Which packaging innovation, first widely deployed for military rations during WWII, revolutionized food preservation for troops and later became standard in civilian markets?

Throughout military history, packaging innovations have played a crucial role in soldier nutrition and combat effectiveness. One particular packaging breakthrough revolutionized how military rations were preserved and distributed to troops in the field. This innovation changed military logistics and later found its way into civilian food preservation. Test your knowledge about this significant packaging development that transformed military food supply chains and eventually civilian food preservation methods.

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Retort pouches (flexible packaging that could be heat-sterilized)
SPAM cans (key-opened tin containers with pressed meat)
MRE (Meals, Ready-to-Eat) polymer bags with oxygen absorbers
Dehydrated food packets in waterproof packaging