Although, It is not known exactly how people in ancient times may have freeze-dried food, as there are no written records describing the process. It is believed that some ancient cultures may have utilized a primitive form of freeze-drying by exposing food to cold temperatures and wind, which would have caused the moisture in the food to evaporate.
One example of a culture that may have used this technique is the Incas of South America. The Incas lived in the Andes Mountains, where the temperature could drop to below freezing at night. They would lay out food, such as potatoes, on large rocks or in fields and allow them to freeze overnight. The following day, they would expose the frozen food to the strong winds of the Andes, which would cause the ice in the food to evaporate, leaving behind a freeze-dried product.
Another example of a culture that may have utilized a form of freeze-drying is the Indigenous people of North America. They would hang fish and meat in the cold, dry air of winter and allow them to freeze and dry out. This would preserve the food and make it easier to transport and store for long periods.
While these methods of food preservation were not as sophisticated as modern freeze-drying techniques, they were effective in preserving food and allowed ancient cultures to store and transport perishable items over long distances.