When was freeze dry food invented?

It's tricky to pinpoint an exact date for the invention of freeze-drying food, as the process evolved over time with different contributors.

Here's a breakdown of key milestones:

* Early Attempts: The principle of removing water from food by freezing and then sublimating the ice under vacuum existed long before the term "freeze-drying" was coined. Ancient civilizations like the Incas likely used natural freeze-drying methods to preserve food.

* 18th Century: The development of vacuum pumps in the 18th century allowed for more controlled freeze-drying techniques.

* 1900s: A critical step in freeze-drying technology came in the early 1900s with the development of the lyophilizer (also known as a freeze-dryer). This machine allowed for faster and more efficient freeze-drying.

* World War II: Freeze-drying technology saw significant advancements during World War II due to its use for preserving blood plasma and other medical supplies for the military.

* Post-War Development: Following the war, the process was adapted for preserving food for the civilian market and for space travel. The first commercial freeze-dried foods became available in the 1960s.

Therefore, rather than a single invention date, we can say that freeze-drying technology evolved over centuries with key contributions from various individuals and events. The 1900s and the period around World War II mark significant breakthroughs in the development of this food preservation method.