What naturally protects eggs from spoiling? What process removes #1 from eggs? Did #2 exist during the Middle Ages?
Middle Ages
When eggs are freshly laid, they are covered in a film called a 'bloom.'  Eggs with their bloom intact are able to stay at room temperature for one month. Pasteurization destroys the bloom on eggs.  Pasteurization was introduced in the 1990's.
Period of European history from the 5th to the 15th century
Did eggs need to be kept cold in the middle ages?