Kuurna Prep

I started with sanitizing my filter by putting straw and blackberry canes in the oven at 225F for 2 ish hours, the length of the brew. I also soaked the kuurna in the bathtub with 5 juniper berries in a tea strainer for this time. Traditionally, juniper branches are used for filtering and cleaning due to antimicrobial properties, but I don’t yet have access to eurasian juniper. Raspberry canes are mentioned as an alternative on p 136 of Viking Age Brew.

Brew

This vaguely follows the method on p 203 of Viking Age Brew.

I started with 16qt of water hot from the shower at ~100F. I start the stove on med heat to start, went up to med high when I added the grain bag. Once I had all the grains in, the water level looked low, so I add 1.5L 175F water twice, using my electric tea kettle to heat it. Once the kettle started making the bubbling sound, and the thermometer read 140F at least part of the time, I start a 45 min timer - turn down the stove to 3 dots.

After the first timer ends, I restart the 45 min timer, and bump the heat up to med high/med. I turn it down to 4 dots when the thermometer reads over 158F. At this point, I start the electric tea kettle at 195 to get more  water to 190F for sparging (filtering thru the malt).

After the 45 mins finishes, reset the timer for 15 min, and turn up to med high. When bubbling, I turn down to med or 4 dots. Goal temp here is 176F. (Go set up the kuurna.)

I ladle a bit out to taste.

Turn off the stove!

Lautering (Filtering)

Now I set up the kuurna with straw and blackberry canes. I also put cheesecloth over the hole to keep more grain out, but I think this was excessive and I won’t do it next time. 

This is the first time I’ve used juniper berries to approximate the flavor of the juniper, so I added a handful of berries to the filter. 

I needed to balance the grain bag on a cookie sheet to dump the malt into the kuurna. (If I don’t use black berry canes next time, I can put the bag straight in the kuurna without snagging on thorns.) I was planning to cycle the wort thru the grains a second time, but the balance of the bucket and the slowness of the drain made me decide to try that a different time. When I had 2 gallons, I switched to the bigger bucket. In all, I ended up adding the 1.8L kettle 3 times at 195F to the sparge, as well as 2 soup kettles heated to hot to touch and steaming, and the 1.8L kettle one more time at 185F to get approximately 5 gallons total? The big bucket is a little over half full.

Fermenting

As the buckets cool, I started water to boil for the yeast. This time I used regular Red Star Bread yeast. Once the water has cooled, I put the yeast in the water. I also added 2 unsanitized blackberry branches to the bucket I’m going sour, because that was the first way I ended up with an accidental sour.

(You might notice that I put the buckets in a low cardboard box. After an incident with ants in cider a few years back, we always put our fermenters in a bucket that has a dusting of diatomaceous earth at the bottom to stop ants.)

Typically, cooling takes pretty much all day - last time I went to D&D for 8 hours and it was barely cool enough to add yeast when I got back. And I don’t even have to wait for room temp, because bread yeast goes warmer than beer yeast. This time, the buckets were at about 110/100F before we left for D&D, about 3 hours. I think that running thru kuurna helped, also that I put the kuurna outside and it was cooler than inside. I added the yeast to the small bucket and a gloop of sourdough starter to the sour bucket (hey, it worked last time) and took the original gravity.

Then, I wrapped both buckets in my heated blanket. The yeast was blooping by evening, and the sourdough one was blooping by morning. Because I had a longer amount of time before the event, I let the yeast run longer than I usually do, 3 days instead of 24-36 hours. Then I have to decide if I’m going to rig a cold spot for the 3 gallon carboy or if the weather is going to be cool enough to fake it. 

Second stage ferment/Finishing

Just under 2 complete days later (45 ish hours), I decided the yeast was done with most of its blooping. I transferred the smaller, non-sour batch to growlers and put it in the fridge. It will still probably need burping over the next 2 weeks. The sour batch went into the 3 gallon carboy, but I had an extra half gallon, so there are two carboys. I’m leaving these at room temp to help with the souring process (and I don’t have a cold space big enough). 

Sahti is typically cold-conditioned (cellar temperature) for about a week, but in the summer, I find the fridge to be close enough. 

In just over 10 days, I will have to make sure I have 3.5 more gallons of growlers to transfer the sour to.

(6/18) 

Bottling

I retransferred the sahti to different containers to leave the silt behind as much as possible. The first-run stayed pretty steady in its gravity for an ABV of 8.27% and a light carbonation. The second-run sour fermented a little more for an ABV of 3.15%. I have 1 gallon plus a 32 oz jar of the first-run, and 2 gallons of the second-run sour in the fridge to transport to AnTir West War. I decided to leave the siltiest gallon and a half of the sour to go a little longer and see what effect a longer souring process has on the taste. 

(I saved a jar of the yeast from the first-run to use for fermentation agent in the future, and a jar of silt from the sour to see if it works as a souring agent.)

6/30/2024

A couple weeks after war (7/21), we bottled the remaining sour - it's still pretty tasty!

Sources and inspirations

Laitinen, Mika. Viking Age Brew: The Craft of Brewing Sahti Farmhouse Ale. Chicago Review Press, 2019.

Ulf the Wanderer made the kuurna for me.

Otto Gottlieb provided the juniper berries, in addition to context and discussion over the use and availability of juniper. 

Phillip de Greylonde for geeking about wild yeast and sours.

Baron Piaras and Baroness Melisandia encouraged me to keep experimenting with the sour version.

Istvan introduced me to hot scotchies ;)

Colby helped with spilled grain clean up.

Arnora helped me hold the kuurna while I got the bucket set up, and continues to provide inspiration for my SCA in general.