What is a retort pouch made of? A retort pouch is commonly defined as a flexible packaging 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. What is a retort pouch used for? A retort pouch is a thin, lightweight, flexible laminated plastic package used to hold processed foods. It's essentially a can and glass jar replacement product that combines the longevity of traditional food preservation methods with the convenience and benefits of a thin, relatively malleable container. Why is it called a retort pouch? Retort Pouch and Tray Technology. The retort pouch bag is a misnomer, since the name today denotes a flexible pouch for low-acid foods terminally sterilized in a pressure vessel often called a retort. Are retort pouches recyclable? Standard retort pouches are not recyclable, because they are made from mixed materials.