A world without refrigeration seems so distant and unimportant today, even though the refrigerator has been around for hardly more than a century. For thousands of years, our ancestors have battled the elements to ensure they could preserve food for more than a couple of days. What I want to investigate today is the ancient Romans’ approach to food preservation, especially pertaining to grain; the respective preservation methods for other foods will be addressed in further posts.

In the Roman empire, which is basically the ancient Mediterranean, there was a trinity of foods that constituted the majority of diets: grains, olive oil, and grape wine. Grain was the core of the Mediterranean diet, with bread, seeds, and all sorts of things. Olive oil was not only an important component of the diet, it was also used in lamps and was a crucial step in ancient bathing rituals. Wine was an important part of rituals and banquets, but was also one of the few safer sources of hydration in many parts of the empire which did not boast freshwater aqueducts. What further complicated situations was that wine was only produced once a year and olive oil once every two years. Each production cycle was required to produce enough to last those timeframes. Now, imagine organizing the production, transport, and preservation of all these items to Rome, a city of over a million at its peak. The challenge seems simply insurmountable without modern planes, trucks, cargo ships, and temperature-controlled shipping containers.

In terms of grain storage, the Romans approached grain storage very differently from other civilizations. Normally, grain would be stored on the ear and left unprocessed to allow the natural components of the grain to protect it from pests and weather. However, the Romans chose to complete grain processing before putting it in storage, which did make it more convenient for the average urbanite to acquire ready-to-use grain, but significantly shortened the grain’s shelf life. Therefore, Romans were particular in their optimization of storage facilities; they paid particular attention to humidity, ventilation, and temperature, the three conditions that could destroy grain in days, when constructing granaries.

How did they do this? They constructed granaries called horrea, which were often built with a central courtyard and sets of long, narrow rooms, where grain would be stored. This format would allow quick and easy access to the grain for transport workers, greatly increasing efficiency. Each room featured a raised floor, under which air could flow, improving ventilation and keeping temperatures cool. In addition, many rooms had a small window near the top of the wall to aid airflow. Horrea also had relatively thick walls made of wood or brick, providing an additional barrier against temperature and humidity. To further protect rooms, Roman builders used cocciopesto, a plaster material with both waterproofing and humidity reduction capabilities, on the walls, ceilings, and floors of granaries. Now, you might think that this is paradoxical. Still, cocciopesto is permeable enough that tiny particles of water vapor can escape, while being just impermeable enough that solid water droplets can’t penetrate.

Most interesting about horrea, in my view, is the presence of high security. Not only were there meticulous records, but many horrea boasted specialized security personnel along with the security features of the structure itself (small, high windows, thick walls, locks everywhere, and limited access points). This level of security clearly indicates the presence of another very great threat, theft and crime, so Romans had to combat the elements as well as each other in making sure food could get to every hungry mouth in a capital that was not surpassed (in terms of population) till the Industrial Revolution. Next time, we’ll be looking at smaller-scale grain storage as well as wine and olive oil storage, where we’ll explore the universality of jar storage around the world.