Microscopic signatures of malting could help reveal which prehistoric people had a taste for beer.
Ancient beer is difficult to trace, because many of beer’s chemical ingredients, like alcohol, don’t preserve well (SN: 9/28/04). But a new analysis of modern and ancient malted grain indicates that malting’s effects on grain cell structure can last millennia. This microscopic evidence could help fill in the archaeological record of beer consumption, providing insight into the social, ritual and dietary roles this drink played in prehistoric cultures, researchers report online May 7 in PLOS ONE.
Malting, the first step in brewing beer, erodes cell walls in an outer layer of a grain seed, called its aleurone layer. To find out whether that cell wall thinning would still be visible in grains malted thousands of years ago, Andreas Heiss, an archaeobotanist at the Austrian Academy of Sciences in Vienna, and colleagues simulated archaeological preservation by baking malted barley in a furnace. Using a scanning electron microscope, the researchers observed thinned aleurone cell walls in the resulting malt residue. Heiss’s team found a similar pattern of thinning in residues from 5,000- to 6,000-year-old containers at two Egyptian breweries.
The researchers then inspected grain-based remains from similarly aged settlements in Germany and in Switzerland. These sites didn’t contain any tools specifically associated with beer-making. But grain-based residues from inside containers at the settlements did show thin aleurone cell walls, like those in the Egyptian remains — offering the oldest evidence of malting in central Europe, the researchers say.
Heiss and colleagues suspect the malted residue from one of the settlements in Germany was beer, because the sample has characteristics of dried-up liquid, such as cracks along its surface. But remains found at other sites may be other types of malted foodstuffs, like bread or porridge.
This bowl-shaped hunk of cereal residue (left) from a settlement near Lake Constance in Germany dates back to about 3910 B.C. A scanning electron microscopy image (right) of the residue reveals thinning of the cell walls around aleurone cells (marked A), which is characteristic of malted grains. The researchers interpret this as some of the oldest evidence of malting in central Europe, and possibly the oldest evidence of beer in the region.