1-19. RETORT POUCHES
a. Characteristics. The retort pouch is a flexible, heat sealable container that is
thermally processed like a can and may be used to produce shelf stable, commercially
sterile food products. It is constructed of a 3-ply laminate composed of an outer layer of
polyester film, a middle layer of aluminum foil, and an inner layer of polypropylene. The
layers are bonded together with an epoxy adhesive. The polylaminate material provides
seal integrity, toughness, puncture resistance, and superior barrier properties for long
shelf-life. It also withstands the rigors of thermal processing up to 275oF (135oC). Much
of the retort pouch development was conducted by the U.S. Army Natick Research and
Development Center for use in the Meal, Ready-to-Eat (MRE), an individual operational
ration.
b. Specific Dimensions. Each layer of this polylaminate has a specific
function. The outer polyester film is approximately 0.0005 inch thick and resists
scuffing, flexing, and other mechanical damage. The flex resistance prevents flex
cracking in the aluminum foil layer. The middle aluminum foil layer is 0.00035 inch thick
and acts as a gas, light, and moisture barrier. The inner polypropylene layer is 0.0003
inch thick and is the inert food contact layer, which also provides the fusion bonded seal
when heat and pressure are applied.
c. Advantages and Disadvantages. The retort pouch offers several
advantages over the steel tin-plated can. Shorter retort times may be used due to its
flat configuration and shorter distance to the geometric center. Due to the inert
properties of the pouch materials, chemical corrosion of the interior and exterior
surfaces is almost nonexistent. The retort pouch also weighs less than the steel tin-
plated can. Some of the disadvantages include a lack of physical durability and slow
production rates.
d. Parts of a Retort Pouch. The parts of a retort pouch may be noted in Figure
1-12. The parts are: the lip, the tear notches, the final seal (at the top), the side seal,
and the bottom seal.
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