Monday, 4 January 2016

Making a yeast ring

An essential ingredient in brewing is the yeast. A delicate living fungus, it needs to be cultured, nurtured and kept happy in order to ferment the wort to make beer and develop those interesting flavours in the process. At the end of a fermentation there will be considerably more yeast than when you started. Some of it will be dead or exhausted but some will be healthy and ready to fight again another day. Brewers who brew regularly know that they can crop their yeast - either top cropping or bottom cropping - while the fermentation is vigorous and there will be billions of cells in every millilitre with which to start off the next brew. Just keep it safe from infection, pop it in the fridge until required in a few days time or pitch it straight in to the next brew if there is more than one fermenter and the brewery is going flat out.

If you brew only occasionally - say every few months or even just once a year - how do you keep your yeast until it is needed? It won't keep indefinitely in the fridge. Most of us will just order some fresh or dried yeast from the supplier every time but there are some yeasts that are unobtainable that way, while in the past that simply wasn't an option.

In Norway, they have utilised the natural property of yeast cells that when they dry out they go into suspended animation until woken up again by re-hydration. It happens all the time in nature and it is a godsend for the occasional brewer. Traditional Norwegian brewers have found several ways of achieving the goal of drying a reasonable quantity of yeast, keeping it safe and then re-hydrating it for later use. What they are looking for is some kind of substrate that can be sterilised, has a reasonably surface area, is absorbent, stable, non-toxic and with lots of nooks and crannies where the yeast can nestle.

One solution was to take freshly laundered and ironed linen. This is pretty sterile immediately after ironing and when the yeast slurry is folded away inside the cloth it wicks away excess liquid and allows the yeast to dry out. When dried, the yeast could be picked off in small pieces or sheets and stored in a box or drum until required. Perhaps the most natural solution is to take a small section of a tree branch, the more gnarled the better, possibly with bark on it; boil it to sterilise and then dip that into the yeast slurry and hang it up with a piece of sterilised string in an airy place to dry. It can stay like that indefinitely.

A further development is to take a block of wood, drill lots of holes all over it to provide the nooks and crannies, boil it to sterilise and then, when cool, dip that into the yeast slurry and hang it up to dry. This is called a yeast log in English or in Norwegian it is a 'kveikstokk': kveik being the rather special yeast employed by traditional farmhouse- and home-brewers, who have kept it going for generations, nay centuries.

One of my yeast logs (kveikstokker) well plastered with fresh yeast slurry
from the bottom of the empty fermenter and hanging up to dry.
150 mm x 45 mm x 38 mm
But the design I am blogging about here is the so-called yeast ring. It is a kind of wooden puzzle made of dozens of pegs that slot together rather like a complicated daisy chain and then joined up to complete a circle. There are lots of nooks and crannies, so it can carry a lot of yeast and it also looks very elegant. It's the sort of thing you can make with a saw and a whittling knife in the long winter evenings round the fire in a Norwegian farmhouse. Well that's my romantic view anyway.

Sigmund Gjernes holding his yeast ring (photo: Lars Marius Garshol)
I first became aware of the yeast ring through reading the blogs of  Lars Marius Garshol. He visited a friendly traditional brewer near Voss, Sigmund Gjernes. He uses a yeast ring* (gjærkrans in Norwegian), despite keeping jars of kveik in the fridge. The large jars of yeast will keep for weeks, even several months and are very convenient to brew with. The kveik is allowed to warm, then mixed with some wort to get it going for a few hours and then pitched (at a very high temperature in the upper 30s, almost 40 degrees Centigrade but that is a peculiarity of the traditional brewers who use kveik). Despite having a refrigerator the yeast ring is a good option as a long-term backup. You will have to grow up the yeast to a quantity suitable for pitching into a brew of course.

* I have since learned that the photo above was the first and only time Sigmund has actually used the ring with yeast. Apparently, no one uses them at all nowadays. Aah, what a shame.

Yeast ring made by Martta Pöllänen and discovered on the blog of Hans Haverman
Unfortunately the photographs of yeast rings I had seen were rather low resolution, so it wasn't easy to see the design of the components or how they fitted together, or even how many pegs there were. But by thinking the problem through in three dimensions I had an idea of how it worked. I searched the internet for more images but only came up with one other design (above) made by Martta Pöllänen ( and that was an even lower resolution picture, although the design was more elegant than Sigmund's.

I went to Voss in September 2015 on a mission to taste some traditionally brewed 'maltøl', or more specifically 'vossaøl' as made around Voss in Western Norway (see previous bogs My Trip to Norway parts 1-4). While I did meet Sigmund and he very kindly and generously gave me a couple of litres of vossaøl I never got to visit him at home, nor see his yeast ring 'in the flesh' before my schedule took me back to Oslo. I also visited the Voss Folkemuseum where there is a perfectly preserved set of ancient wooden farm buildings (Mølstertunet) including a brew house but they didn't have a yeast ring on show and though I have inquired since, if they have any yeast rings in the collection, I am still waiting to hear back from them.

In November 2015 I began to think about making a yeast ring like the design by Martta Pöllänen and drew some pegs to scale, guessing at the design and dimensions by taking clues from the photographs. Fingers and eyes of people in photographs tend to be fairly fixed in size, so by using them as a scale I got some idea of the size of the pegs. Sigmund's yeast ring looked as if it had 90 pegs and the design from Martta Pöllänen had 63 (both multiples of 3 I noted). I began to make a few pegs from any old wood I had around, which was cheap pine timber. The photographs suggested to me that the Norwegians used pine.

I had my portable work bench set up in the brewery and was working away with circular saw and hand tools. I was interrupted by a charming couple from Nottingham who were interested in buying some beer. Naturally we got chatting about what I was up to. The gentlemen, whose name was Gerry Gamble, could see that I was making hard work of it by cutting out every peg, one at a time, by hand, cutting slots and whittling with a craft knife. Indeed, it wasn't efficient but I was feeling my way to create a prototype and to find out how it all fitted together. I wasn't worried about speed or efficiency at that stage. I had created half a dozen pegs by then and I could see that by slotting one peg through the back of the previous, they would all join up eventually. What I could not get my head around was how they would join up at the last peg to complete the ring. There would have to be a modified last peg I reasoned but I would solve that problem when I came to it.

This chance meeting with Gerry was one of those strokes of luck that I keep alluding to in my blogs, for it turned out that not only was he retired but was also in possession of a well-equipped workshop and he was keen to use it. Furthermore, he had acquired a baulk of the finest Baltic pine timber that had been taken out of the belfry of an old church. And here he was, exactly at the right moment! He offered to machine me up a quantity of blanks that I could finish off by hand and moreover he suggested that if he made me a jig or template to help me I could drill out the slots accurately and quickly, two at a time. True to his word, about ten days later a parcel arrived containing 70 beautifully made blanks of fine- and straight-grained Baltic pine and a steel jig for drilling. When I lined them all up they looked like the keys of a piano.
Machine-cut blanks in which I have drilled and cut slots.
So over a couple of days at New Year I finished off the pegs, using 70 of them to make a ring on the lines of the design by Martta Pöllänen. On the final peg I shaved the 'beak' down until it just slotted through the tail of the first peg and, due to the curvature of the ring, it stayed in place by shear friction. I used that peg to carry the string, which also ensured that it couldn't come undone. All the pegs available were used in order to close the circle. I think if the tails were thinner - 5 mm rather than 6 mm - it would go round a tighter, smaller circle with fewer pegs (e.g. 63 just like the original). To my relief it was still small enough to go through the aperture in the top of my fermenter and small enough to lay in the bottom of my large stock pot for the sterilisation boil and for beginning the starter when the yeast was re-hydrated. By having 70 pegs, which is not a multiple of three, one has to introduce a twist in order to get the ring to couple-up and that is an interesting feature not seen in the two examples for which I have images: a Norfolk twist, so the speak. If thorough cleaning is required the ring can be disassembled quite easily and put back together again.

Number of pegs :   70 (identical, except for the last one, which has a slimmed down 'beak')
Length of pegs   :   83 mm
Width of pegs    :   16 mm
Height of 'beak'   :  10 mm
Length of 'beak' :   30 mm
Thickness of tail :     5 mm
Slot                   :     7mm x 20 mm
Diameter of ring :  245 mm
Weight of ring    :  256 g

A finished peg with the beak shaped by hand with a craft knife and the corners chamfered.

To assemble the ring keep pushing the tails through the back of the
previous peg and with the beak in the same orientation as the one below.

The finished ring. Note the spiral twist.

Sunday, 3 January 2016

Trip to Norway: Part 4. Drinking vossaøl in Dyrvedalen

Anbjorg was true to her word. The mobile rang. “My brother John says he will pick you up at 7.00 but you have to know one thing about John: he is always late and when he says seven he means, well, maybe more like eight.”

I spent the day eagerly anticipating this appointment. I was to join John Nornes (pronounced Yawn Nor-ness) for an evening at his home to taste vossaøl, the local home-brewed beer from the Voss area in western Norway. I’d been down to town to try to get some small vessels to put yeast into, just in case he had any to spare but the early closing of the chemists shop meant I had missed the opportunity. So I sat around in the comfortable hostel, surfing the net and texting home. At ten to seven I got another call. “Hello, this is John, Anbjorg’s brother. I am running a little late, so I’ll see you at about half past seven”.

I didn’t mind. That this meeting was happening at all was a minor miracle (see my blog, Trip to Norwegian part 1). This was the opportunity I had travelled especially to enjoy and I was going to savour every moment. I wanted to brew a traditional farmhouse ale at Poppyland Brewery, using yeast deposited at the National Collection of Yeast Cultures (NCYC) by Lars Marius Garshol. But I needed to know what I was aiming for and especially what it tasted like.

So here I was, full of one version of vossaøl brewed by the son of Sigmund Gjernes that I had been drinking most of the afternoon: a lowly-hopped sweetish brew, un-carbonated, slightly cloudy and not too dark. Beside me was a nearly full growler of carbonated vossaøl that Dag Jørgensen had given me at Voss Bryggeri: a professionally brewed keg vossaøl, much darker, with a distinctive kick of juniper and a taste like dark marmalade. 

Vossaøl brewed by Yngve Gjernes, son of Sigmund

Vossaøl brewed by Yngve Gjernes, with a note from Sigmund, "Promise, drink every drop of it at once"

Kegged vossaøl at Voss Bryggeri
At twenty past seven I moved outside to enjoy the evening and await John’s arrival. At twenty to eight a small car saloon drew up and a smiling man beckoned me around to the passenger door and soon we were off, making our introductions and heading westwards towards his second home up in his native Dyrvedalen. After a few kilometers we left the shore of the fjord and headed up to a wide hanging valley, lightly populated by houses and farms. We doubled back on a tight bend and there before us was a neat little detached wooden house typical of Norwegian homes around here.

Looking up into Dyrvedalen (Google Earth Street View)
As we approached the door the family came out to greet us. John’s wife and children were curious to see this madman who had travelled all the way from England to taste the local beer. We chatted about school and life split between Bergen and Dyrvedalen but soon John and I got down to the business in hand. I presented him with the growler of vossaøl from Voss Bryggeri. He produced a large jug of dark ale that had been drawn from the tank in the garage. As tradition dictated it was served flat, without bubbles or a head. We talked of how it was brewed, the ingredients, the processes but what did it taste like? Well, it was delicious. Still quite sweet but well balanced, with slightly more hops (East Kent Goldings) than Sigmund’s son’s version but the similarity was there; malty (Maris Otter in this brew) and with a fascinating tang rather like dark marmalade and a light tingle from the juniper infusion. This was great beer and difficult to tell its strength as it was so drinkable but he told me it was 9.2%.

At the dining table with John Nornes and his dark vossaøl
John likes to brew in Bergen with his neighbour Mats Wold and we tried one of his, a ‘Viking Pale Ale’ made with Pilsner malt, American hops (Chinook, Cascade and Centennial) and fermented with kveik. It was great and as you can imagine much more hop forward and characterised by those big citrus hop flavours, less sweet, lighter bodied but excellent flavour. Later on John brought out his Easter brew of vossaøl. It was a beautiful deep red, with no aroma, was drier and had less mouthfeel. It had a fruity (plum) character but overall it was less flavoursome and completely flat. I think that this was a slightly different recipe (it wasn’t Maris Otter malt for one thing) but perhaps this is evidence that vossaøl doesn’t get better with age. It appears that Norwegian brewers get down to drinking it as soon as the ale has stopped fermenting or, in some cases, immediately after they have sacrificed a libation to the spirits of the ancestors.

"Here, this is for you", he said. To my surprise John produced a decent sized jar of kveik, the family yeast that he had inherited from his father and with which he has brewed continuously for thirty years. But I had travelled without hold luggage, and it was too large to get through security in hand luggage. "I think my cousin has something small enough” he said. “He sends milk samples away in some small plastic tubs. If we go and see him you can see his old brewhouse at the same time."

So I gathered up my things and bid farewell to the family and John and I made our way in the dark down the meadow to a group of buildings a short distance below. His cousin Bjorne Røthe quickly found a suitable tub and transferred some of the kveik and handed it to me. Here it was: the object of my desires. Kveik! I held it up and recorded the moment.

The real deal: kveik from Dyrvedalen. John Nornes (left) and Bjorne Røthe.
We discussed brewing and while John pitched his kveik at 36 degrees, Bjorn insisted it should be 37! I am sure it doesn't really matter that much but the whole point is that these Norwegians pitch at very high temperatures that would shock brewers in England and according to the received wisdom would shock the yeast too and if it didn't kill it would very likely produce strange off-flavours. In Norway, it produces a distinctive character that is possibly increased by under-pitching as well (personal note from Lars Marius Garshol).
So why should the Norwegians use such high temperatures? Well the kveik doesn't seem to mind and is happy to start fermenting at these high temperatures. By all accounts it gets off to a quick start and does most of the work in the first a couple of days.

All the traditional brewing techniques I have read or heard about appear to be aimed at avoiding infection by unwanted organisms. The Norwegian farmhouse brewers wash down equipment with juniper infusion; they mash-in with juniper infusion and even strain the mash through branches of juniper and I am sure this takes advantage of the bactericidal properties of juniper oil. They pitch at the very first opportunity. If they don’t have a heat exchanger, this also saves time and reduces the likelihood of wild organisms getting a foothold in the wort. If the yeast is heat tolerant and fast it can begin fermenting before other organisms can grow and then out-compete them if they should appear. When the beer has finished fermenting it will be 8% or 9% alcohol, which, along with some hops, will also safeguard against infection by bacteria. Thus, John says, he has been brewing continuously for over 30 years with the same strain of yeast and never needed to call on his backup yeast.

My experience of growing the starter is that the fermentation is actually more vigorous at around 27C rather than the mid 30s. So I think the kveik tolerates the high 30s but actually prefers the mid to upper 20s. By that time it is going so strongly that it effectively out-competes anything else for the available resources.

Bjorne Røthe's brewhouse was amazing. Located in a separate wooden building, it was illuminated only by a dim yellow electric bulb in the centre of the room. Everything was of wood and the floor was an uneven surface of soil and flagstones. It was difficult to see in the gloom but Bjorne rubbed at a patch on the front of a cupboard. He held his mobile phone to it and in its glow I could make out a date: 1766. On the wall was a reindeer skull with a good set of antlers and in the centre was a raised hearth slab. Above it was suspended an ancient cauldron hanging by chains from a beam. Wooden tubs lined the walls.

In the ancient brewhouse with John Nornes.

The brewing cauldron.

An ancient cupboard dated 1766 and evidence of recent brewing.

It wasn't clear if the brewhouse had been used in recent years but had obviously been well used in its time. What a privilege it was to stand in this ancient brewing space, apparently unchanged in centuries and probably older than the United States of America. I still had the flavour of vossaøl on my tongue and the hair stood up on the back of my neck.

I was getting late by then and John had been very friendly and hospitable but I felt that I should not out-stay my welcome and besides, John's wife had volunteered to drive us back to Voss. I left Dyrvedalen with the distinct feeling that I had made some good friends there, drunk some good ale and I was really really, chuffed that I had a little tub of kveik that I would take back to England and deposit some in the NCYC and brew with the remainder. See a later blog to see how I got on.