Brewing a Gruit Ale without Hops — Medieval Herbal Beer

Heat 7 litres of water to approximately 72-74 degrees Celsius (slightly higher than modern mash temperature to compensate for heat loss when adding grain). Add the crushed pale malt to the hot water in the mash tun and stir thoroughly to eliminate dry clumps. The temperature should stabilise at approximately 65-68 degrees Celsius — the range where amylase enzymes in the malt convert starch into fermentable sugars (maltose and glucose). Medieval brewers did not have thermometers; they judged temperature by dipping an elbow or observing steam patterns. Hold the mash at this temperature for 60 to 90 minutes, stirring occasionally. During this time, the enzymes saccharify the starch, producing a sweet liquid called wort. Medieval alewives (the women who traditionally brewed ale in England) performed this step in large wooden troughs.

Drain the sweet wort from the mash tun through a strainer or false bottom, collecting it in the brew pot. Rinse the grain bed (sparge) by slowly pouring an additional 5 litres of water heated to approximately 75 degrees Celsius over the grain to extract remaining sugars. Collect all the runnings until you have approximately 10 to 11 litres of wort. The wort should taste noticeably sweet — a specific gravity of approximately 1.040 to 1.050 (measured with a hydrometer) is typical for a medieval-strength ale of about 4 to 5 percent alcohol. Medieval ales were generally lower in alcohol than modern beers, as they were consumed as a daily staple by all ages, including children (small beer at approximately 2 percent was the standard table drink).

Bring the wort to a rolling boil in the brew pot. Add the gruit herbs: sweet gale, yarrow, and rosemary. Boil for 45 to 60 minutes — this sterilises the wort, extracts flavour and preservative compounds from the herbs, and coagulates proteins that would otherwise cause haze. Sweet gale contributes a resinous, slightly bitter flavour and mild preservative action from its essential oils (particularly myrcene). Yarrow adds a spicy, slightly astringent character and has been used in brewing since at least the Neolithic period (residue analysis of pottery from 3000 BC confirms yarrow in fermented beverages). The boiling also drives off unpleasant volatile compounds. Skim any foam that forms on the surface.

Strain out the spent herbs and cool the wort as quickly as possible to approximately 20-22 degrees Celsius to prevent contamination by wild bacteria. Medieval brewers cooled wort in shallow open vessels (coolships) exposed to the air, which also inoculated the wort with wild yeasts — though most brewers also maintained a house yeast culture (barm) skimmed from previous batches. Transfer the cooled wort to a clean fermentation vessel and add (pitch) the ale yeast. Stir vigorously to aerate the wort, as yeast requires dissolved oxygen for the initial growth phase before switching to anaerobic fermentation. Seal the vessel with an airlock or loose-fitting lid that allows carbon dioxide to escape without admitting air.

Allow the ale to ferment at approximately 18-22 degrees Celsius for 5 to 10 days. Active fermentation will be visible within 12 to 24 hours as a thick, foamy head (kraeusen) forms on the surface — medieval brewers called this barm, and it was saved to pitch subsequent batches. When bubbling in the airlock slows to less than one bubble per minute, primary fermentation is complete. The ale can be served immediately (as medieval ales were — they were consumed fresh, within days of brewing) or transferred to a secondary vessel for 3 to 7 days of conditioning to clarify. Gruit ales have a complex, herbal character quite different from hopped beer — the absence of hops means there is no bitterness in the modern sense, but the gruit herbs provide their own balancing flavours, a slightly sweet maltiness, and a mild sedative-euphoric quality attributed to the myrcene in sweet gale.