The retort pouch has several advantages. It weighs less than a metal can. It is flexible, meaning that it can handle a lot of abuse when taken away from home or on military maneuvers. Because it is flat, it takes up little space, making it easier to carry in a backpack or pocket. The flat shape also gives the pouch an advantage during processing. In the plant, the pouch is filled with food, sealed, and then retorted at temperatures of 240 to 250 °F to commercially sterilize the contents. Because a pouch is flat, it takes much less time than a metal can does to heat the contents to the point of commercial sterilization. That can result in a better tasting product.
A retort pouch is commonly defined as a flexible pouch for low-acid foods that are thermally processed in a pressure vessel, often called a "retort." The pouch is made of layered polyester, aluminum foil, and polypropylene. Commercial sterilization occurs at temperatures greater than 212 °F (100 °C), typically 240 to 250 °F (115. to 121 °C). The retort packaging is shelf stable at room temperature.
In retort packaging, food is filled into a pouch or metal can, sealed, and then heated to extremely high temperatures, rendering the product commercially sterile. In aseptic packaging, the food or beverage is sterilized by quick exposure to ultra-high heat, rapidly cooled to an ambient temperature, and filled into sterilized containers that are then sealed in a commercially sterile environment. However, the assembled aseptic package is not further processed like retort products.