Do Mylar Bags Block UV Light for Food Preservation?

Mylar Bag Composition and UV Blocking

Mylar bags are made from a type of polyester film called BoPET (Biaxially-oriented polyethylene terephthalate). The thickness of the film varies, but a standard Mylar bag is typically around 0.0003 inches (7.6 microns) thick. This thin film allows some UV light to pass through, making it a relatively weak barrier against UV radiation.

UV Blocking Efficiency and Storage Recommendations

Studies have shown that Mylar bags can block up to 90% of UV-A light and 80% of UV-B light. However, this level of UV blocking may not be sufficient to prevent the degradation of all food types. For example, fatty foods like nuts and seeds may still undergo rancidity or oxidation even with minimal UV exposure. To ensure food preservation, it’s recommended to store food in a Mylar bag with an oxygen-absorbing packet, such as silica gel or activated carbon, and to keep the bag in a dark or shaded area. If you’re storing food for an extended period, consider using a thicker Mylar bag or an alternative storage material like glass jars or steel containers.

Comparing Mylar Bags to Other Storage Options

When comparing Mylar bags to other storage materials, it’s essential to consider their UV blocking efficiency and overall performance. Aluminum foil, for instance, is a more effective UV blocker than Mylar bags, but it’s not as durable or flexible. Glass jars, on the other hand, offer excellent UV blocking and are a popular choice for long-term food storage. However, they may require additional protection from impact and breakage. Steel containers, like buckets or cans, provide excellent UV blocking and are durable, but they can be heavy and more expensive than Mylar bags. The choice of storage material ultimately depends on your specific needs and preferences.