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Beer was here! A new microstructural marker for malting in the archaeological record

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Beer was here! A new microstructural marker for malting in the archaeological record

image: The bowl-shaped charred cereal product ("brei mit napfförmiger oberfläche") from Hornstaad--Hörnle IA. Find no. Ho 45/43-28. Top: light micrograph (red square: location of SEM subsample), bottom: SEM images. Left: patch of regularly arranged aleurone cells (A) with a conspicuous intercellular space (*) in between. L... longitudinal cells, right: fracture through the outer caryopsis layers, the multiple aleurone layers (A1 -A3) identify the material as cultivated barley (Hordeum vulgare) as do the thin-walled transverse cells (T). SE... starchy endosperm (fused remains), N? ... probably nucellus tissue, L?... probably longitudinal cells, E... epidermis (abraded).. Images: ÖAW-ÖAI / N. Gail (light micrograph), A. G. Heiss (SEM) view more 

Credit: Heiss et al, 2020 (PLOS ONE, CC BY)

A new method for reliably identifying the presence of beer or other malted foodstuffs in archaeological finds is described in a study published May 6, 2020 in the open-access journal PLOS ONE by Andreas G. Heiss from the Austrian Academy of Sciences (OeAW), Austria and colleagues.

A beverage with prehistoric roots, beer played ritual, social, and dietary roles across ancient societies. However, it's not easy to positively identify archaeological evidence of cereal-based alcoholic beverages like beer, since most clear markers for beer's presence lack durability or reliability.

To explore potential microstructural alterations in brewed cereal grains, Heiss and colleagues simulated archaeological preservation of commercially-available malted barley via charring (malting is the first step in the beer-brewing process.). They compared these experimental grains with ancient grains from five archaeological sites dating to the 4th millennium BCE: two known beer-brewing sites in Predynastic Egypt, and three central European lakeshore settlements where cereal-based foods were found in containers, but the presence of beer was not confirmed.

Using electron microscopy, the authors found their experimental barley grains had unusually thin aleurone cell walls (specific to grains of the grass family Poaceae, the aleurone layer is a tissue forming the outermost layer of the endosperm). The archaeological grain samples across all five prehistoric sites showed the same aleurone cell wall thinning.

Although there are other potential reasons for this type of thinned cell wall (such as fungal decay, enzymatic activity, or degradation during heating--all of which can be ruled out with careful analysis), these results suggest that this cell wall breakdown in the grain's aleurone layer can serve as a general marker for the malting process.

This new diagnostic feature for confirming the presence of beer (or other malted beverages/foodstuffs) in artifacts works even if no intact grains are present. A novel tool for identifying the possible presence of beer in archaeological sites where no further evidence of beer-making or -drinking is preserved, this method promises to broaden our knowledge of prehistoric malting and brewing.

The authors note: "Structural changes in the germinating grain, described decades ago by plant physiologists and brewing scientists alike, have now successfully been turned into a diagnostic feature for archaeological malt, even if the grains concerned are only preserved as pulverized and burnt crusts on pottery. A "small side effect" is the confirmation of the production of malt-based drinks (and beer?) in central Europe as early as the 4th millennium BC." Dr Heiss adds, "For over a year, we kept checking our new feature until we (and the reviewers) were happy. However, it took us quite a while to realize that en passant we had also provided the oldest evidence for malt-based food in Neolithic central Europe."


Citation: Heiss AG, Azorín MB, Antolín F, Kubiak-Martens L, Marinova E, Arendt EK, et al. (2020) Mashes to Mashes, Crust to Crust. Presenting a novel microstructural marker for malting in the archaeological record. PLoS ONE 15(5): e0231696.

Funding: AGH, FA, HPS, MBA, SMV received funding from the European Research Council (ERC-CoG-2015, GA 682529) AGH, FA, NB received funding from the Cantonal Archaeology of Zürich EM received funding from the RBINS HK received funding from BRAXAR GmbH HS received funding from the DFG (62215951) KMC, LKM, MC received funding from the NCN (UMO-2014/13/B/HS3/04976) LKM received funding from BIAX Consult MB received funding from the Japan Society for Promotion of Science (Grant-in-Aid for Scientific Re-search (C), 16K03167). Additional remarks: Experimental approaches and their evaluation were funded by the European Re-search Council within the framework of the project 'PLANTCULT': Identifying the Food Cultures of Ancient Europe, under the European Union's Horizon 2020 Research and Innovation Program (Grant Agreement No. 682529, Consolidator Grant 2016-2021, PI Soultana Maria Valamoti). Archaeobotanical analysis of the Hierakonpolis material was financially supported by the unit "Quaternary Environ-ments and Humans" of the Royal Belgian Institute for Natural Sciences (RBINS), Brussels. Excavations at Hierakonpolis were undertaken under the auspices of the Hierakonpolis Expedition with funds provided by the Japan Society for Promotion of Science within the Grant-in-Aid for Scientific Research (C) programme (proj. no. 16K03167). The analysed materials from Tell el-Farkha were excavated in the 2017 campaign which was funded by the National Science Centre Poland (NCN) as part of the project "Sociopolitical transformations in the Eastern Nile Delta at the transition between the 4th/3rd millenni-um BC" (grant UMO-2014/13/B/HS3/04976) and which was additionally sponsored by the Jagiellonian University in Kraków, the Archaeological Museum in Pozna?, the Polish Centre of Mediterranean Ar-chaeology, the University of Warsaw,and the Patrimonium Foundation, Pozna?. The material from Hornstaad--Hörnle IA was unearthed during the 1983-1993 excavations which were funded by the DFG (Deutsche Forschungsgemeinschaft) within the framework of the DFG Schwerpunktprogramm „Siedlungsarchäologische Untersuchungen im Alpenvorland" (PI: Dieter Planck). The finds from Sip-plingen--Osthafen were excavated within the scope of the project "Das 'Sipplinger Dreieck' als Modell jung- und endneolithischer Siedlungs- und Wirtschaftsdynamik am Bodensee" which was also funded by the DFG (proj. no. 62215951, PI: Helmut Schlichtherle). Excavations at Zürich Parkhaus--Opéra were funded by the Cantonal Archaeology of Zürich, the Office for Urbanism of the City of Zürich, and the Federal Office for Culture (FOC) Switzerland, as were the archaeobotanical analyses of fragment ZHOPE 6949.1, carried out at the Vienna Institute for Archaeological Science (VIAS) at the University of Vienna in 2014. The State Office for Cultural Heritage Baden-Württemberg and the Institute for Botany (210) of the University of Hohenheim funded the international workshop "Ancient beer: multidiscipli-nary approaches for its identification in the archaeological record" held at the University of Hohenheim in February 2019, during which the foundations for this paper were laid. The comparative find no. 252 from Haselbach was obtained from the project „Keltische Siedlungszentren in Ostösterreich" (PI: Peter Trebsche and Stephan Fichtl) funded by the Federal Government of Lower Austria. Funders BIAX Consult and Braxar GmbH provided support in the form of salaries for authors LKM and HK, respectively, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the 'author contributions' section. Neither had the other funders a role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: LKM and HK are paid by commercial companies (BIAX Consult and Braxar GmbH, respectively). This does not alter their adherence to PLOS ONE policies on sharing data and materials.

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