The Great Beer Experiment
The Experiment
The experiment was carried at Billy’s home in Cordarragh, Headford, Co. Galway. Seeking authenticity in replicating our Bronze Age ale we decided that our equipment should be as basic as possible. The wooden trough, posthumously donated by Billy’s granduncle, was 60 years old, leaky, wedge-shaped and measured 1.7 m in length, 0.7 m in width with a depth of 0.65 m (roughly consistent with the average trough dimensions from excavated examples). When filled with water to a depth of 0.55 m, it held 350 litres. After digging a pit, the trough was lowered into the ground and water added. Despite some initial leakage we eventually reached an equilibrium in the water level by simply flooding the immediate area. For the purposes of our experiment we sourced granite and sandstone from Connemara.
The stones were heated in a fire for roughly two hours. Step one involved transferring the heated stones into the trough using a shovel. After 15 minutes we achieved our optimum temperature of 60-70c. At this point we half submerged a wicker basket in the trough and began to add our barley in small amounts to prevent the mash from congealing. Over a period of 45 minutes, maintaining a fairly constant temperature with the addition of occasional heated stones (some of which were recovered from the trough and reheated) our water transformed into a sweet, syrupy, workable wort.
After converting the starches to sugar, ascertained by tasting the mash, we brought the mixture to a boil to sterilise it and simply baled the final product into fermentation vessels. We used spigoted plastic containers with a total capacity of 75 litres. Including the leftover liquid we could easily have produced up to 300 litres of wort. At this point we added flavourings, the majority of which were growing around us in Billy’s garden. These additives were ground in a mortar, wrapped in muslin and suspended in the top of our wort. We added 150 ml of brewer’s yeast after cooling the vessels in a bath of cold water for 3 hours.
We produced what is more properly termed a gruit ale (gruit is a term used to describe the herbal mix used to flavour ale). Through our experiments, we discovered that the process of brewing ale in a fulacht using hot rock technology is a simple process. To produce the ale took only a few hours, followed by a three-day wait to allow for fermentation. Three hundred litres of water was transformed into a very palatable 110 litres of ale with minimal work.