An archeobotanist has discovered a 2550 year-old recipe for ancient Celtic malt beverage.
Hans-Peter Stika of the University of Hohenheim in Stuttgart has been spending time at ancient Celtic sites, figuring out how the local groups made their beer, reports Science News.
He said that six specially constructed early Celtic ditches, previously excavated at Eberdingen-Hochdorf, a 2,550-year-old settlement in Germany, were used to make high-quality barley malt, a key beer ingredient.
Thousands of charred barley grains unearthed in the ditches about a decade ago came from a large malt-making enterprise.
The researcher bases that conclusion on a close resemblance of the ancient grains to barley malt that he made by reproducing several methods that Iron Age folk might have used.
He also compared the ancient grains to malt produced in modern facilities. Upon confirming the presence of malt at the Celtic site, Stika reconstructed malt-making techniques there to determine how they must have affected beer taste.
At the Celtic site, barley was soaked in the specially constructed ditches until it sprouted, said Stika.
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 added sourness to the brew.
According to Stika, unlike modern beers, the Eberdingen-Hochdorf brew probably contained spices such as mugwort, carrot seeds or henbane.
Excavations at the Celtic site have yielded a few seeds of henbane, a plant that also makes beer more intoxicating.
"These additives gave Celtic beer a completely different taste than what we're used to today," said Stika.
Heated stones placed in liquefied malt during the brewing process - a common practice later in Europe - would have added a caramelised flavour to this fermented Celtic drink, he added.
Stika suspected that fermentation was triggered by using yeast-coated brewing equipment or by adding honey or fruit, which both contain wild yeasts.
Celts consisted of Iron Age tribes, loosely tied by language and culture, that inhabited much of Western Europe from about the 11th to the first century B.C.
Classics professor Max Nelson of the University of Windsor in Canada, an authority on ancient beer, largely agrees with Stika's conclusions.
According to him, other stages of brewing occurred either at the site, as suggested by Stika, or nearby.
"Stika's experiments go a long way toward showing how precisely barley was malted in ancient times," he said.
Beer buffs today would regard Celtic beer as a strange brew not only for its flavour but because it would have been cloudy, contained yeasty sediment and been imbibed at room temperature, he added.
The study is published online in Archaeological and Anthropological Sciences.