Frozen Food Bag with EVOH Multi-Layer Barrier and Low-Temperature Impact-Resistant Freezer Packaging

Freezer burn is not, as commonly believed, the result of low temperature itself. It is caused by sublimation — the direct phase transition of ice from solid to vapor without passing through the liquid phase. Inside a frozen food package, microscopic ice crystals on the food surface sublimate into water vapor, which then migrates through the headspace and re-deposits as larger ice crystals on the coldest available surface: the inner wall of the packaging film. Every cycle of this process removes moisture from the food and transfers it to the package interior, leaving behind the desiccated, leathery, discolored patches that define freezer burn. The rate is accelerated by temperature fluctuations during the defrost cycles of automatic-defrosting freezers.

The solution requires an oxygen barrier layer — counterintuitively, because freezer burn is a moisture problem, not an oxidation problem. However, oxygen catalyzes the oxidation of unsaturated fats even at freezer temperatures, and lipid oxidation products accelerate protein denaturation, compounding the dehydration damage. Our EVOH (ethylene vinyl alcohol) barrier layer delivers oxygen transmission rates below 0.5 cc/m²/day, effectively eliminating oxidative co-damage. The EVOH is co-extruded between two tie layers of maleic anhydride-grafted PE that bond the polar EVOH to the non-polar polyethylene structural layers — a buried barrier architecture that protects the moisture-sensitive EVOH from direct contact with high-humidity environments that would otherwise plasticize and degrade its barrier performance.

The outer structural layers incorporate a low-temperature impact modifier that shifts the ductile-to-brittle transition temperature well below -20°C, ensuring the film absorbs impact energy — from stacking, transport vibration, and consumer handling — without crack initiation. Key applications: frozen vegetables, frozen fruits, frozen prepared meals, frozen seafood, and frozen bakery products.