By Travis Elliott
I am currently taking a course of Food and Drink in the Ancient Mediterranean with Professor Rabinowitz, and this semester we breifly talked about some of the refrigeration techniques from antiquity. I went on a little mission to find out more, and dug up some pretty interesting stuff! I believe the question asked was something about keeping things cool and the answer was simply that you had to live somewhere near ice or snow. However, this may be a bit too simplistic of a view. There were actually structures built for the purpose of ice storage. They were generally built by the wealthy as they required both space and money to build an underground insulated chamber to keep the ice in and keep it from the heat of the outside world. In the Greek/Roman world, Alexander the Great was credited with building the first of these refrigeration structures. These buildings didn’t generate ice, like a modern freezer can, but simply preserved it. But where did he get this technology? As with many other technologies and new ideas, we need only look to the East, in this case to Persia.
In Persia, the technology to store ice had become common by 400-500BC but was likely available to the wealthy earlier. The Persians called their ancient ice-houses Yakhchal, meaning ice pit. Roman and Greek ice pits had to be seeded with ice from mountains or snow fall and could only retard the melting process; but in the extremely hot arid climates of some areas of Persia, yakhchal were capable of producing ice during cool times, like during certain seasons or especially cold nights. The yahkchals were subterranean, like western ice houses, because it offered good insulation. But to further insulate the ice, they came up with a special mortar which may have consisted of sand, clay, egg, goat hair, ash, and other materials that when mixed together, helped keep the summer heat out and the icy cool in. The final technological element to many yakhchal, and one that helped them turn liquid water into ice, was a complex evaporative cooling and windcatching system that pulled the hot air on the top of the chamber out and left the cold air above the ice so that it wouldn’t melt. Any ice that did melt would evaporate off the top of the block, helping keep the remainder cool.
In any Persian village with access to water, an ice house would be built adjacent to agricultural walls and had small canals that ran to the ice house from a point of water. The canals would be built in the shade of the agricultural walls to keep the water cool on the way to the ice house. During the winter, they would channel water from the village well (Qanat) down the cold canals, further cooled by the shade of the walls, and into the subterranean storage tank of the yakhchal. Night after night, thanks to the extreme low temperatures of the Persian deserts, the water inside would freeze. Due to the insulated superstructure, the ice would stay solid throughout the day and any that melted would be evaporated, pulling any heat away from the block underneath.
Theyakhchals weresuch an important part of ancient Persian life that modern refrigerators share the name with these structures. In their heyday, they could be used to store any perishable food stuffs or make a regional dessert known asfaloodeh. The remnants of these still stand in some villages (where they are possibly still used) and in modern cities in Iran.
If you’re interested in learning more about these fascinating refridgeration systems, below is a link to a real study with all the science behind the study: