Monday 22 January 2018

roasted toasted sprouted barley

Until the Industrial Revolution there was only one kind of malt. So we were told by maltsters at the seminar we attended a couple of years ago. It had been organised by the Orkney Science Festival and was held at the Highland Park Distillery. Only twelve tickets available, so we were very lucky to be there!

Malt has been made using the ancient and traditional techniques of steeping, aeration and floor malting for thousands of years. Grains such as wheat, barley, rye, millet or oats can be malted. Making malt was probably one of the first grain processing techniques, going right back to the earliest grain agriculturalists of the Fertile Crescent, at least ten thousand years ago and maybe more. What is floor malting? Harvested grain is steeped and aerated before being partially germinated. Most importantly, drying the green malt must be done very slowly and carefully. This is how a base malt, known also as diastatic malt today, has been made for generations upon generations. 

This kind of malt is not roasted or toasted at high temperatures.

Why not? Because roasting the malt at too high a temperature destroys the enzymes within the germinating grain. These enzymes are essential to convert starch into sugars later in the brewing process, that is, in the mash tun. Although the scientific explanations of grain germination, the biochemistry and the physiology, have only been understood since the 1960s, maltsters have known the importance of keeping the 'spirit of the grain' alive throughout the malting process. From steeping to kilning, maltsters have known what to do for a very long time. Henry Stopes' classic study of the practices, processes and technicalities involved in making good malt and malting technology (published in 1885) is a book that I repeatedly refer to. In his first chapter there are several descriptions of how malt was made in medieval times and earlier. I especially like this one, where it is clear that the early maltsters definitely knew how to handle the germinating grains:

"the grain was steeped and germinated, by which its spirits were excited and set free; it was then dried and ground and infused in water, when after [it was] fermented."
by Geoponius? cited in Henry's History of England, see Stopes (1885)  

To make good diastatic or base malt you have to do the right things in the right way, using suitable temperatures and having the correct conditions for each stage of the process. Making malt is a craft. It requires specialist knowledge, skill and experience. There's a lot more to it than just sprouting a few barley grains in a jar in the cupboard under the sink, or in a warm place. The maltster's knowledge, experience and skill means that they can steep, aerate and partially germinate very large quantities of grain without it going mouldy or bad.

Modern specialty malts, such as crystal malts, amber malts and chocolate malts are roasted at high temperatures, but these only began to be made around the 17th/18th century. They are a modern technology, used to add colour and flavour to beer. They do not provide fermentable sugars. Roasted, toasted specialty malts came about because of a change in the fuel used to dry the malt. The Industrial Revolution introduced a new fuel: coke. Practices changed from using from wood or straw to dry the malt to using coke, the result being a paler malt than was previously produced.

So, to cut a very long and complex story short, malts began to be roasted and toasted at around the time of the Industrial Revolution in order to make ale and beer the colour that consumers were accustomed to. Specialty roasted, toasted malts are not a technology of the Neolithic, Bronze Age, Iron Age, Viking or Medieval eras.

What has any of this to do with archaeology or archaeobotany?

Well, I've just read yet another paper where the archaeobotanical report incorrectly uses the terms toasted or roasted sprouted barley when considering that the carbonised cereal grains and fragments of grains discovered there could have been malt for brewing purposes. This paper was published in the specialist archaeobotanical journal Vegetation History and Archaeobotany in December 2017. So there is little chance of it being read by a maltster. It's well worth reading because this is some of the best evidence yet discovered for malting. It is a shame that the descriptions of how to make malt, how to mash and ferment into beer are misleading and confused. More on that later. It's possible to contact the author and get a copy. That's what I did. Here's an extract from the abstract:

"Archaeobotanical remains of sprouted cereal grains as well as cereal fragments from the Bronze Age sites of Archondiko and Argissa on mainland Greece, presented here for the first time, provide strong indications for the making of something similar to beer in late 3rd millennium BC Greece, opening up a series of new questions about the recipes followed in this process and their origins."

What about those words sprouted cereal grains? To many people, they suggest growing long bean sprouts, the sort of thing we grew in school in Biology lessons, but that is not what malt is. Malt is grain that has only just begun to grow. The acrospire should be about three quarters of the length of the kernel or perhaps a little bit more. Too much growth and all of the grain starch will be used up and there will be nothing for the mash tun.

This kind of description of malt as toasted roasted barley sprouts has been repeated over and over again in the archaeological and archaeobotanical literature, in excavation reports and elsewhere. The idea that to make malt for beer brewing in prehistory, the grain was sprouted and then roasted or toasted in a very hot kiln is incorrect. However it's a very common explanation. It doesn't seem to be tied to any particular era, I've read papers and excavation reports that discuss sites from the Neolithic to the Iron Age and beyond. They usually say, that is, if malt is even acknowledged as being part of the beer brewing process, that the grain was sprouted and then roasted or toasted to make malt.

In the article on Booze! in National Geographic magazine (February 2017) brewer's malt is described by the journalist, Andrew Curry as sprouted toasted barley grains. Not being a malting or brewing expert himself, he has clearly relied upon information given to him from brewers, such as Martin Zarnkow who he interviewed for this article. Zarnkow has attempted to recreate Sumerian beer on the laboratory bench using malt mixed with unmalted grain and using sourdough as a starter for fermentation. He claims he can make alcohol overnight. It is a strange recipe for beer. 

Incidentally, there are some rather odd recipes for ancient beer around. For example, Professor Patrick McGovern's most recent book, Ancient Brews, uses malt extract (a Victorian invention), specialty malts and other unusual ingredients for an ancient ale. When he was recently interviewed by Beersmith, the Professor acknowledges that he has never actually made a beer from the grain and that perhaps he should try it, for the experience. I'm wondering, how can he be a beer expert when he has no experience of making beer from the grain?

Ancient ale and beer recipes are the subject of another blog, not yet finished and not yet published.

The main point that I want to make in this post is that roasted toasted sprouted barley is not a suitable description of malt, malting or malting technology prior to the 17th/18th centuries AD. It's wrong. Archaeologists and archaeobotanists should read beyond their own literature. They should talk to maltsters and read about malting and brewing science if they want to understand what malt is, how it has been traditionally made and what its' properties are. It's a fascinating subject.


 some further notes ...
I've had some quiet, private and useful feedback from a few people. It seems that those who have no personal experience of making malt or brewing beer from the grain find it very difficult to understand these processes. Some struggle to see, in their mind's eye, how this so-called 'sprouted' barley can be transformed into ale. What happens to it? How is it processed?

I've been told that this film is helpful:

About 30 minutes long, it was made in Norway in the 1960s. The equipment used would have been available in the Viking and Medieval eras, probably also in the Iron Age. It shows some of the traditional, farmhouse brewing techniques. Also, it gives you an idea of how to handle the necessary quantities of grain that must be malted before being mashed and then fermented into ale. 

There is great skill, knowledge and experience involved in making good malt and brewing ale with it. You can get all the sugars you need to ferment into beer from the grain. There is no need to add extra sugars or honey. 

I hope it helps! 


  1. I am not sure this statement is correct: "They [specialty malts] do not provide fermentable sugars." It's true that roasting or toasting tends to destroy the enzymes necessary to convert starches to sugars, so a brewer couldn't mash these malts by themselves (they don't "self-convert"). But nothing is to prevent a brewer from using these malts as a source of fermentable sugars in conjunction with malts that still have sufficient enzymatic power to convert their starch.

    I checked the malt analysis sheets for a number of toasted malts and confirmed that they contain significant "extract" (starches). Specifically I checked Briess "Victory" and "Special Roast" malts, and they contain 75% and 72% extract, respectively. (These are obviously just averages, but they are indicative.)

    In reality, I would not expect primitive malting to yield nearly as uniform a product as modern malting does. Some kernels might get so hot that they can contribute no starches, others might simply lose their enzymes while retaining most of their extract potential (like the Briess malts I mentioned), and others might retain sufficient enzymes to convert the entire batch. This mix of malts may have been more desirable than pure "base malt" for any number of reasons, or it may simply have been infeasible or unduly expensive to make pure "base malt." For instance, to ensure that all the grains had become sufficiently dry, it might be necessary to "overshoot" on a portion of the grain, toasting it.

    So in other words it seems possible to me that people roasted/toasted their malt in antiquity. Of course this doesn't prove that they did so, but I don't think it can be ruled out analytically.

  2. Thanks for commenting. Yes of course, roasted malts can be used in conjunction with base malts. Usually around 10% of the grain bill.

    I'm not sure what you mean by primitive malting - do you mean floor malting? That can be efficient.

    The archaeological evidence for drying harvested grain and malt is the grain or corn dryer, which can dry grains slowly gently but not, as far as I know, produce roasted malts. Unless it burns down. Then it's carbonised and ruined. The design of a corn or grain dryer was to dry the malt slowly, lightly kiln it. The fire is not beneath the grain, the flue directs warm air that passes through the bed of malt.

    I don't think that they roasted malts in antiquity. When you look at the history of floor malting it seems to be that roasted malts appeared in historic times, not in prehistory or antiquity. My point is that, in the archaeological and archaeobotanical literature, all that seems to be mentioned is roasted sprouted barley and that's not diastatic brown malt as I understand it. (merryn)

  3. Just for the record, I do not claim to be a modern "homebrewer," although I have learned a great deal at the sides of Sam Calagione at Dogfish and many other craft brewers here and abroad when we have "re-created" ancient brews based on the available archaeological, chemical, botanical, and other evidence. I am currently working on a project with Martin Zarnkow, and have read widely in the modern beer literature. Still, my expertise lies primarily in the scientific evidence for ancient fermented beverages around the world. You can't do everything!

    My book on Ancient Brews does not pretend to provide "fully" authentic recipes, since there is much we don't know. The "interpretations" there for the homebrewer, which Doug Griffith of Xtreme Brewing (and others) developed, are meant to play with the possibilities and stimulate more experimentation. If you read the book carefully, the argumentation for "authenticity" is laid out.

    If you are familiar with the ancient Egyptian, Mesopotamian, and Celtic evidence, a case can be made for toasting malts in antiquity, e.g., see the article on Hochdorf beer by Hans-Peter Stika referred to in the bibliography and on pp. 151-52 in Ancient Brews. Of course, intensely fired dark malts came much later with the Industrial Revolution.

    Hope that helps to explain how a passing comment on Beersmith should be understood (I have made beer "from the grain," a strange expression), and not deter the interested homebrewer from trying some of the interpretations of Ancient Ales in the book. By the way, I have tried the overnight cold mashing of barley, and it does produce about a 2-3% ABV and tastes reasonably good. I'm not so sure about that beverage having been made by ancient Mesopotamians, because the evidence is limited--perhaps, only at Tell Bazi.

    Dr. Pat

    1. Thanks for your comments Dr Pat. Do you remember, we met at the Beer in Antiquity Conference in Barcelona, 2004? You gave the keynote speech. My paper was on the archaeological evidence for malting floors in the Ancient Near East and Levant, now published as 'the craft of the maltster' and available to download from my Researchgate page. A version was published in International Brewer and Distiller. As you know, my research interest is the prehistory and history of malting technologies.

      I'm surprised that you think making beer from the grain is “a strange expression”.

      In the USA all-grain brewing was how the beer was traditionally made. Maltsters provided the malted grain. Prohibition put most breweries out of business. They turned to producing malt extract, ostensibly for the food industry, extolling its' virtue as a new health food. Some of the malt extract was hopped, which means that folk were using it for home brewed beer. After Prohibition, malt extract was the accepted way of making beer in the USA, both for home brewers and for the big industrial brewing companies. See:

      Making beers from the grain, ie using malted grain instead of malt extract and DME, is becoming popular again in the USA. The 21st Century craft maltsters are producing modern roasted malts to be used as adjuncts in the mash tun. Most of the malt they make is base malt, diastatic malt that provides the sugars in the mash tun. This is the sort of malt that has been made for thousands of years since the beginnings of grain cultivation and processing in the Fertile Crescent. Enzymes in the partially germinated grain become active again in the mash tun and convert all the grain starch into fermentable sugars. No need to add extra sugars, the brewer can get all the necessary fermentable sugars from the malt.

      Base (diastatic) malt is dried slowly and carefully. It is not toasted. That would kill the enzymes.

      Yes, I'm familiar with Hochdorf. There's no evidence for toasting the malt. A fire was lit at the end of the ditch. Wet partially germinated grain was laid on a framework. Warm air would have passed through it, thus drying the malt slowly and gently. On one occasion it caught fire, hence the survival of partially germinated carbonised grains. In Egypt and Mesopotamia the malt was dried in the sun, as described in the Hymn to Ninkasi. Again, no evidence for toasting the malt.

      As I wrote in the post, using words like 'sprouted' and 'toasted' to describe malt in ancient times is incorrect, misleading and confusing.

      By the way, we have also tried Zarnkow's overnight cold mashing of barley. It produced an unpleasant clear liquid with very little alcohol. I fail to see how this laboratory bench experiment can be translated into a large scale production of good, feast grade ale or beer.

      Should you ever visit Orkney, I can show you the brewing sites. They date from the Neolithic, Bronze Age, Iron Age, Viking, medieval up to the modern era.

  4. I agree with Merryn that using the word "toasted" gives entirely the wrong impression to the lay reader, making them think of sprouted barley grains being browned under a grill, and "roasted" is wrong too, since the heat used in drying malt is very far from "roasting", so for those reasons the words should not be used. "Dried by slow, continuous heat" is a much more accurate term. If you look at the stages of the malt here as Reimund Geving demonstrates Norwegian-style home malting, you can see that after six hours the malt is definitely darker, but that's NOT toasting or roasting. Nor, I suggest, is the Hochdorf "malting trench" anything that could be called "toasting": whoever was operating that "maltings" would have had to have been continually raking the drying malt up and down the trench to ensure even drying. "Toasting" is to do with carbonation/caramelisation/maillard reactions, which isn't the primary purpose in drying malt: that's do produce a grain with low enough moisture levels that it can be (a) stored safely and (b) ground.

  5. Thanks Martyn for joining the discussion. I reckon that some people hear the word "kiln" and think that it must be very hot indeed, like a pottery kiln or a lime kiln. A grain drying or malt kiln is quite different. Warm air passes through the bed of grain so it is dried, as you say, by slow continuous heat.

    Thanks for putting the link to your fjord fiesta post. That's a really good one!

    The traditional farmhouse brewers of Northern Europe are using ancient malting and brewing techniques that certainly date back to the Vikings, if not earlier, to the Iron Age and maybe even the Bronze and Neolithic eras.

  6. Merryn (and Martyn),

    Of course, I remember you from Barcelona days, read your articles and BAR book, and corresponded about dung in Neolithic brewing.

    I feel as if we're quibbling over terminology or American/Scottish usage. Perhaps, if you had said grain bill or grist, I would have understood better. Yes, I am familiar with modern malt extracts, and in fact, I will be speaking to our local homebrew community about that, both liquid and dry, tomorrow evening. I will be traveling to Dublin in May and questioning the Guinness brewers about the relative amounts of grain and malt in their brews.

    As to the term "toasting," I wonder how you explain the firing installations shown in the earliest beermaking scenes in the world from the tomb of Ti (see pp. 102-105 of Ancient Brews, or the dark and other speciality beers of both Mesopotamia and Egypt?

    It would be wonderful to visit Orkney. Many thanks for your kind invitation.

    Cheers, Dr. Pat

    1. Hello again! Our correspondence about so called "dung beer" occurred in 2001. Oddly enough, I came across the emails recently when I was going through some old papers.
      I cannot believe that you still think I brewed with animal dung! I did not do this, never have, never will. Thank you for giving me the opportunity to refute this silly, scurrilous news story once again.

      In the summer of 2000 I did a presentation on malting and brewing in the neolithic at a conference on Orkney. I had samples of bere barley, malted bere, wort and some home brewed ale made from bere malt and preserved with dried meadowsweet flowers for people to sample.

      Another demonstration on that day was local potter, Andrew Appleby. He was using cow dung in his clamp firing. I did not use any of his pots.

      Journalist Kath Gourlay wanted a fun news story and so, between them, Andrew and Kath made up this amusing anecdote about dung beer which is entirely untrue. Before I knew it, the story had appeared in several Sunday newspapers, such as The Times, The Observer and The Independent.

      You wrote about it in your book, Uncorking The Past.

      This silly news story did my personal and academic reputation no good at all. I worked for years to try and undo the damage. Here is a short piece in Archaeology; they tried to help me as much as they could to sort the matter and to explain what had really happened.

      I shall look at the Ti beermaking story again. I have read it several times in your latest book, it would help to have an image of the tomb art that you and Sam discuss. Is this possible? Many thanks.

      We don't use extracts or DME in our re-creations of ancient ales. We use crushed malted barley and herbs such as meadowsweet, bog myrtle or juniper. These are the only ingredients.

    2. Hi Dr Pat, I'm not sure why you mentioned the 'dung beer' fiasco. It's an old, absurd, silly news story that caused me some damage at the time. I also hope you haven’t been talking about it in your lectures worldwide, or to other archaeologists and beer researchers over the past 15 years or so. I thought it had been sorted by those emails we exchanged, and by the news item in Archaeology. Another concern is that you referenced my thesis in your first book, Uncorking The Past, when referring to this story.

      If anyone is interested in my research on malt and ale, the brewing process and the archaeological evidence for it you can read about it on Researchgate, where I've put my thesis and published papers. There's also a page on Academia, with a few more things. If access to these pages is a problem for anyone, please do get in touch and I can email copies to you.

  7. Hi Merryn, I regret having followed the lead of the inaccurate reporting in Uncorking the Past by referring to the use of dung in making the pottery rather than the kiln, and implying that it might affect the beer's flavor. Hopefully, the record has now been corrected and I plan to revise that statement in a future edition of the book.
    Concerning the Tomb of Ti, please see
    I have more detailed refs. at work in French if you really want to dig in. The use of bread is a primary consideration...
    Very best regards, Pat

  8. hello there Pat, my apologies for a delay in responding to your comments above. I've been busy writing. So, to clarify things a bit, I've written the next couple of posts on malting, mashing, all-grain brewing etc. There are photos and details of some of our work over the years into ancient ale/beer brewing technologies. I think you'll be interested in following some of the links to northern European farmhouse brewing traditions. You might also like the 'sweet barley cakes' that we made on a hot stone beside the fire. Perhaps this is something similar to bappir or 'beer bread'... The bread that we eat today is, of course, nothing like the beer bread that was made in the past. I agree with you that the use of so-called 'bread' in the brewing process is important, interesting and it must be considered. We have some ideas on that. We are working on it. Keep reading our blog for more on this later this year! with best regards, Merryn

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