag will work to create a controlled environment within the bag; thereby slowing the degradation of the contents after they have been sealed.

For a description of how each layer contributes to protection and shelf life, and for a complete description of what Mylar bags consist of, as well as an understanding of the construction of a Mylar bag, you may review the document outlining the composition of the Mylar bag and the function of the laminated structure in the bag.