St. Gallen was a monastery in Switzerland founded as a small hermitage and cloister by an Irish missionary named Gallus around 590 ad. Over centuries, this monastery became an important fount of European brewing culture and knowledge. By the 720s, the cloister had achieved monastery status and around 800, during the reign of Charlemagne, it became an imperial abbey. Little more than 20 years later, its installations included a church, a cloister, a library, a school, a hospital, a pilgrims’ hostel, dining halls, the monks’ sleeping quarters, dormitories for workers and tradesmen, guest houses for visitors of lofty rank, elaborate gardens and lawns, workshops, bath houses, latrines, a water-powered mill, and three breweries. Eventually, St. Gallen would evolve into the world’s largest and most sophisticated brewery operation of its time, and its light of spiritual and material culture would shine into all of Central Europe. We have excellent contemporary accounts of this, preserved in the architectural plan of the monastery of St. Gallen, drawn up in 829 ad, and a 1060 ad chronicle penned by St. Gallen’s Abbot Ekkehard IV, entitled Casus St. Galli (The Case of St. Gallen). Both documents are now in the St. Gallen Library, the Stiftsbibliothek, a UNESCO World Heritage Site.
Each of the monastery’s three breweries was dedicated to making a different type of beer. One brew was a strong beer called celia, made from barley, sometimes from wheat, or frequently from both. It was reserved only for the abbot and his inner circle and his high-ranking visitors. The second brew, called cervisa, was a beer of milky-sour taste, usually made from oats, and flavored with herbs and sometimes with honey; the latter version was called cervisa mellita. This was the monks’ and pilgrims’ everyday beer and was consumed like water throughout the day. The third brew, called conventus, was a thin “small beer” made from the final runnings of the stronger beers and mixed with fresh extract from malted oats.
St. Gallen’s three breweries represented the first truly large-scale brewing operation in Europe. They were spread out over 40 buildings and yielded perhaps 10 to 12 hectoliters of beer a day. It took more than a hundred monks, twice as many serfs, and an even larger number of pupils from the monastery school to tend the oat, wheat, and barley fields and to run the breweries. In the granary, the monks threshed the reaped grain and moistened it until it sprouted. They dried it in a separate room, in a kiln that shared its heat source with a brew kettle. Once fully malted, they coarsely crushed the grain in two huge, water-powered mortars. Each brew kettle served as both mash tun and cooker. While most brew kettles at the time were heated by hot stones dropped into the mash or just by an infusion of hot water, the kettles at St. Gallen were direct-fired. They were mounted over round furnaces, whose walls were made from a mesh of willow reed filled with clay. Each furnace was large enough for a monk to stand up in and patch the clay walls. A flue at the top of the furnace led away the smoke, either into the open air or into the kiln. The monks ladled the wort with wooden buckets from the kettles through filters of pressed straw into flat, wooden tubs, made of hollowed tree trunks. These stood in cooling rooms adjacent to the brewhouses. Fermentation occurred in separate wooden tanks placed between the cooling vats. Although yeast and its role in fermentation was unknown at the time, the St. Gallen monks had already learned that adding a bit of already-fermenting beer from a neighboring tank (rich with active yeast) to a fresh batch or pouring fresh wort over the sediments left behind by a previous batch would jump-start fermentation. The monks also learned that mixing the residue from the fermented beer with bread dough would make the bread rise faster. The St. Gallen beer was, by all accounts, of good and consistent quality, a great achievement in the Middle Ages, when mankind’s knowledge of microbes was still centuries into the future.