Beer has been a part of human history for many years. Excavations and studies show that barley was malted for beer in Egypt and Mesopotamia as early as the 4th millennium BC. In Denmark, malted barley grain has been found in an Iron Age find from Østerbølle in Jutland. But even though there are grain finds that can be dated all the way back to the Peasant Stone Age in Denmark, there has never been a method that has been able to prove whether barley has been malted so far back in time in Denmark. 

“Archaeological grains can be analysed in different ways, until now the primary method has been species determination based on botanical knowledge as well as looking for characteristics such as signs of germination. In addition, isotope analyses have been made, where you, among other things, can date the findings via carbon-14 analysis or nitrogen isotope analysis, which e.g. can say something about soil and fertilization,” explains Associate Professor Kim Hebelstrup from the Department of Agroecology at Aarhus University in Flakkebjerg. 

Electron microscopy shows the cell structure of the grain

When evidence of malting has previously been found in samples from Egypt and Mesopotamia, but not in Denmark, it has to do with the type of crops that has been grown in different parts of the world. The grain found in the southern countries was mainly hulled barley, while naked barley dominates in southern Scandinavia. And it is significantly easier to identify malting in hulled barley than in naked barley due to the absence of visible indentification markers of malting in this type of grain. 

But a new method has changed that.

“In the malt process itself, the starch granules inside the grain are converted to sugar. This happens when the barley germinates and it is preserved when it is subsequently dried and stored. Our idea was that by using electron microscopy we would be able to see the inner cell structure of the grain. It consists mainly of starch in the form of small granules, and it will be able to give us an answer as to whether the barley has been malted or not, but it requires that the cell structure in the charred grain from prehistoric times is still preserved," says Kim Hebelstrup. 

And the researchers were lucky that the cell structure was preserved even in grain dating back to the Stone Age. Using electron microscopy, they have been able to see changes inside the grain nuclei caused by malting. They have observed how the enzymes of malting in the archaeological grain have eaten into the microscopic starch granules in the same way as when worms eat their way into an apple and make wormholes.

Malted grain from the Iron Age as reference

To ensure that the method works correctly, the researchers have tested it on some of the oldest known malted grain from Denmark. These are a part of an Iron Age find from Østerbølle in Jutland. And here the changes in the starch grains were clear to see. 

"In other words, we now have a method that can give us even more knowledge about the agriculture of the past, especially if they have made malt, and how early they made it," explains Kim Hebelstrup, who has contributed to the project with his expertise in starch and plants. As an associate professor in crop genetics and biotechnology, he has a great knowledge of what goes on at the cellular level in the grain. And the knowledge of the cellular structures has complemented well with the group at the National Museum consisting primarily of researchers Adam Cordes, Peter Steen Henriksen, Mette Marie Hald, and Lasse Sørensen.

Was beer brewed during the late Stone Age in Denmark?

Now a large number of the oldest grain finds from Denmark will be examined to demonstrate malt production in prehistoric time. And the possibilities for this have become extra good, as the Carlsberg Foundation has given the research team a grant to purchase a scanning electron microscope to be placed at the National Museum of Denmark.

"So, now we have to start using the method. Then we can perhaps find Denmark's oldest beer, we can find out if there may have been beer as far back as the Stone Age, and maybe we can also find out if malt or beer played a role in connection with agriculture coming to Denmark. We do not know yet, but we have the method to find out, and it is a big step in the right direction, ”says Kim Hebelstrup, who will continue the collaboration with the National Museum of Denmark and investigate grain that was grown many thousands of years ago.