big pots: fermentation and storage

Brewing ale in Neolithic Britain - it seems to be a controversial topic among some academic archaeologists. I'm not sure what the problem is with malting and brewing ale in the neolithic era. It could be that few people understand the processes involved in the transformation of grain into malt, wort and ale.

If you have come to this page via the BBC Earth website, or from the Stone Pages, please be aware that the comments attributed to me there are wrong. I have no idea where they came from, other than as a misunderstanding. I hope for a correction in the near future but so far I am not having much success.

Roasted malts, also known as specialty malts, are a feature of modern industrial malting. I'm working on a blog about that at the moment and will post a link to it when I have completed it, hopefully before the Yule celebrations of 2016!

The last few posts have been about explaining the saccharification in the mash tun, where the crushed malt, when mixed with water and gently heated, is converted by enzymes into malt sugars. I've also written a little about lautering, sparging and how to collect the wort.

We've been asked 'why not ferment in the trough. Why go to all the trouble of trying to collect a wort without bits in it?'

Firstly, alcoholic fermentation requires anaerobic conditions. A large vat (1000s of litres) within a building has a blanket of carbon dioxide over the fermenting beer, as in lambic brewing. A small trough (100s of litres) situated outside would have this blanket blown away. Secondly, during fermentation, the little bubbles of carbon dioxide produced by the yeast, stick to the smaller particles and lift them into the froth of the barm. You can see the towering barm in the picture below. It can turn into a really messy monster when it has a lot of little bits in it. After fermentation you would still have the problem of straining or filtering what brew has not been lost to the froth-over. That is a lot harder with little bubbles in it. A bed of husks will not form properly and filtering just doesn't work. 

Inoculating the wort: starting a fermentation
Once the brewer has obtained a quantity of wort by mashing, lautering and sparging, the next stage of the brewing process is the fermentation. Whether you mash in a large pot, a wooden tub with a spigot hole, in a trough in the ground or in a modern mash tun, the wort that you make must be dealt with promptly to prevent infection setting in. Wort does not keep well. Either you boil it, as is necessary with hops, and then cool and inoculate with yeast at the right temperature. Or you can inoculate a fresh wort when it has cooled, and then add the herbs. We found that meadowsweet flowers inhibited the yeast and are better added after the fermentation. To find out more about raw ale which, basically, is beer made from an unboiled wort, I suggest a look at this blog. Raw ale is a huge topic in itself.

fermentation in close up, this is the barm (foam) on a fermenting beer

There are a number of ways of adding the yeast to the wort to start the fermentation. Today, the brewer can add yeast directly, in dried form or as a yeast starter, when the wort temperature is just right. Many modern breweries keep their yeast starter in a fridge. They scoop some of the barm (foam) from the top of the fermenting beer and then store it in a cool place until required. The yeast culture can be kept and used for several months. 

Brewers in history and prehistory could also have used this simple and basic technique, keeping their barm/yeast culture in a cool place. In the 1980s, archaeologists found a medium sized grooved ware pot which had been sunk into the ground in the remains of one of the buildings at Barnhouse, Orkney. The pot, about a litre in volume, had been buried up to its' rim. Analysis revealed that it had contained some kind of 'cereal based mixture', but they were unsure about the pot's function. I think it may have been a barm pot. It was located in a large building, numbered eight by the excavation team and interpreted as a 'temple' or some other kind of ritual building. There were drains as well as many sherds of broken or smashed Grooved Ware pottery, representing pots of about one litre in volume. There was also evidence of feasting and what archaeologists refer to as 'ritual activity', although what that was is not made clear in the excavation report.

I would say that if an archaeologist is looking for a prehistoric ritual activity then the mysterious and magical transformation of grain into malt, wort and ale is well worth considering.

In Norway, Lithuania, Latvia and other places, the tradition of making farmhouse ale survives, with brewers passing on their skills, techniques and knowledge to their descendants. Old traditions of inoculating the wort are still practised in several areas of northern Europe. The picture below shows a wooden yeast ring or kveikering being used to inoculate a yeast starter.

wooden yeast ring or kveikering (photo from the beer blog of Lars Garshol)

Some sources say that the tradition of the kveikering dates back to the 18th century, although I wonder whether the concept might date even further back. It's difficult to be sure because, of course, a wooden object used to gather yeast and start a fermentation would not survive in the archaeological record. In the Viking era, apparently, a stick was used to stir the fermenting wort. This would put yeast onto the stick. Then, if it was kept dry, it could be used to start the next fermentation by stirring a fresh wort. In the Western Isles of Scotland there is a tradition of stirring the fermenting beer with a hazel stick (or wand) which is then hung up to dry and used to stir the next batch of wort, to begin the fermentation.

We did some experiments using a wooden spoon and found that this technique works perfectly.

harvesting barm from the fermentation vessel

barm/yeast drying on the wooden spoon (more photos here)

Big pots as fermentation and storage vessels.
The neolithic era was the time of the 'first farmers'. The earliest grain agriculturalists of the British Isles (c4000BC onwards) were also the megalith builders. They created magnificent stone circles and henges as gathering places for the community. They built stone tombs for their dead and they began to settle down. Associated with the 'first farmers' is the integrated 'cultural package' of grain cultivation, the management of domesticated animals (cows, sheep, goats and pigs) and the manufacture of ceramics. This was the 'neolithic revolution', a different lifestyle to the mesolithic hunter gatherers who had roamed the land for thousands of years previously. At this time in prehistory, the technology for making large stave built wooden vessels (vats, tubs, barrels) did not exist.

How did these neolithic 'first farmers' process their grain? Were they grinding it into flour, to make bread? Were they boiling it, making some kind of gruel or porridge? Or were they making ale from it, by malting, mashing, sparging and fermentation? For some reason, the possibility that such a thing as ale in the neolithic is considered to be a controversial idea by many archaeologists. I'm not sure why. 

Some of the large neolithic Grooved Ware pots might have been used as fermentation vessels. They are perfect in both shape and size. One particularly large Grooved Ware pot found at the neolithic village of Skara Brae, Orkney, was around 30 gallons in volume. Most of the large Grooved Ware pots were around eight to ten gallons. They are found at many ritual and feasting sites of the neolithic, in domestic contexts, for example at Skara Brae, Orkney, and at stone circles and henge monuments throughout the British Isles.

What is Grooved Ware? It is neolithic pottery that archaeologists have defined by its' decorative pattern of grooves and shapes on the exterior. Not all grooved ware has grooves; some of it has fancy applied decoration, with blobs of clay and raised patterns. Most Grooved Ware pots are bucket shaped, with a flat bottom. They are found throughout the British Isles, from Clacton to Orkney and Shetland and also in Ireland. Indeed, this style of pottery was first called 'Rinyo-Clacton Ware'. Rinyo being the name of a site on one of the Orkney islands, Rousay. It was a neolithic village larger than Skara Brae. Grooved Ware was also found on the south coast, at Lion Point near Clacton.

Here's one of Stuart Piggott's beautiful and classic drawings of British Neolithic pottery, showing what some of the Grooved Ware pots from the south coast probably looked like, based upon sherds found during excavations on the Essex coast, at Lion Point.

 

Pottery is frequently found during archaeological excavations. Archaeologists regard it as diagnostic. The discovery and identification of a sherd of pottery gives them a good clue about the date of the site. Neolithic and Bronze Age pottery was not glazed. It could have been waterproofed in several ways, by burnishing or by being sealed with fats, beeswax or milk.

a sherd of grooved ware

Pottery typologies are complex. It's an enormous area of archaeological study and I could not possibly go into every style and type of British Neolithic pottery in this blog. We would be here forever. There's Windmill Hill, Grimston-Lyles Hill Ware, Ronaldsway, Grooved Ware, Unstan Ware, Peterborough Ware, Ebbsfleet and so the list goes on. Most are round bottomed pots, with the exception of Grooved Ware. It took me many months to get to grips with these stylistic categorisations that have been imposed upon pottery of 5000 years ago.

Many bowl shaped pots are interpreted as 'cooking pots'. That seems fairly reasonable. What puzzles me is that whenever archaeologists find a very large pot, or the sherds of a large flat bottomed bucket shaped pot, it is almost always interpreted as a 'storage pot'. I have not yet come across a large pot from the British Neolithic that has been interpreted as a potential fermentation vessel, although some of them have a volume of several gallons and such large pots are often found at feasting sites, for example, at Durrington Walls, near Stonehenge.

If an earthenware pot is to be used to contain any liquid it must be waterproofed. We discovered, in our mashing and fermenting experiments, that beeswax worked very well as a sealant, as did butter and lard.

As a control experiment we tried fermenting mead in an untreated earthenware pot. The fermentation worked well, the room filled with the smell of mead, and the outside surface of the pot was covered in little beads of sticky sweetness. But the final product was disappointingly low in alcohol. It turns out that the alcohol diffuses through the porous pot much faster than the honey solution. This makes an untreated pot pretty useless for creating an alcoholic drink.

Here is a sample of some of the British Neolithic pottery types, as recorded by Stuart Piggott. You can see that there is a wide range of styles. Some have holes in the rim, to secure a covering or lid of, perhaps, leather. Some are deep, others are wide and shallow. I prefer to look at these pots with function in mind, rather than consider only their decoration and style.

Is there any archaeological evidence for the use of large pots for the fermentation or storage of barley wort? 
One of the very best indicators that a pot was used to ferment wort into ale, or for storing the ale, is the identification of beerstone on the internal surface. Beerstone precipitates out of a fermenting barley wort, it looks rather like eggshell. We have a lot of it accumulating on our plastic fermentation buckets and storage vessels.

It takes many hundreds of uses to accumulate a visible deposit of beerstone, but it is a certain proof of fermented wort. Brewers using plastic pipes in breweries often have to clean them of an accumulation of beerstone. It clogs the pipes.

Here is some beerstone from one of our fermentation vessels:

Beerstone has been identified on pots from a Bronze Age site in the Zagros mountains of modern day Iran. At excavations at Godin Tepe a great many pots and jars were discovered, they were stored in the University of Pennsylvania Museum. Subsequent analysis of a yellowish deposit on the internal surface of jars identified beerstone and it is generally accepted as unequivocal evidence for beer brewing. This pioneering paper by Badler, Michel and McGovern, published in 1993, tells the whole story and contains sufficient detail to be able to repeat the tests for beerstone on prehistoric pottery.

I wonder whether any archaeologists in the UK or Europe would consider looking for beerstone on big prehistoric pots? Maybe it is already being investigated. It would be great if this could happen, since this might end the apparent controversy about whether or not a big old pot was used for the fermentation of beer made from a barley wort.

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If you would like to make your own kveikering, here is some more information  and details of how to make one. Brewer Martin Warren of the Poppyland Brewery was so impressed by the idea that he made his own.

My conference paper from 1996 "Neolithic Ale: Barley as a source of sugars for fermentation" can be downloaded from my Academia page, here. 

lauter and sparge

When the brewer has mashed in, he or she needs to separate the sweet wort from the grain husks. This is achieved by lautering and sparging.

It's a crucial part of the beer making process.

The previous blog was about the ancient magic of the mash tun, where the brewer transforms grain starch into sweetness. The saccharification, a process that is driven by the starch converting enzymes in the partially germinated grain, the malt.

At the end of the mash the contents of a mash tun are sweet, with the grain husks mixed up with the liquid. Although the brewer calls it the mash, it has not been physically mashed up, as you would mash potatoes for example. It's more like an infusion, when you put the leaf tea into the pot with hot water, then allow it to mash for several minutes.

In the brewer's mash tun you could be fooled into thinking that the grains are still whole - they look as if they are. But the starchy endosperm is gone, what looks like a whole grain is just the husk with very little left inside.

the contents of our mash tun: pale malt, roasted barley & wort

Lauter and sparge are wonderful words that mean nothing if you have never done it. They are a crucial part of the transformation of grain into ale. Many beer recipes don't use these words. You are just told to 'collect six gallons of wort'. The writer of the recipe assumes that you know how to do this.

Lautering is when you collect some of the wort and then, gently and carefully pour it, or trickle it, through the mash. Keep repeating until the wort runs clear, then collect the clear, strong first runnings. After that, you can begin to sparge. This involves running hot water through the mash to obtain several further gallons of weaker wort. How much wort you collect depends upon how much mash there is in the mash tun and what strength you want the resulting ale or beer to be.

For further details, see the brewer's post about wort which gives specific gravities and more information about wort.

There is a detailed explanation of some of the aspects of lautering and sparging by the brewer and writer John Palmer, from his excellent online book 'How to Brew'. It is,of course, the modern home brewer's perspective and one of the most comprehensive descriptions of how to lauter and sparge that I know of. His next chapter, about the importance of crushing the malt is also well worth reading.

The malt that goes into the mash tun should be lightly bruised, as they say in Orkney. Just enough to break the husk but not enough so that it has the consistency of flour. Too floury and you will have a stuck mash. This means that the hot water will not trickle through the mash and it's almost impossible to obtain the wort. No brewer wants that.

The interesting thing, for me, is how lautering and sparging was done in the past.

Today, a modern all grain home brewer can buy a mashing and sparging bag which sits neatly inside the mash tun. This is how we and many other home brewers mash, lauter and sparge.

First, the mash bag is put securely into the mash tun which has a tap near the bottom. Tie the string nice and tight. Add the required quantity of crushed malt and hot water, leave it for about an hour to mash, maintaining the temperature at around 67 degrees Centigrade. When the mash is done, all you need to do is collect some of the wort in a jug and pour it carefully through the mash. Keep doing this until the wort runs clear. This is lautering. Inside the mash tun, the bed of grain has settled and consolidated, creating a natural filter of grain husks that is held in place by the mesh at the bottom of the mashing and sparging bag.

Then you run off and collect the first runnings; this is very strong wort, very sweet. You can collect further wort by sparging. The more wort you collect the weaker it becomes. Hot water is trickled through the mash and several gallons of wort can be collected in this way. It's not absolutely essential to lauter. It's possible to go straight to sparging. The wort will be cloudy with lots of particles of grain in suspension. Leave it for a while, they will settle at the bottom of the container.

Lautering: we use a jug to collect the wort

Sparging: first runnings, the clear wort is collected

In the days before mashing and sparging bags, how did people collect the wort?

There would be a small hole in the mash tun, either at the bottom of the tub or at the side, very close to the bottom. They used a bed of straw, juniper branches or other fibrous material at the bottom of the mash tun, this would give the grain husks a place to settle and help the grain husks to form the natural filter. The fibrous material would be held down with stones, so that it does not float about in the mash. This traditional method of mashing (they call it masking) and drawing off the wort is described in the malt making and brewing chapter of Mary Scott's book (1967) Island Saga: the story of North Ronaldsay. It was written by her brother William, presumably because he was one of the island's brewers:

" The vat had been prepared beforehand by taking a good handful out from an oat sheaf and spreading it across the tap at the bottom of the vat, and then covering the straw with a stone shaped somewhat like a half moon - the straight side resting on the bottom of the vat and the rounded part fitting snugly to the round of it. The stone would be tilted to an angle of approximately 45 degrees. The stone was to keep the straw in place. 

Masking is then proceeded with using alternative pailfuls of water from the boiler and the first potful that had cooled off somewhat. If boiling water were put on the malt it was liable to stick - that is, it might all set in a gloggy mass, and no liquid could be drawn off. In the breweries I suppose they will put the water on at a certain temperature; there was no thermometer used here, just guess work."

After the mash, or masking, the wort must be drawn off. This is how it was done:

"The vat was allowed to stand for two hours. The boiler was by this time going full swing again ... when the two hours were up it was time to set about drawing off the wort. 

You put a pail under the tap, pulled out the plug, and, if everything was right, the liquid would run off in a beautiful amber stream. It was a great relief when you saw it was running off clear. The first pailful to be drawn off  might have some settlings or groot in it - that is some of the dust or fine stuff out of the malt - so you would tip that pailful back into the vat, for the groot would take a long time to seep to the bottom of the vat again."

I first came across this description of traditional mashing, lautering and sparging techniques when I was doing research in the Orkney Library over ten years ago. At the time I didn't imagine that there might be corroboration or that there are brewers still using these techniques today. Not in Orkney, but in Norway, Lithuania and Latvia. The tradition of making farmhouse ale continues in these, and other, countries and it's possible to meet the brewers and see how they make malt and ale, thanks to this blog by Lars Marius Garshol. He has been visiting them, talking to them and writing about them. It is wonderful research.

Straw, juniper branches and even raspberry canes can be used to help create the filter bed in the mash tun. In this blog, Brewing in Morgedal, Lars tells the story of how he found farmhouse brewing alive and thriving in eastern Norway. The brewers, Halvor Bjåland and Terje Haugen and their apprentice, Bjørn, make ale in the way of their ancestors. I am sure that these methods and traditions go back to medieval times, to the Viking era even. In this blog you can see photographs of the brewing process, including the stones at the bottom of the mash tun holding down the juniper branches and you can see the wort being collected by sparging.

In another of Lars' blogs he writes about farmhouse brewing in Denmark. Here the tradition has almost died out, but not quite. There are some great descriptions and images of lautering and sparging, using hot water and large wooden tubs as mash tuns. I recommend reading through his blogs. It might take you a while, there is a tremendous amount of detail. It's valuable information and an important record of local traditional malting and brewing.

Archaeologists and anthropologists, as well as maltsters and brewers, would benefit from reading, at the very least, some of these blogs. It tells a story that relates to the history and prehistory of making malt and ale in Northern Europe.

Excavations at Must Farm in the Fens of England are drawing to a close. Here, archaeologists from the Cambridge University Archaeological Unit are slowly uncovering a very well preserved Bronze Age village. It seems that there was a fire, the houses and contents burned and have been preserved in wet anaerobic conditions. Archaeologists are finding the remains of wooden buckets, pots with food contents intact and worked wood.

One of the most intriguing and exciting discoveries, for me, was the pot that contained both carbonised grain and some fibrous material. I wanted to include a link to the photograph here, however it's on their Facebook page and it does not seem possible to do that ... a few days later and now it seems to work see here

Why should a fairly large Bronze Age pot contain these two organic substances?

Could it be that the pot was being used in part of the ale making process? Not being involved in these excavations myself, all I can do is speculate. At this moment, I can't think of another reason why the pot contained fibrous material and grain, but there may well be another explanation. Please let me know what you think this might be.

That's all for now, in the next post I shall be looking at how to sparge when you are mashing in a large trough in the ground.