Juniper-Spicebush Sour

 I’ve been reading a bit about brewing lately - whole, paper, non-fiction books, which is a bit of a divergence from my usual Sci-Fi-Audiobooks-Only diet - and the two that we’re the most excited about are American Sour Beers by Michael Tonsmeire and The Homebrewer’s Almanac by Aaron Kleidon, Marika Josephson, and Ryan Tockstein, the owners of Scratch Brewing. This latest brewing effort is sort of a first effort in both directions. 

Luke managed to find a relatively large quantity of spicebush on a hike earlier in the day, a native plant that is edible root to berry and that was allegedly the seasoning of choice for prairie dogs and possums in pre-colonial America. When its berries are red and mature, they are supposed to be fabulously peppery, almost like allspice, but they are also edible green and, from our taste tests, citrusy, peppery, and zesty. 

I’ve been baking sourdough bread for years with my now almost ten-year-old starter John Dough, and Luke has been working sourdough into his pizza doughs to very satisfying results in his professional life as the pizza chef at Brightwood Bottle & Pizza. We’ve done a few brews with sourdough starter as the yeast to interesting results, but we’ve never done a proper sour beer and I was really excited to learn that Scratch Brewing uses sourdough starter in some of their brews to first acidify the wort with the lactobacillus present in the starter and then let the yeast take over to produce alcohol. 

We used a very similar base recipe to our recent Juniper Kveik Ale (tasting notes for that are going to be forthcoming) with the addition of a loaf of sourdough bread that I baked a few days before, cut into cubes and dried. I’ve never gotten an absolutely clear answer on what kind of character and sugars bread adds to wort, but I like the idea. 

One of these days we’re going to get around to experimenting seriously with Kvass (a beer-like beverage from Eastern Europe that uses bread as the main source of fermentable sugars) and Kvass hybrids, but my guess is that it adds a whole range of interesting sugars. We make bread with unmalted wheat of course, which generally provides sugars that Saccharomyces can’t easily break down, but then the wheat is fermented in the dough, then baked, which could do any number of things. Maybe the baking breaks down some sugars into forms that are more easily fermentable, maybe it caramelizes some of the sugars, maybe both!

We also added a bit of extra acidulated malt to bring the starting pH down to 5.15. That isn’t particularly low, but it’s a bit below normal and a bit under the ideal range for the enzymes in malt to convert complex sugars into simpler sugars. Our thinking here is that this should help to give the lactobacillus a bit of an edge early on, since it likes a slightly more acidic environment, and provide it with extra sugars that the Saccharomyces can’t get at.

We used the same juniper extract as last time to bitter the wort without (hopefully) affecting lactobacillus activity and added in about a tablespoon of spicebush berries halfway through the boil. We didn’t find that the juniper provided much bittering to the ale last time, but that may be just about right for a sour. Apparently juniper can be a bit unpredictable in how strong its character comes through, but I hope it’s at least noticeable in the finished beer. We also went a little light on the spicebush berries in the interest of caution. I suspect that this will end up as a slightly malty, pale sour with a hint of character from these additions and that we’ll be looking around for a good companion fruit to age this on in secondary, but we’ll see.

We’re going with a quick souring method here, not too different from kettle souring but without the second boil. Instead, we just cooled the wort down to just above 100F, moved it into a carboy, pitched the starter, and wrapped a coat around it to keep it from falling to room temperature too quickly. Ideally, the lactobacillus should thrive early on thanks to the warm temperatures, light pre-acidification, and salt addition. Once it hits its acid tolerance - between pH 3.1 and 3.5 - and the temperature comes down, the Saccharomyces in the starter should take over and bring us home. We’ll keep an eye on it and pitch in some brewer's yeast if these early conditions prove to be a little too much for it to hang on.

In The Homebrewer’s Almanac, Scratch Brewing recommends cooling to 100F and simply letting the temperature in the fermenting wort rise naturally. (In fact, in an email, Marika Josephson mentioned that they now bring it all the way down to 80F to keep the sourness from getting too sharp.) We considered leaving the insulating coat off, but decided to keep it with the thought in mind that an uninsulated commercial sized batch would likely hold its temperature for a lot longer than our little six gallon batch. We’ll keep it insulated for a few days, check out its pH, and decide what to do from there.

We have no idea how the yeast in the sourdough starter is going to act at these temperatures - hopefully it doesn’t produce too many off flavors early on - and we’re not sure what kind of character our foraged and baked ingredients are going to add here. We may end up tasting this one in a week or so and deciding on a wildly different course for this beer. If it has a lot of weird esters from the stressed yeast, maybe some Brett might help us out by chewing through them? There are a lot of unusual variables at play here, but I’m excited to see how this one turns out! 

Stats:

Volume in Fermentor: 6 Gallons (+ half a gallon saved for other projects)

Starting Gravity: 1.04

Water:

• 6 Gallons Infusion Mash
• 4 Gallons Batch Sparge

Fermentables:

• 9 lbs Pilsen Malt
• 2.2 lbs White Wheat Malt
• 4 lbs Malted Oats
• 1 lb Flaked Oats
• 1.1 lb Sourdough Bread, cubed and dried
• 14 oz Acidulated Malt*

Bittering/Flavoring Additions:

• 1,100ml of juniper tea made with 150g of juniper branches, boiled for 1 hour and added to the hot liquor tank before mash
• 1 tbsp of green spicebush berries, foraged the same day and crushed, @ 30 minutes

Other:

• 0.9g Gypsum**
• 2.8g Calcium Chloride**
• 1.9g Epsom Salt**
• 1 tsp Yeast Nutrient
• 1 oz Kosher Salt

Microbes:

• ~ 300g active sourdough starter, fed 24 hours prior

Schedule:

• Mash for 1 hour at 150F
• Batch Sparge for 20 minutes at 160F
• Boil for 1 hour
• Cooled to 105F, pitched the sourdough starter, and wrapped in a coat to hold temperature for ~48 hours
• Ferment for a further 7-8 days at 68F
• Decide from there whether we want to do a secondary fermentation on fruit

Notes:

* We intentionally acidified to pH 5.15 to give the lactobacillus a head start and to add more sugars that Saccaromyces can’t ferment (again, for the lactobacillus)