Plastics, anti-oxidation layers, and substrate. Some manufacturers may throw in a layer of other materials to enhance security and usability. In juice stand up bags, the primary material used is films of plastic. These films are laminated together to make a multiple layer structure that protects juices from oxidation. This structure of pouch bags forms an effective barrier against environmental impurities. Bags with a foil can protect juices from the sun’s ultraviolet rays. These foil pouches can be made puncture resistant to withstand even the roughest handling.
There is little information available on what materials were used when Capri Sun first used stand up pouches to package its juice products during the early 1960s. During the boom in stand up bag usage during the 1990s, manufacturers opted for plastics. In the absence of a cheaper and similarly reliable material, the choice has stayed the same to this day. Manufacturers may experiment with the materials used in spouts, but most of them are still made of plastic. Theoretically, however, metal spouts can be used. Economic feasibility keeps manufacturers from trying that. Plastic pouches with plastic spouts are an inexpensive method to package juices.