Which consumer food preservation technique was first widely developed for military use during World War II before becoming a common retail product category?

Military innovations have often found their way into everyday consumer products. MREs (Meals, Ready-to-Eat) and combat rations developed for soldiers have influenced civilian food technology and marketing. This trivia explores how military food technology crossed over into consumer retail products and changed shopping behaviors. Test your knowledge about how battlefield nutrition became supermarket staples!

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Freeze-drying (used first for blood plasma preservation, then commercialized for coffee and camping foods)
Vacuum sealing (developed for artillery shell preservation before being adapted for food)
Spray drying (invented for weapon coating before being applied to powdered milk and eggs)
Nitrogen flushing (created for ammunition storage before becoming standard for packaged snacks)