Excavation of the area near the burial site of a Celtic prince has revealed some charred barley in six ditches.
More from ScienceNews.org:
At the Celtic site, barley was soaked in the specially constructed ditches until it sprouted, Stika [an archeobotanist with the University of Hohnheim at Stuttgart] proposes. Grains were then dried by lighting fires at the ends of the ditches, giving the malt a smoky taste and a darkened color. Lactic acid bacteria stimulated by slow drying of soaked grains, a well-known phenomenon, added sourness to the brew.mmm ... smoked malt, carrot seed, and honey with a wild, sour, lactic fermentation. Henbane, not used in modern brewing, is a psychoactive drug that would have caused visual hallucinations, not to mention tachycardia, convulsions, and vomiting.
... The Eberdingen-Hochdorf brew probably contained spices such as mugwort, carrot seeds or henbane, in Stika’s opinion. Beer makers are known to have used these additives by medieval times. Excavations at the Celtic site have yielded a few seeds of henbane, a plant that also makes beer more intoxicating.
Heated stones placed in liquefied malt during the brewing process — a common practice later in Europe — would have added a caramelized flavor to this fermented Celtic drink. ... He suspects that fermentation was triggered by using yeast-coated brewing equipment or by adding honey or fruit, which both contain wild yeasts.
I'm most intrigued by the malting process, though. While all of the malt would have had some smokiness, the malt closest to the fires would have been almost black, while that in the middle of the ditch, less so. Given the finding of charred malt, perhaps the malt in the middle, uncharred and, depending on how long the ditch is, probably not even deeply roasted, would have made for something more closely resembling a deep gold or light amber color, rather than the dark, black color implied by the article.
It is also somewhat difficult to gauge how strong, alcoholic, the beer would have been. While far from the most efficient way to make beer, if left to age long enough, which it likely was not, it could have become quite strong - maybe 4-5% ABV or so. Moreover, the fermentables in the honey or other added fruits could have boosted the alcohol content significantly.
The addition of henbane seems kind of interesting, as well. If this would have been the sole, or even primary, drink they would have spent much of their waking hours completely stoned. While not out of the realm of possibility, this seems unlikely; if only because some people do not process henbane well and would have had severe negative reactions to it. For that reason, it would be my own conjecture (completely scientifically based of course) that they would have either reserved this for special occassions, and chose to drink something not quite so toxic for their basic sustenance. For instance, there are Norse myths about using psychoactives in battle to reduce desertion and fear. Not to mention the use of henbane in Ancient Greece by oracles.