Farmhouse ale styles are known for being messy, sprawling, ill-defined categories to the point where it can be questioned whether they really are styles at all. The Lithuanian style keptinis, however, has a simple definition: it’s made from malts that are baked, often in bread shapes. Keptinis actually means “baked,” just as in the name of the excellent Lithuanian beer snack kepta duona (baked bread), which is bread sticks baked in oil and garlic. Unfortunately, the baking is just about the only point that all sources agree on.
There are two beers that claim to be keptinis on the market today: one is the only beer that Ramūnas Čižas makes, the other is brewed by Kupiškio. Even though I’d visited Čižas and tried both beers I couldn’t really answer the question of how this style of beer is made. After my visit to the library and some volunteer translation work by Remigijus Tranas that changed.
There seem to be four ethnographic papers that to some degree describe the brewing of keptinis (Astrauskas 2008). Unfortunately, I only have a translation of one of them, but that seems to be the most thorough, so I’ll chance a description based on this paper (Petrulis 1975). That paper in turn is based on questioning of just two people, so it’s not clear how definitive it is. In addition, Geir Ove got hold of the 1994 issue of Zymurgy, which has an article by Michael Matucheski on keptinis. And, I got some input via email from Simonas Gutautas of Dundulis. This blog post is the result of me trying to combine all of these into a coherent style description.
Today keptinis is associated with the area around the town of Kupiškis, but it’s clear that it used to be brewed in a much broader area in north Lithuania. I’ve also seen references to baked beer in other Nordic sources, so very likely baked beer has not been a purely Lithuanian thing, but this aspect is still vague.
Beginning of Petrulis’s paper
Looking at the beer itself, the first surprise is that Petrulis claims it was usually made from three types of grain:drooping brome, barley, and oats. Brome is generally considered a weed, but it’s sometimes used as fodder for animals. I asked Simonas Gutautas and he says for keptinis you would (if you were poor) use whatever grains were available, but barley was probably preferred. So while the people Petrulis interviewed used brome, this probably wasn’t a general rule. Matucheski appears to agree with Simonas.
Anyway, the grain is malted in the usual way. Then the malt is mixed with hot water to a thick mash, which as far as I can tell is not left to stand, but then put into the oven at a thickness of 17-19 cm on top of a layer of straw. Some people form bread shapes from the mash, while others just make a thick layer. It should then bake until it’s brown says Astrauskas, while Petrulis says it should be black as coal and crisp. Matucheskis says to bake at 177 degrees Celsius until the top forms a hard crust, usually 20-30 minutes, “but try not to let them brown”. Simonas says “a toasty crust” should form.
After baking, take the baked mash out and crush it with mortar and pestle, then mash it in the normal way together with hops and lime tree bark (Matucheski says lime tree flowers). The mash is left for 4-5 hours, and covered so that it will stay warm. No sour mash, in other words. Then, strain it through a cloth into the fermentation vessel and let it ferment. Neither Petrulis nor Astrauskas says anything about adding yeast, but Matucheski says yeast “was usually added”.
Note that there is no boiling, so this is a raw ale.
A mug full of keptinis
Petrulis says you’d use 1 pura of grain for 125 kvortas of water. That is 70 kilos of malts and 102 liters of water. The amount of hops would be depending on personal taste. Matucheski says for 19 liters of beer: 1 kg pale barley malts, 2 kg rye, and 2 kg oats, giving an original gravity of 1030 and a final gravity of 1010, which means 2.6% alcohol. That sounds very low. The two commercial beers are 5.2% and 5.7%.
According to Petrulis and Astrauskas keptinis is brown-black, with a sweet-sour taste, and “thick, sticky, heady”. (Doesn’t sound like 2.6% to me.) Simonas says it should be “reddish brown, rich in dextrines, full-bodied, sweet in taste and hoppy.” He agrees there could be some acidity from the toasted malts. Matucheski says it’s “gently sweet-sour” at first, then growing more “lactic” with time. Matucheski suggests using Belgian wit yeast, which might not be a bad suggestion, as Lithuanian brewers would use family yeast. The commercial variants are not sour, so I don’t think keptinis should be considered a sour style.
Using a home-brewer’scalculcator, if I plug in 70 kilos of chocolate malts and 102 liters of water, assuming 70% efficiency (probably a bit on the high side) and 75% attenuation, I’d get an OG of 1120 and an FG of 1030 for 11.8% ABV. These figures are very rough, but probably much closer to the actual beer than 2.6%. At a guess, I would assume typical ABV would be around 8-9%.
According to Simonas, making keptinis requires a large oven (for typical farmhouse batch sizes) and a lot of time, so it’s not easy to find any more. He implies there are still people other than Ramūnas Čižas who brew it. He also says Dundulis may brew a keptinis this year. I really hope they do.
And so we end as we began: although the basic definition of keptinis is firm enough (baked mash with straw, wort unboiled) everything else seems to vary wildly. A true farmhouse ale, in other words.
Alus, Juozas Petrulis, in Kraštotyra. Vilnius, 1975. P. 237-248. Translated for me by Remigijus Tranas.
Per barzda varvejo, Antanas Astrauskas, Baltos Lankos, Vilnius, 2008. ISBN 978-9955-23-141-7. Parts translated for me by Elma Caicedo.
KeptinisAlus, Lithuanian Baked Beer, Michael Matucheski, Zymurgy – Special Issue: Traditional Beer Styles 14, 1994-1. Based on Markuza-Bieniecka (below).
If you could help me in any way to get hold of these, in whatever language and in whatever form, that would be deeply appreciated.
Chłodnik znad Niemna: kuchnialitewska by Biruta Markuza-Bieniecka, Watra, 1989. ISBN 8322502354. Thanks to a helpful reader on Facebook I now have this book.
Per barzda varvejo…, Vacys Milius, in Mokslas ir gyvenimas, 1969, nr 2, p 51.
Aludaryste Šiaures Rytu Lietuvoje, Dagys Viktoras, Etnografiniai tyrineji- mai Lietuvoje 1979 ir 1980 metais. Vilnius, 1981. – P.36-39
Keptinis is a little-known Lithuanian style of beer where the mash is baked in an oven. The first farmhouse brewer I ever wrote about was keptinis brewer Ramunas Čižas. A few years ago I put together a description of how to brew keptinis based on ethnographic sources. Martin Warren followed my instructions, but ended up with just black, unfermentable water. So when Simonas invited me to come to Lithuania to see keptinis being brewed, he didn’t need to ask twice.
The Jančys family lives in nearby Utena, but often visits their farm in Vikonys, in north-eastern Lithuania, where they come from. And they still brew keptinis in the old way. The brewhouse is a small brick building on the farm, where Vytautas Jančys, who owns the farm, has built a brick oven specifically so he can brew keptinis. The art of brewing keptinis is something he learned from his father and grandfather, so he’s a real farmhouse brewer. He used to also make his own malts from barley, dried on top of the oven, until about a decade ago.
Starting the mash. Ignas on the left, Vytautas on the right
When we arrived, they had gotten the fire going, and were heating the brew liquor. Outside, in the yard, they’d set up the mashtun, and were getting ready to start mashing.
Vytautas poured a sack of pale malts from Viking Malts in Panevežys into the tun, then added buckets of boiling hot water while his son Ignas stirred the mash. They were using water, not juniper infusion, because this was Lithuania, not Norway. Vytautas kept adding water, and eventually started lifting the mash paddle, staring intently at the drops running off it. Then he would add some more water, then repeat. Finally, he was satisfied. Now they could pack up the mashtun and let it stand.
Judging the mash
But I’d seen no thermometer, so how could he know this was the right mash temperature? I went over to check with my own thermometer. It showed 65C. Simonas saw my surprise and explained to me what was going on. Since Vytautas was using boiling water the temperature of the water was always the same. So if he could hit the right ratio of water to malts, the temperature of the mix would also be roughly right. And this is what Vytautas was doing when he was staring at the paddle: he was judging the ratio of water to malts.
Now the mash needed to rest for an hour, so there was a pause.
Once the hour was up they started scooping the mash out of the mashtun and into metal boxes. These boxes are an innovation that Vytautas has introduced. In older descriptions and ethnographic videos the mash is formed into bread-like chunks where straw is used to help them stick together. The boxes are easier to use since they prevent the chunks from falling apart.
The mash boxes on top of the oven
Vytautas carried the four boxes in and put them on top of the oven. Then he used a shovel to remove the still-glowing embers from the oven. Putting on a plexiglass mask and big gloves he then put the four boxes into the oven, where they would bake for three hours. How hot the oven was I don’t know for certain, but clearly very hot. Simonas thinks the temperature is about 350-400C. This is at the beginning, of course. The fire has been removed, so the oven will slowly cool over the course of the three hours.
Putting the mash in the oven
Now there was another long wait, so Vytautas took us down into his cellar, where he keeps the beer. The June sun was hot outside, but down here in the cellar it was so cool it felt cold. The beer was stored in stainless steel kegs. Traditionally, people would use wooden casks, of course, but these are much harder to work with.
And there was another reason to prefer steel.
Pouring the beer
Vytautas put a plastic bucket under one keg and started to pour. Into the bucket ran what looked like porridge. The pressure in the keg was so high that what came out was pure foam, and we had to wait a good while before the foam turned into beer that we could actually drink. This is normal and traditional for Lithuanian farmhouse ale in general. Kegging the beer at the right moment to have enough CO2 in the cask, but not so early that the whole thing explodes is quite tricky, and serving the beer from wooden casks with primitive taps was also non-trivial.
The bucket was carried back up in the sunshine, poured into a ceramic mug, and served. The beer was deep dark red, nearly black, with a tiny beige head. It was quite sweet, with a massive flavour of toast, caramel, and earth. Very round and mild in the flavour, like a less roasted porter or a more toasty or caramelized brown ale. What was most impressive was the depth of the flavour, and at the same time how rounded and mellow it was. Deep notes of caramel and coffee lingered for a long time.
Serving the beer
It was a deeply impressive beer, and although this was a year ago, I still remember that massive earthy, toasty caramel flavour quite vividly.
While the mash was still baking they started preparing for the lautering. Ignas brought out wooden spiles of alder wood, which were soaked in water so that they wouldn’t float up and ruin the filter. Vytautas took us to the barn where a huge plastic bag of straw was hanging under the ceiling, so that the mice woudldn’t get into it.
Originally, they used the classic Lithuanian wooden lauter tun with a hole in the bottom and a long rod for opening and closing the hole. However, it’s a lot of work to keep these free of leaks and completely clean, so Vytautas has had a stainless steel replacement constructed. They put the wooden spiles on the bottom, then the wheat straw on top.
The baked mash
Now it was time for the mash to come out of the oven. The top of the mash was covered in a hard, dark brown crust. Some of the liquid had boiled over the side of the box, run down the side, and congealed in a hard mass at the bottom. I broke some bits off the top crust and tasted them: massively sweet and toffeeish, with notes almost like honey. They actually tasted like really sweet and good cookies.
And now I realized what was going on and why Vytautas’s beer had tasted so different. This is a dark beer made with pale malts, where the colour comes from the baking of the mash. In normal dark beers, the colour comes from drying the malts at high temperature. The heat makes the starch and protein in the malts go through maillard reactions, producing the colour and the roasty flavours. But in this beer it was the mash that had been baked. What went through the maillard reactions was mostly sugar, not starch. So of course the flavour wouldn’t be the same.
This is actually quite stunning.
Schwarzbier, porter, dunkel, stout, and all the other blackish beers are made from toasted starch, but keptinis is made from toasted sugar. It’s a different kind of dark beer. And, as the beer we’d tasted showed, one that could be really, really good. To make a proper keptinis you should really use Lithuanian malts and yeast, and not boil the wort, but the baked mash concept can be used to make many kinds of beers, not just a classic Lithuanian keptinis.
Breaking the crust
Once the lauter tun was prepared, Ignas took a large wooden spoon and started breaking up the crust on the boxes. Then the fairly dry mash was scooped out on top of the straw. Ignas then got hot water in plastic buckets, and poured it on top of the mash. They let it stand for about 20 minutes, then let the dark brown, blackish wort run off slowly into a porcelain bowl.
Wort coming out
Meanwhile, they were boiling hop tea in a small pot. Keptinis, like all other Lithuanian farmhouse ale, is raw ale, so in order to get alpha acid out of the hops they are boiled in water. This is a simple solution that doesn’t require a big kettle and saves a lot of energy. The little pot reeked with lovely hop aroma, and after half an hour or so the hop tea (in Lithuanian, “apyny arbata”, literally hop tea), was ready. They used just bittering hops for this beer, but they told me that if you want more hop aroma you can put some of the hops in cold water to draw out the aroma.
Once the wort had been run off it was cooled with cold water from a garden hose, and poured into the fermentor. The Jančys family no longer have their own yeast, and have been using commercial yeast for the last 30 to 40 years. Before that they did have their own.
And with that they were done. Within a few days the beer would be finished fermenting, and transferred to cask.
For me this was quite an experience, to see a completely new type of brewing process. Today, keptinis is an ultra-obscure style of beer, made only by a few farmhouse brewers in north-eastern Lithuania, and by three commercial breweries. One being Ramunas Čižas, the other two being Dundulis and Kupiškio.
Of course, keptinis is not the only oven-baked style. This must have been quite close to how the Seto people used to brew. And, as it turns out, the full story is a good bit bigger than just the north-eastern corner of Lithuania. The summer of 2017, it turned out, was the summer of oven-baked beer.
We’ll dive into that story over the next few blog posts.
The church in nearby Andrioniškis
The recipe is for 130 liters of beer, which is what they usually make. 50 kilos of pale malts. Mash in at 65C, then let the temperature drop to 58C over an hour. pH at the start of mash: 6.1.
Then put the mash into an oven, where we think the initial temperature should be 400-350C. Make sure there is a good amount of water in the mash. Let the temperature drop over three hours while the mash bakes.
Take 120g bitter hops (14% alpha acid) and 50g aroma hops (5-6% alpha) and boil them for 30 minutes in 2 liters of water. There was no very clear aroma of hops in the beer, so some noble hop will probably work best.
Then lauter in the usual way, cool the wort, then pitch. They have used both modern dry yeast (probably Safale S-04, 19-25C, 2-4 days) and #16 Simonaitis (24 hours). To be honest, the yeast was not very prominent in the beer I tasted, so something fairly neutral should work. This beer isn’t really about the yeast profile, anyway.
The tricky part here is to judge when the fermentation is sufficiently done, and then transfer to closed keg where it should work up natural carbonation. If you keg too early things can blow up, and if you keg too late you’ll get flat beer.
In older times it was custom some places in Lithuania for people to ask their neighbours over to help judge if the time had come for kegging. If they decided it had come typically everyone would be served beer (kind of like oppskåke) and a party might well develop.
Obi110 was on end of support with no firmware upgrades. On November 1 2017 Google Voice changed certificates and Obi110 failed with ” Backing off” Connection error.
Initially thought as DNS Server issue and tried all and when support refused any firmware updates for Obi110 to fix the certificate issue, I noticed a SIP alternative using a third party provider for incoming calls in the obhi forums. It is an although a puny $6 one time charge, not sure how long this will last, I decided to find an open source solution for running own SIP Pbx. Googling resulted in Asterisk PBX solution and I had a spare raspberry pi w ( bought @Mircocenter for $5) that I could use.
First, it will ask you to enter a password for admin and an admin user will be created.
Using Menu -> Applications–> Extensions create a new PJSIP Extension. (Don’t forget to Submit and Apply config to save )
Using Connectivity-> Google Voice (Motif) configure Gmail Voice. In Gmail security, you can create a new app password and then use this app password here. Also, make sure Add Trunk checkbox and add outbound routes is enabled.
Once you submit and apply. you should see a connected status as below.
Open the outbound route created and remove the defaulted route password. Also, move this over the default Star Communication outbound route.
Add a new Inbound route using Connectivity–>Inbound routes ( in the DID Number add the GOOGLE Voice number without any formatting like 2222332323. Also, add set destination by selecting an extension that we created before.)
Test using Iphone or Android phone( Optional)
Download Zoiper SIP Softphone and add the extension and call any phone to see if the PBX is using the google voice account.
Here are the steps to configure Obi110:
use instructions from https://wiki.freepbx.org/pages/viewpage.action?pageId=4161592.
in the obi config ip, change the Phone port Primary Line in the physical interfaces to use SP1 Service.
Reboot the Obi110 and check SP1 Status. It should show
Now you should all set to receive and place calls using your phones.
For many brewers, water chemistry is treated as the last frontier of homebrewing. Oftentimes, it is ignored or at least not something homebrewers want to think about. The old adage “if your water tastes good, it’s fine to brew with” may be repeated, and believed. The brewer may work on refining recipes and take great pains to provide fermentation temperature control, but ignore the water used in brewing.
This is a mistake because the largest component of beer is the water. Managing the pH of the mash and the flavor contributions of the water can take a good beer to a great beer. While it’s true that poor tasting water will make poor tasting beer, the inverse is not always true. Great tasting water out of the tap may not be well suited to brewing. Additions to the water by the water supply company such as chlorine, or the more stable form called chloramine, keep your water supply safe for drinking but chlorine can negatively impact the flavor of the beer. In some areas, the water out of the tap may be high in bicarbonate or iron which can also negatively impact your beer. If you wish to not delve into water chemistry at all, it is advisable to use reverse osmosis water from the water dispensers at grocery stores or distilled water as it would be a blank canvas to start with. Even so, better beer can be made with paying attention to a few water additions and mash pH that will be discussed in this article series.
Where to Start With Brewing Water
Getting a water report from your water company, if using municipal water, is a great place to start. They should have all of the information available, but you may not get all of the information you need from them at first. They are required to test the water for safety, and will report contaminants and pesticides, but will not always give you the components that brewers are looking for in a water report. You can ask brewers around you about the water, but often the easiest way to get a report on what you need is by ordering a household minerals test from a testing company. If you have a well, this is likely the only way to get a report. One of the dangers will be dabbling with brewing water is to add items per a recipe without knowing what you are starting with, so the report is crucial before beginning. A popular company is Ward Labs, but there are others out there. A basic test should run under $35 for what you need. You will require sodium, calcium, magnesium, sulfate, chloride, bicarbonate, and total alkalinity.
It’s also important to find out if your water company uses chlorine or chloramines for disinfection of the water. In order to use any water for brewing, this is a steadfast rule: the water must be chlorine free. Chlorine will off-gas and/or boil off, but chloramine is a more stable form of chlorine and will not easily boil off. It can be removed via Campden tablets (potassium metabisulfite) easily. One tablet crushed and dissolved into 20 gallons of water and stirred well will remove chloramine (and chlorine) in most cases. Removing the chlorine, or purchasing reverse osmosis or distilled water should be the first step in dealing with water.
The results from your water test will give you the ion concentrations in parts per million (ppm) or mg/l. These minerals are important for brewing water, because they can affect the suitability for use in brewing and have a flavor impact.
If you have iron in your water (look for discoloration in plumbing such as rust spots), it is generally poorly suited for brewing as it is detectable in very small amounts in the finished beer as an unpleasant metallic or even blood-like flavor. Iron should be under 0.1 ppm in the water. If you have sulfide flavors and aromas in your raw water (rotten egg-like smell), it will not be suitable for brewing. If you have some sediment, a filter will often help. Just be sure to send the water after filtering for testing if that is what you plan to use.
The major mineral ions will we be working with are as follows:
Calcium: Calcium is the primary ion that determines the hardness of the water. It helps with lowering the pH during mashing, facilitates precipitations of proteins in the boil (hot break), enhances yeast flocculation, and assists in preventing beerstone. Many lagers are made with very low levels of calcium, so it is not required but can be helpful in the amounts 50-100 ppm.
Magnesium: Also responsible for providing hardness to the water, magnesium can provide a sour/bitter flavor to the beer in amounts of 30 ppm or more. It has a laxative effect in much larger amounts. Malt provides all of the magnesium required for yeast health, so it is not required as an addition unless adding sulfate in the presence of a high calcium level (using Epsom salts, or MgSO4).
Sulfate: Sulfate is the ion that is used to accentuate hop bitterness by enhancing the dryness of the finish. Additions are normally avoided in continental lagers or only used in small amounts, often 30 ppm or less. In most ales, the ideal amount is 30-70 ppm. For highly hopped beers, the desired sulfate level may be much higher: 150-300 ppm for IPAs or west coast APAs. That amount will make the finish seem more crisp and dry. If using 150 ppm or higher, the chloride level should be under 50 ppm to avoid a “minerally” finish to the beer.
Chloride: Chloride accentuates a fullness or “roundness” of flavor in the beer, enhancing the malt sweetness. It is generally used in the 40-100 ppm range in many beers, but in the New England IPA style, the chloride is often over 100 ppm, up to 150 ppm.
Sodium: Sodium rounds out the malt flavors, and can be used in modest amounts (under 150 ppm). A higher concentration can make the beer taste salty, and having a high sodium combined with a high sulfate level can create a harsh bitterness. It is generally recognized that keeping the sodium at 0-60 is a safe bet. Using brewing water sourced from a water softener is to be avoided.
Bicarbonate: Bicarbonate plays a huge role in water chemistry for brewing. It raises the pH of the mash, so should be kept under 50 ppm for pale/light colored beers. An amber colored beer could use a bicarbonate amount of up to 150 ppm (depending on the grain bill). A very dark beer with roasted grains (like a stout) could easily go up to 200 ppm or even a bit more, as more bicarbonate is needed to balance the acidity of the dark roasted malts. As such, there is no ideal range for mashing water except that what is needed to achieve an appropriate mash pH. In sparge water, low bicarbonate water is desired to avoid tannin extraction from the grain. This will be discussed at length in our next article on water and mash pH.
The common brewing salts are gypsum, calcium chloride, Epsom salts, chalk, sodium chloride, and baking soda. These are available at the homebrew supply store, or can sometimes be found at your grocery market.
Gypsum (CaSO4 or calcium sulfate) is used in brewing to bring calcium and sulfate to the water. This can reduce the mash pH, in a small amount as can calcium chloride.
Calcium chloride (Pickle crisp or CaCl2) is used to add calcium as well as chloride, and Epsom salt (MgSO4 or magnesium sulfate) is used for the magnesium and sulfate contribution. Plain old non-iodized table salt (NaCl2 or sodium chloride) brings sodium and chloride to the table.
Chalk: (CaC03 or calcium carbonate) has been traditionally used to raise mash pH in cases where it may be needed, but it doesn’t dissolve well without extraneous measures and is to be avoided in general.
In those rare cases where the mash pH should be raised, baking soda (NaHCO3 or sodium bicarbonate) is most useful.
Lactic acid or phosphoric acid is the most common acids used to lower the mash pH if needed.
A helpful comparison to brewing salts may be seasoning salts in cooking. Just as making chicken soup with a great recipe and fresh ingredients can be improved with a bit of salt or some bay leaf, a great beer base can be improved with a bit of tweaking of brewing salts. Too much salt in the chicken broth can ruin the soup, however; and too much of a brewing salt can ruin the beer. Using more conservative additions with the “less is more” idea is a great way to approach adding brewing salts to your homebrewing repertoire. You don’t want a “minerally” or harsh beer in the end after all your hard work!
There are brewing spreadsheets and books available to help you decide where to target your ideal concentrations of those ions, and Brewer’s Friend has both a basic and advanced water calculator to help you reach your goals. We have given you give a range, and it is recommended to stay at the lower end of the range until you know what you like. You can always add more next time, but you can’t take it out. One pitfall that many brewers fall into as they delve into water chemistry is finding a water profile from a historic city and set that up as a target. That can be problematic, as it may not be what the breweries themselves actually used, as they may have preboiled the water to drop the bicarbonate or used water from another source. If a profile seems to have very high numbers, and you’d still like to make an authentic London porter, dig a bit deeper into what the breweries in that area did with the water before brewing with it. Brewing water with less than your ideal ion targets may seem a bit bland (think of the chicken soup seasoning analogy) but won’t be undrinkable as it would be if you add far too much of a good thing.
A good way to see what the brewing salts may do to your beer is to try it out. Pour a pint of your beer, and add a dash of table salt to it to see what chloride brings out. Next time, add some gypsum, to see what that brings to the beer.
If you are just starting in water additions, you can get by with gypsum, calcium chloride, baking soda, and lactic or phosphoric acid. We will discuss using those items as we discuss mash pH and delve deeper into water chemistry in the next article.
Lithuania has one of the most interesting beer cultures on earth, but it’s a beer culture that is almost wholly unknown outside the country itself. This guide explains what is so special about Lithuanian beer and helps you choose the right places to go and the right beers to drink.
I’ve traveled to Lithuania a number of times over the last four years to learn as much as I can about Lithuanian beer, and this book summarizes what I’ve learned. It describes the various styles of beer made in Lithuania, the main breweries, and where to find the beers. It also gives some cultural, linguistic, and historical background.
Parti-Gyle brewing is a method for making more than one batch of beer from a single all grain mash. It offers tremendous flexibility since you can brew two beers of different gravities, and also add different hops and yeast to create distinct beers from one brewing session.
Parti-Gyle brewing is not a new method. The method goes back hundreds of years, and many modern sub-styles are examples of light and heavy versions made from a single mash. Examples include the various weights of English and Scotch Ale, various grades of Bock, and even variations of Trappist ales. In the 1700’s and 1800’s it was very common to create a strong beer from the first runnings of the mash and a lighter common beer from the second runnings of a mash.
The Parti-Gyle Method
The standard method for Parti-Gyle brewing is to make two beers from a single mash. Typically a fairly high gravity beer is made from the “first runnings” of the mash, and the second runnings are boiled separately to make a lighter beer. Often different hop additions, boil additions and yeast are used to create distinct styles from the two runnings depending on the brewer’s preference.
Estimating the Gravity of Each Beer
When designing a parti-gyle beer, one is usually concerned with gravity and color of the two beers being created. This is important for determining how much grain is required for each beer and also how much liquid to run through each to achieve a target boil gravity. The rule of thumb for an average mash is that 2/3 of the gravity potential is in the first 1/2 of the runnings. This is due to the fact that most of the high gravity wort comes in the first third of the lauter.
One common parti-gyle split is 1/3 volume for the first runnings and 2/3 volume for the second which results in a first batch of beer that has twice the points that the second batch will have. So for example, if the total mash had an estimated original gravity of 1.060, we would expect the first 1/3 to have a gravity of 1.090 and the second to have a gravity of half the points or 1.045.
For a 50-50 split by volume, with half of the wort in each batch we get a roughly 58% of the gravity points in the first batch. So a 1.060 overall batch OG would translate to a 1.070 first runnings and 1.050 second runnings, with both of equal size.
Estimating OG for Split Batches
To perform these calculations yourself, start with the OG estimate of the mash runnings using conventional methods. This can be done using the method described here, except you use the mash efficiency and total lauter volume instead of the overall brewhouse efficiency and overall batch volume to get your mash OG estimate.
Once you have the OG estimate for the overall batch, get the number of points by subtracting one and multiplying by 1000, so 1.060 becomes 60 points. Next we use the following to calculate the final number of points in this fraction:
So if we look at a 1.060 total gravity estimate with a 1/3-2/3 volume split which has half the points in each runnings we get 60 points, 0.5 as the points_fraction and 1/3 or 0.333 as the fractional volume:
Number_points_runnings = (60 * 0.50 / 0.333) = 90 points or a gravity of 1.090
Using the same equation, you can come up with an accurate estimate for the gravity of each of the runnings based on the original gravity of the overall batch.
It should be no surprise that the color of the two batches in a parti-gyle will be darker for the first runnings and lighter for the second in most cases. Calculating the actual color for a regular beer is described here, and is based on the Malt Color Units (MCUs) which are simply the sum of the pounds of malt times their color for all grains in a batch.
Looking at the examples above – a 50-50 volume split has about 2/3 of the gravity in the first runnings and 1/3 in the second runnings. The malt color units follow, so about 2/3 of the MCUs will be in the first running and 1/3 in the second. So if you calculate the overall Malt Color Units for the total batch (sum of the pounds of malt times color of each malt), you can multiply it by 2/3 or 1/3 for each running and then apply the Morey equation to get the color estimate for each of the runnings. Here the OG_FRACTION refers to the 2/3-1/3 OG split so you would apply 2/3 to the first runnings and 1/3 to the second:
Since the Morey equation is not linear, you will see a larger color difference for a parti-gyle beer when working with lighter beers. So for a very light beer and a 50-50 volume split, the first runnings will be almost twice as dark as the second runnings. However as the beer gets darker the difference will be smaller – to the point where the second runnings of a Stout beer might have no perceivable difference in color from the first.
After the Mash
Once you have mashed your parti-gyle beer and taken the two runnings, the rest of the brewing process is the same as with any other beer. Obviously the two runnings are boiled separately so you either need two boil pots and heat sources or a sterile way to store one of the runnings for a few hours while you boil the other.
One of the great features of part-gyle brewing is the ability to change the character of the beer in the boil and fermentation. By adding different hop additions, yeast, spices or steeping additional grains prior to the boil (much like an extract brew) you can dramatically change the character of the two beers produced. With a little imagination you really can create two distinctly different beer styles from a single brewing session.
For design purposes it is usually best to treat the two runnings as separate beers at this point, and the usual rules for estimating bitterness, final gravity and fermentation apply. The design possibilities are nearly endless. You could create a strong ale and bitter, a wheat bock and weizen, a brown and pale and many other combinations from a single mash.
I hope you enjoyed this week’s article and decide to make your own parti-gyle brew in the future. Thanks for dropping by, and please subscribe to my blog or podcast for more great articles and sessions on brewing beer.
Sahti is the traditional beer of Finland. The popularity of the drink waned after the wars, obviously the prohibition of 1919 – 1932 didn’t help. Today, sahti enjoys a small-time revival on the craft brew bandwagon, even on a commercial scale. But at its roots, sahti is a farmhouse ale, a living beer, a real ale if you will, made to be consumed within weeks from brewing. It’s also a true craft beer: handmade, no modern equipment, a wood-fired cauldron, the senses of the brewmaster our only gauge. To taste the tradition, we will join a sahti mage on a brew day in Joutsa, Eastern Häme, Finland. But first, let’s look at how it all comes together.
Sahti has a relatively short history of writing: the earliest written reference dates back to 1792 (EU). The method itself is ancient, of course, passed, like all crafts, from a master to apprentice: “the brewing instructions have probably been handed down from generation to generation for thousands of years”. More recently, sahti has been granted the TSG protection status of the European Union. Says EU:
“a traditional, slightly cloudy, strong beer produced by fermentation. It is neither pasteurized nor filtered and the fermentation is left to run its course, so it is drunk fresh. The original gravity of the wort is at least 19 °Plato and the alcohol content varies between 6 % and 12 % by volume. The pH is less than 5. The colour varies from yellow to dark brown depending on the raw materials used. Sahti is cloudy because it is unfiltered. Because of the high residual-sugar content fresh sahti is slightly sweet tasting.” (source)
Although the TSG status only covers the method of brewing, real sahti is Finnish. Farmhouse ales exist across the beer belt, of course, and cousins of sahti have survived on two islands of the Baltic Sea: dricku in Gotland, Sweden, and koduõlu in Saaremaa, Estonia.
In the Sauna
We will brew in the sauna, which has traditionally doubled as the brewhouse. In the olden times, sauna was also the malt house, the smokery for Finnish palvi meats, and a place to give birth, among other uses. After WWII, many people lived in saunas for a while as nothing else was left. We’re the lucky ones to get to only relax (and brew) in sauna.
We brew sahti with a wood-fired oven, with a wooden spatula, and a wooden trough made of juniper. Little has changed since metal vessels and store-bought yeast came into use a century ago. No scales, not a temperature gauge in sight, ominaispainomittari (a hydrometer) too difficult even to pronounce. The only nod towards the modern way of life is the electricity to power the lights.
The brewmaster will test the temperature with his finger, judge the water-to-grist ratio by the looks, decide water additions based on how the color is developing, sparge until it feels right. It’s not hard to imagine the brewmaster was a sort of a mage to people who didn’t know of saccharification; who couldn’t possibly understand micro-organism such as yeast. Persons capable of changing water to alcohol have been known to enjoy a god-like status before.
When everything was still made by hand, the brewer left a sack of cereal in a stream to germinate. The malt was dried in a riihi, the smoky drying barn. Modern malt for sahti is pale and not smoky. The homebrewer will purchase a sack of malt and supplement it with raw cereals:
“Sahti is traditionally prepared from raw materials including, in addition to malted barley, other cereal malt and cereals (rye, barley, wheat, and oats) and usually hops, fermented using baker’s yeast or harvested yeast. … It takes about 20 kg of malt and 50 g of yeast to make 50 litres of sahti.” (EU)
Depending on mash yield and yeast attenuation, this ratio will provide wort and beer strengths between 1.090 – 1.100 OG and 8 – 10 % ABV respectively. As cereals, in addition to 20 kg of malted barley, our fifty some liters of sahti included 3 kg of raw and 250 g of malted rye. Mashing usually translates as mäskäys; for sahti the process is called imellytys (making something sweet or sugary). Our wort had the OG of 1.093. The yeast will be the Finnish baker’s yeast.
Juniper twigs are added to water before being brought to a boil. The juniper water will then serve as the basis for eight-step infusion mash:
“Sahti is brewed by gradually adding water to the mixture of malt and cereals, starting at a temperature of around 40 °C, which is increased to around 100 °C by the time the last water is added.” (EU)
The traditional mashing program, therefore, starts with a protein rest well suited for less modified malts. Gradually raising the temperature will serve to give time for both alpha and beta amylase so we can expect a rather fermentable wort.
When the mash is ready, in our case after eight hours of hourly checks, it is brought to a boil before filtering.
Juniper twigs are employed for the sparging and filtering phases. Here, straws have been laid on top of juniper.
“Sahti production is a craft and has its own special equipment: the wooden trough at least is characteristic” (EU)
Wort is recycled until it runs clear. Sparge water is near boiling temperature but we’re not worried about tannins as the malt is not roasted or toasted.
A former milk collection vessel, a maitohinkki, receives the sweet liquid.
A small amount of wort is run into a smaller container and cooled. The brewer will take a small amount of yeast and mix it thoroughly with the starter – until bubbles form.
“wort, which is then fermented into sahti using baker’s or harvested yeast. Top fermentation is used. The main fermentation takes around three days at room temperature or cooler, after which the sahti is kept cool for at least one week. The alcohol comes exclusively from the sugar in the malts and other cereals.” (EU)
It’s time to pitch. Sahti will take two to three weeks to complete fermentation at a cellar temperature, perhaps one week when fermenting warmer.
The cask is made of juniper. Every once in a while, the brewer will take a sip or two to know how the current sahti is developing. Cask-conditioned real ale won’t get any more real than this!
Time to Enjoy
The hard work being done, by the brewer and the yeast, it’s time for a taste. It’s malt, to be sure, a bit sweet, maybe even thick if the fermentation isn’t complete or a large amount of rye was used; bananas and cloves not unlike a hefeweizen; a slight carbonation on the tongue; juniper lingers somewhere there as well; with a somewhat sour (lactic acid) and a definitely refreshing finish. A party on the palate. A party unparalleled, too; no wonder they still make it like they always did.
This is an introduction to ancient homebrewed farmhouse ales of northern Europe. Finnish Sahti is the best known of them, but similar beers exist in the Nordic and Baltic countries: koduõlu in Estonia, gotlandsdricke in Sweden, maltøl in Norway and kaimiškas in Lithuania.
Once upon a time there were farmers who brewed beer from their own grains. They malted the grains, picked seasonings from the nearby forest, and fermented the brew with their house yeast. These farmers were not professional brewers, but they passed on their craft, word of mouth, from generation to generation.
Today farmhouse ales are not always brewed exactly this way, and the term refers to the origin of the tradition. For many the designation brings instantly Belgium and France to mind, but it is a much more generic term. Once most beer in Europe was farmhouse ale.
What confuses people is that, unlike Belgian and French farmhouse ales, the Nordic and Baltic traditions are still largely domestic brewing practices, an ancient way of homebrewing. That’s why these traditions are unique within the beer cultures of Europe. That is also why these beers are rarely exported, can be hard to find even in their own countries, do not store well, and unlikely will become commercial hits. Admittedly, there are some commercial farmhouse breweries in the Nordics and Baltics, but basically they have just scaled up the old domestic techniques.
In this text I will concentrate mostly on the ancient ales that have survived to the present day: sahti in Finland, koduõlu in Estonia, gotlandsdricke in Sweden, maltøl in Norway and kaimiškas in Lithuania. These traditions stem from the same origin and have much in common. It is not certain when these traditions took shape, but likely they developed during the Iron Age, before the principles of modern brewing were established in the Middle Ages. See History of Farmhouse Ales for details.
In all Nordic and Baltic countries the word for beer derive from the same origin as ale: olut in Finland, õlu in Estonia, öl in Sweden, øl in Denmark and Norway, alus in Lithuania and Latvia. Hence I like to speak about ales, but I do not intend to refer to the ale-beer or ale-lager classifications.
Nordic refers to the countries of Denmark, Finland, Iceland, Sweden and Norway. Baltic countries are formed by Estonia, Latvia and Lithuania. All these countries are linked by the Baltic sea, and throughout the history there has been immigration and flow of culture between these countries. Northern Germany has been influential to the history of this area as well. Finland and the Baltic states have received Finno-Ugric and Slavic influences from the east. Through the expansion of the Vikings during 750–1050 AD, the Nordic influence is seen for example in the British Isles.
Farmhouse traditions are alive also in Latvia, but Lars Garshol’s travel story Stone brewing in Latvia seems to be about the only information in English. In Denmark the traditions have faded relatively recently, and there are still people remembering the time. Some farmhouse brewing has survived in Russia as well, especially in the Chuvash republic. See also Lars Garshol’s view on Farmhouse ales of Europe.
Daily and Feast Ales
Farmhouse ales have been made in different strengths for different purposes. Low alcohol small beers have been part of the diet and drank by everyone, children included. In the feasts ale was expected to be rich in taste and strong in alcohol. For example, sahti should have at least 6 % ABV. Besides alcohol content, this division has also a distinct effect on ingredients and brewing techniques. Daily ales should be easy to brew on a weekly basis, while the feast ales should be the best the house has to offer.
There are also medium strength ales of 5–6 % ABV which put smile on lips, but do not stop the work. In Finland and Estonia traditional ales seem to be mostly either small beers or feast ales, but medium strength ales exist in Norway, Sweden and Lithuania.
The ales of alive traditions mentioned earlier are either feast or medium strenght ales. The traditions of small beers seem to be largely extinct, but there might be some well-preserved remnants in the Baltic states. Several modernized versions of traditional small beers are still brewed and sold in northern Europe, like kalja (Finland), svagdricka(Scandinavia), gira (Lithuania) and kvass (Russia). Read Small Beer Called Kalja for details on historic low alcohol farmhouse beers.
Malted and unmalted grains, juniper branches, hops, and yeast are the basic ingredients of these ales. Malted barley is the most common base, but also rye, oats, and wheat are used in both malted and unmalted forms.
Unfortunately, traditional home malting has mostly disappeared, and now most brewers use commercial malts. In Norway and Lithuania, some brewers still malt in the traditional way. In Finland, some farmers have revived home malting, but to my knowledge, nobody malts in the most traditional way in smoke saunas or drying barns.
Juniper is the most important brewing herb in the Nordic and Baltic farmhouse ales. Traditionally the juniper flavor comes from the branches laid on the bottom of the lauter tun filter (see image below) or from juniper infusion (branches infused in hot water). The taste of branches is needle-like and woody, somewhat different than the flavor of berries. Hops are used fairly often, but usually in minor quantities. Sahti is often unhopped.
Lithuania is a notable exception to what I just said. Their farmhouse brewers generally do not use juniper, but slightly more hops. Nevertheless, Lithuanian kaimiškas is typically malt-forward, but some versions can be even described as hoppy.
House yeasts are rare these days, but some brewers in Norway and Lithuania are still fermenting with their traditional heirloom yeasts. In the past, some houses made both bread and beer with the same yeast, and hence it is natural that many traditional brewers use now baker’s yeast, though commercial. Some use also brewer’s yeast, but in sahti, only traditional house yeast or commercial baker’s yeast are allowed. This rule is written in the EU Traditional Specialities Guaranteed appellation of sahti.
Other than aforementioned ingredients have also been used, but during the last hundred years, it has been surprisingly rare. The most notable exception is the use of honey (or nowadays sugar) in gotlandsdricke. See Lars Garshol’s take on Nordic brewing herbs.
For those unfamiliar with brewing, I review shortly the essential brewing terms. With very few exceptions, a modern brewery is operated as follows: first malts are mixed with hot water. This procedure is called mashing and the mixture mash. Then, the sweet liquid of malt sugars called wort is drained from the mash in the process of lautering. Finally, the wort is boiled with hops, cooled, fermented and packaged.
Accordingly, a modern brewery has always a big kettle for boiling the wort with hops. In the old times, farmhouse brewers could not afford big kettles, and their methods evolved around wooden brewing gear. The most traditional farmhouse setup involves two large wooden vessels: A tub for mashing, and another tub or a trough-like vessel, known as kuurna in Finland, for lautering.
Wooden vessels cannot be heated externally, and an old trick is to drop hot stones into the concoction. However, with hot stones, long boils would be awkward, and hence the ancient farmhouse brewers skipped the wort boiling step altogether.
This lack of wort boil has a tremendous effect on the beer and is one of the major traits of Nordic-Baltic farmhouse ales. A beer from a non-boiled wort has a short shelf life, but when fresh, has an exquisite taste of malt and cereals. Due to retained proteins, it also feels nutritious, smooth, and full-bodied. An ale completely devoid of boiling steps is called raw ale.
Today many farmhouse brewers use stainless steel equipment, but their brewing process is inherited from ancestors as if the brewers still had only wooden tubs and a thermometer had not been invented. Some present-day brewers boil the mash instead, which is most likely a remnant from times when the mash was heated up to a boil with hot stones. There are also farmhouse brewers who boil their wort, but the boil time can vary wildly from one minute to five hours, again something completely different to modern commercial breweries.
Typically these ales are fermented warm for a day or two and then transferred to a cool cellar. With house yeasts, the traditional fermentation temperature is milk-warm (35–40°C). Often a considerable amount of residual sweetness remains and a slow secondary fermentation keeps yeast active, protecting from staling and souring. These ales are usually served within 1–3 weeks from the brew day.
As you may have noticed from the photos, these farmhouse ales are made in surprisingly big quantities, though still homebrews. See for example the very old looking, but still actively used wooden tubs in the header image. Paavo Pruul, a fine koduõlu brewer from Hiiumaa, Estonia, inherited those tubs from his grandfather. The tubs are designed for producing 100–200 litres (26–53 US gallons) of ale, which is a fairly typical farmhouse batch size.
These ales have survived from the arrival of distilled alcohol, the onset of cheap industrial beer, the temperance movement in the Nordics, and the Soviet reign in the Baltics. Without rich and unique taste these traditions would surely be dead by now. The taste is so different from modern beers that the first-timers may have difficulties to judge if the pint is as it supposed to be. Here is a briefing what to expect.
There are some regional preferences, sort of sub-styles, but the distinction is not always very clear, as the variation from brewer to brewer is often enormous. For this reason, these traditions are not exactly defined beer styles in the modern sense. Besides, even the same ale can taste different every time, particularly due to differences in age and storage. Although these ales may go sour when they age, sahti in particular, sourness is usually considered a flaw.
The appearance is often turbid, but haziness is more related to high protein content, rather than yeastiness. Some yeast are may be suspended, but the obvious sensation of yeastiness is a flaw. Due to proteins, the mouthfeel is typically smooth, and sometimes highly viscous and milkshake-like. In the Nordics, these ales are typically served still or with slight carbonation, while in the Baltics farmhouse ales are more often served clearly carbonated. Color ranges from yellow to dark brown. In the Baltics, paler examples are more typical, but in many parts of the Nordics reddish brown color is sought-after.
Most examples taste sweet with rich fresh maltiness and graininess. The paler ones are more honeyish and grassy, while the darker ales express dark bread and toffee. Many Lithuanian ales have a unique hay-like taste from local malts. Taste of juniper varies from none to pronounced, more inclined to the needle-like taste of branches than berries.
Usually, these ales have expressive fruitiness and spiciness from the fermentation. Quite often sahti has a prominent banana aroma, somewhat similar to weizenbocks. However, some brewers prefer their sahti malt-forward with no signs of banana. Some Lithuanian examples may have notes of butter. The overall impression is extremely fresh, nourishing, smooth and drinkable.
In the past, these ales would have picked some smokiness from the malting process, but today smoke aroma is rare, except in parts of Norway and Gotland where brewers malt themselves.
In 2014–2015 I wrote the book Sahti: Elävä muinaisolut (in Finnish) with Johannes Silvennoinen and Hannu Nikulainen, and the bulk of my research was done during that time. We traveled 8000 km in Finland and Estonian islands, interviewing about 50 sahti and koduõlu brewers, and tasting more than one hundred examples of these ales. I also interviewed experts and scientists on malting, yeast, archaeology, botany and baker’s yeast production. I have been homebrewing sahti since 2004, receiving numerous brewing tips from true farmhouse brewers. For the book, I made several brewing tests on farmhouse ingredients, techniques and recipes.
The foundation for sahti knowledge have been laid by a Finnish ethnographer Matti Räsänen, surveys of Suomen sahtiseura (Finnish Sahti Society), and the thesis of Carl Niclas Hellenius from 1780:
Räsänen, Matti (1975). Vom Halm zum Fass: Die Volkstümlichen alkoholarmen Getreidegetränke in Finnland. Suomen Muinaismuistoyhdistys, Kansatieteellinen Arkisto.
Räsänen, Matti (1977). Ohrasta olutta, rukiista ryypättävää: Mietojen kansanomaisten viljajuomien valmistus Suomessa. Jyväskylän yliopisto, Etnologian laitos.
Asplund, Ulla (editor) (1990). Sahtikirja. Suomen Sahtiseura.
Hellenius, Carl Niclas (1780). Finska allmogens bryggnings-sätt. Doctoral thesis for the Academy of Turku. Digitized by The National Library of Finland.
These have been the most important sources on other related farmhouse ales:
Nordland, Odd (1969). Brewing And Beer Traditions In Norway: The Social Anthropological Background Of The Brewing Industry. The Norwegian Research Council For Science And The Humanities.
Salomonsson, Anders (1979). Gotlandsdricka: Traditionell kultur som regional identitetssymbol. Press’ Förlag AB.
Jakovlev, Tormis (1995). Olut Virossa. Tampereen museot.
Markowski, Phil (2004). Farmhouse Ales: Culture and Craftsmanship in the Belgian Tradition. Brewers Publications.
As a background material, I have used several books on Finnish folk culture, for example by Toivo Vuorela, Uuno Sirelius, Ilmar Talve and Satu Apo. These books are mostly written in Finnish, but one is also available in English:
Talve, Ilmar (1997). Finnish Folk Culture. Finnish Literature Society.
This story was originally published as Introduction to the Nordic and Baltic Farmhouse Ales in August 2016. This story was very long, and I completely restructured and renamed it in January 2017. The section on history was moved to History of Farmhouse Ales. The section on the availability of commercial examples was moved to Where to Find Commercial Nordic and Baltic Farmhouse Ales? I removed the section on shelf life and storage of sahti, which will be its own article later.
At a recent homebrew club meeting, one of the members asked me a brilliant question – when and how should you adjust your mash pH when all grain beer brewing? This is a devilishly complex question as you want to adjust your mash pH quickly if brewing with modern malts.
The Mash pH Conundrum
I and others have written extensively on the importance of controlling your mash pH and maintaining it in the range of 5.2-5.6 during the sugar conversion step. A proper mash pH contributes to better flavor, complete conversion, and improved long-term stability.
You can use additives like lactic acid and phosphoric acid to quickly adjust your mash pH, and I wrote an article recently on the purchase and care of a pH meter. So one might assume you can just use your pH meter to measure the mash pH after dough-in of the grains and then adjust it using lactic acid from the homebrew shop — right?
The problem is that most modern malts are very highly modified, which means they have a lot more enzymes (diastatic power) that is really needed to convert the sugars in your crushed grains into fermentable forms. Time is also working against us since it takes easily 10-15 minutes to dough in and stabilize the mash pH so it can be measured. Modern highly modified pale malts can in many cases convert the sugars within 20-30 minutes.
It could take 10-15 minutes to dough in, and another 5-10 minutes to get the mash sample down to room temperature to take a proper measurement then calculate and add the right amount of lactic acid. Which means it is possible for the majority of your conversion step to be complete before you’ve measured and adjusted your pH!
Managing Mash pH Properly
Fortunately, you can estimate both your predicted mash pH and the predicted acid adjustment needed using the software. Here’s a detailed article on how to do it in BeerSmith. The only problem here is that the pH estimate is exactly that – an estimate!
So the compromise I’ve settled on is to use BeerSmith to estimate my mash pH, then use that estimated value to determine the amount of lactic acid to use. Then what I do is add about 80% of that acid up front before I mash in. This usually gets my mash pH within the acceptable 5.2-5.6 range, and then I will take a measurement with my pH meter after I dough in and make any fine adjustments needed with some additional acid based on that measurement.
The advantage of this technique is that by adding most of the acid up front, I’m assuring that the mash pH starts in the acceptable range. However, by also measuring and making a final pH adjustment I’m assuring that the pH is stable if the mash conversion takes longer but most importantly assuring the correct pH to support the long-term stability of the beer.
This is the best compromise between treating your mash based only on an estimate and treating your mash pH based on an actual pH measurement.
Gallons * Temp Rise (F)
———————————— * 1000 = Watts Required
372 * heat up time (hours)
So, for a homebrew example of 7 gallons of wort at the beginning of your boil, and desiring to reach boil in 15 minutes, and assuming your wort temperature before boil is 150 degrees F after sparge runnoff:
You’ll have to tweak the formula to account for your starting boil size, typical sparge runnoff temp, and desired time to boil. Another limiting factor is going to be your available amperage to hook up the element. Since watts = amps * voltage, a typical 15 amp household breaker running at 110V will at most power a 1650W element.
The other main concern you’ll want to watch out for is watt density of the immersion element. This is the measure of watts per square inch. Sugary water like wort tends to not conduct heat very well, so you want a low watt density to prevent the sugars from scorching. What qualifies as a ‘low enough’ watt density is something I’ve yet to figure out, but I suspect you’ll be fine with anything at 40 or less watts/sq in. Keeping the wort moving (by stirring) will also mitigate this potential problem.