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This is the first in a series of posts each covering an aspect of brewing mixed-fermentation barrel-aged beers where my opinions have changed significantly since I wrote American Sour Beers. Each post will focus on our process, recipe, and results for one of the beers in the Sapwood Cellars Shipping Club. This one covers Barrels of Rings, aka our 40 IBU hazy pale ale (Rings of Light) fermented in barrels with house microbes, then dry hopped with Citra Cryo.



The longer I brew mixed-fermentation beers, the more I appreciate just how important the hopping rate is. Controlling lactic acid production by inhibiting lactobacillus is hops' most well-appreciated function in sour beers. Hop compounds become more effective at inhibiting Lactobacillus as the pH drops, creating a natural "limit" on their lactic acid production. What it took me a long time to appreciate was how much hop compounds (beyond IBUs) lead to a greater expression of what I think of as classic Brett "funk."

When Scott and I began the mixed-fermentation program in 2018-2019, generally our issue was beers not souring enough. I started pulling levers (lower hopping rates, higher mash temps, less attenuative primary strains etc.) By 2020-2021, we were having excessive acid production... Most non-fruited beers were dropping to a firmly-acidic 3.1-3.3 pH, while fruited beers were often difficult to drink in quantity at 3.0-3.1 pH with some dipping to "obnoxiously acidic" high-2s. 

Fruit contributes simple sugars, which Lactobacillus love, and at the same time dilute the hop compounds in the beer. This can cause a precipitous pH drop. With so much beer already in barrels, my first maneuver was to begin dosing alpha acids into the beer along with fruit when there was already enough acid. We started with reduced iso-alpha-acids (e.g. tetralone/hexalone), but have moved onto Hopsteiner Alpha Extract 20% since it doesn't add perceived bitterness. About .1-.2 g per gallon stops acid production for our bacteria. These products don't significantly change the flavor or add additional aromatic complexity. As a side benefit, they enhance head retention. A small dry hop at this stage would be another option if you wanted stop acidification and add hop aromatics.

 


At this point we started upping the aged hop rate, or aiming for higher IBU targets when using fresh hops (~15-20 IBUs). At the same time (~2021) Scott and Ken (our head brewer) wanted to try barrel-aging more aromatically hoppy beers... I was resistant. I love hoppy-sour beers, I did a whole talk about them at the 2016 National Homebrewers Conference. Generally my approach had been to make sure the hops go into the beer as close to serving as possible (e.g., dry hop a barrel-aged sour after aging, brew a quick-turn hoppy Brett saison, add a whirlpool addition after kettle souring). I'd tasted too many barrel-soured IPAs and pale ales from great breweries that smelled like "old hoppy beer." That said, Ken and Scott convinced me! At our scale it is a relatively low risk to divert a few barrels of pale ale to see what happens.



We're already "aggressive" with our measures against oxygen pick-up (purging barrels with carbon dioxide before filling, purging the barrel-tool between each fill, purging the bottles before filling etc.), but when we fill barrels with pale ale wort we pull out all the tricks. Most importantly, we selected barrels that could be refilled without rinsing, leaving several gallons of "house culture" at the bottom of each. Our goal was to start the secondary fermentation as quickly as possible to protect the delicate hop compounds. I was amazed how good the resulting beer tasted!

What has really intrigued me is that the hoppier bases have almost universally produced finished beers I'd describe as more Brett-forward (earthy, funky, fruity, horse blanket). What I don't know is why! In American Sour Beers I cited research that Brett can free glycosides in hops, so that could explain the fruity. Maybe hops are just inhibiting Lactobacillus, giving the Brett a healthier environment (in lambics Brett tends to thrive before Pediococcus dramatically lowers the pH). Maybe I'm just being fooled and higher hopping rates (aged or fresh) are adding key compounds that I associate with the "funk" in a Cantillon, Orval (and many of my favorite American mixed-ferms)! These days our typical hopping rate is .5 lbs/bbl of aged hops at the start of the boil, and .5 lbs/bbl or fresh low alpha-acid hops in the whirlpool. 



Barrels of Rings is one of the bottles included with the first shipment of the Sapwood Cellars Shipping Club. It started as Rings of Lightbrewed summer 2022, racked into barrels after primary fermentation, but before dry hopping. After 10 months of aging, we transfer directly from the two wine barrels into our blending tank (purged with 5.5 pounds of our selected Citra Cryo already in there). We agitated/roused and allowed to settle for a couple days, dropping the hops. Then we primed with sugar and rehydrated wine yeast (as we do for most of our barrel-aged sours) and partially carbonated the beer. As with the barrel fill, we're relying on CO2 purging of the bottles and the rapid refermentation to scavenge oxygen and preserve hop aromatics. 



Recipe: Barrels of Rings

OG: 1.063

65% Briess Brewer's 2-row

14% Great Western Malted White Wheat

13% Grain Millers Flaked Oats

8% Best Chit Malt

IBUs: 40

.5 lbs/bbl Meridian @ Whirlpool (212F)

1 lb/bbl New York Cascade @ Whirlpool (180F)

Bravo Salvo Hop Extract @ Whirlpool (180F)

Fermentation with Omega Cosmic Punch (the barrel sheet below is incorrect)

FG (Primary) 1.022

Brewed 8/5/22. Barrels filled 8/11/22 

Barrel #6: Fifth-fill Chambourcin red wine barrel that previously held our original barrel-aged pale ale, Measure Twice. That barrel was started with dregs from our collab with Free Will (Erma Extra), but along the way it was filled with bases that had dregs in primary from various American saisons (Casey and Holy Mountain).

Barrel #125: Second-fill Chardonnay white wine barrel that previously held a cider fermented with the Bootleg Biology Biology Mad Fermentationist Saison (plus we added the dregs from a stellar bottle of Barrique Wet Hop Reserve after filling).

6/21/23 116 gallons of beer from the two barrels transferred onto 5.5 pounds of 2022 Citra Cryo. 1.5 oz/gallon.

Carbonated to 2.05 vol, reyeasted with Premier Cuvee (rehydrated on a stir-plate with StartUp Nutrient), primed with enough glucose to add 1.1 vol of CO2 (~3.1 vol total in bottle). 

Final pH: 3.65

Final Gravity 1.009

7.1% ABV. 



Tasting Notes: Barrels of Rings

(My personal notes from a few months ago)

Smell - Nice blend of citrus (orange) and earthy-Bretty-funk. Still really fresh, no oxidative or old-hop aromatics. Really varied nose with a little pine sap, hay, and melon. Another hoppy base that got funkier than most of our bases. 

Appearance - Big dense white head, good retention. Light haze, very pale yellow.  Attractive. 

Taste - Light lemony tartness, but not sour-sour. Very saison-y. Some bitterness, but it doesn’t clash with the light bitterness. 

Mouthfeel - A touch of astringency. Great sptrizy carbonation. Medium-light body. 

Drinkability - Really nice. The bitterness does give it a different impression than a classic low-bitterness sour base. More saison-like. 

Changes for Next Time - Really good, not much to change on this one. Gin barrels would be fun. 



When visiting Epochal Barrel Fermented Ales in Scotland last year I was blown-away by how by how good (owner/brewer) Gareth Young's wild ales were aged on whole hops in the barrels for the entire secondary fermentation. I really enjoyed the first beer we did with it, Violet You're Turning Violet (Mosaic in the barrel, finished with a blend of wild and cultivated blueberries). It seems like a good option especially if you want variety in the hop intensity of a base, e.g., start with a more moderate hopped base and add hops to some barrels for blending options. 


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My book, American Sour Beers, is turning ten next month! I wrote it from the perspective (and experience) of a homebrewer. I wanted to experiment and learn. I really didn't know much about brewing commercially, creating consistent blends, adapting recipes as a barrel program matured, developing flavors that would sell etc. Looking back I have to ask, did my book help launch 1,000 barrel programs, without providing the knowledge brewers actually needed to succeed?


Over the last decade American craft brewing had an explosion of breweries ramping up barrel-aged sour production, followed by a pretty rapid decline (including multiple mid-sized breweries closing their programs and sour-focused breweries closing). Part of that is the inherently less-predictable nature of mixed-fermentation (when you order a cherry sour beer, what are you expecting? Kriek, cherry juice, cherry vinegar etc.). Compare that to a bourbon-barrel vanilla-bean stout where you have a pretty good idea of what the intent was. I suspect at least part of it was the oversaturation of the market combined with the high prices.

Despite brewing my first sour beer in 2006, becoming a brewery consultant in 2011, writing a book in 2014, and opening a brewery in 2018... I haven't been consistently happy with the barrel-aged mixed-fermentations I made until the last couple years. I certainly never released a beer that I thought was bad, but there were certainly had batches that were too sour, muddled, under/over carbonated, or just didn't "pop." During that time we've also released some amazing beers that I still love!

At Sapwood Cellars we've relied on our local club members, and the people who walk in the door to buy ~10,000 bottles of barrel-aged sour beer a year. That may sound like a lot, but it's less than 5% of our production (and we're a pretty small brewery). There really hasn't been much interest in barrel-aged sour bottles in our limited distribution range. They tend to be beers that sell best when you can explain them directly to the drinker, rather than just have them sitting on a shelf! If only there was a way I could talk directly to beer drinkers interested in sour beer...


Rather than bury the lead more than I already have, Sapwood Cellars barrel-aged mixed-fermentation sours are now available for shipping within much of America through a Membership Club administered by Tavour! Shipping is available to: WA, CA, OR, NM, NV, CO, MN, NY, DC, CT, NE, MA, FL, PA, NH, NJ, ID, TX, KS, IN, WI, MO, IA, IL, MI, ND, VA, RI, NC, SC, and MD.

The first installment of the club is $146 (including shipping) for one 500 mL bottle each of six beers: 

Growth Rings 2023: Three-year-blend of barrel-aged Sours, essentially our cuvee of bases, barrels, and microbes showing off our house character. This one isn't refermented with wine yeast, so the dregs would be a good option if you are looking for microbes! It was the second highest-rated "Gueuze" on Untappd in 2023!


Barrels of Rings: Our pale ale base, mixed-fermented in wine barrels and then dry hopped right before bottling. Citrusy-funky with restrained acidity.


Jammiest Bit: Our homage to Hommage, a barrel-aged sour on loads of sour pie cherries and red raspberries. Fruity, funky, tart etc.


Botanicia: A blend of pale sours aged in gin barrels that we then infused with dried limes and quinine. A weird play on a gin-and-tonic... but with a lot more acidity and funk!


Elliptical Orbit 2023: A continuation of the "Dark Funky Saison" series still with my original collaborator and homebrew buddy Alex. For this one he roasted Geisha coffee beans and we infused the barrel-aged dark sour with Geisha cascara (dried coffee cherries). 


Fruit of Many Uses: We sequentially racked the same barrel-aged tart/funky base onto second-use Chardonnay wine grapes, cherries, raspberries, and white nectarines. All of the fruit was whole/local.


Over the next couple weeks I'll be posting my detailed tasting notes on each of the beers, along with recipes, lessons learned, and suggestions for brewing something similar at home! I'll repeat for each club release, assuming enough people sign-up for the club to make it viable. 

Over the last five years it isn't "one simple trick" we learned that improved our beer. It's the accumulation of 100 little things from ingredient selection, to blending, to process refinement, to equipment that we've figured out. It's sitting down with each beer, drinking, thinking, taking detailed notes, and iterating. So much of it is not doing it by myself, having Scott, Ken, and Spencer to push to do things I wouldn't have (Botanica was Ken's baby, and Barrels of Rings was Scott's). Both are delicious, and they are certainly beers I would not have brewed if it was all up to me!




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Thiols are the coolest thing in brewing hoppy beers since the invention of dry hopping. It seems like almost every collab Sapwood Cellars has been invited to brew over the last 18 months ends up "Thiolized": 3S4MP (Cosmic Punch IPA with Phantasm and Nelson Sauvin at Fidens), Cone Concentrate (Cosmic Punch DIPA with Simcoe at Other Half DC), Celestial Paradox (London Tropics IPA with Strata/Galaxy/Citra/Simcoe at Toppling Goliath), Yasokeee (Helio Gazer DIPA with Peacherine, Hydra, and Phantasm at Cushwa), and most recently Heisenberg (Helio Gazer DIPA with Galaxy/Nelson at Commonwealth).

So why all of the excitement from our fellow craft brewers? Obviously many of the collab requests are due to Scott's writing about and advocacy for thiols, but are they just something new that will be passé soon, or are these strains here to stay?


What Are Thiols?

Thiols are sulfur-containing compounds that are often potent aromatics. The ones brewers are excited about are tropical, winey, and citrusy, while other thiols are intensely unpleasant with aromas of garlic or rotten eggs... which is why the thiol mercaptan is added to natural gas to alert people to leaks. The "skunky" aroma of light-struck beer is also 3-methyl-2-butene-1-thiol.


Unlike many other beer aromatics that require concentrations in the ppm (parts per million) or ppb (parts per billion) many thiols have an aroma threshold in the range of 5-70 ppt (parts per trillion). This means that it doesn't take much of them to be apparent, but also means that it doesn't require "high" concentrations to become dominant. 


In terms of positive beer and wine aromatics, the thiols that get the most attention are 4MMP, 3MH, 3MHA, and 3S4MP. These have perceptions that range from passionfruit, to grapefruit, to rhubarb. These are the intense aromatics that give New Zealand Sauvignon Blanc wines their distinct aromas and are found free at low-levels in many New Zealand hops (as well as some other varieties from around the world).


Most of the thiols found in hops, malt, and other botanicals are bound and thus not active aromatically. Enzymes are required to free them. There are wine strains available capable of this, but getting those genes into brewer's yeast requires more work. 



Where Do Thiols Come From?

Bound thiols are found in both malt and hops, but levels vary widely. The bond in need of breaking comes in two "flavors" Cysteinylated (Cys) and Glutathionylated (Glu). The vast majority (90%+) in both malt and hops is Glu. The IRC7 gene in certain wine strains and Omega's Cosmic Punch can only work on the less common Cys. As a result, mash hops are most potentially beneficial for Cosmic Punch, as the enzymes in the mash (especially in the acid-protein rest temperature range) can help convert Glu to Cys. Luckily some less expensive hop varieties have the highest levels of bound thiols. We've used Saaz, Cascade, and Calypso with good results.


The more intense strains like Berkeley Yeast Tropics line and Omega's Helio Gazer, Star Party, and Lunar Crush can simply be added to a standard recipe with or without whirlpool hops. Rather than having more copies of the IRC7 gene, they have a wholly different gene which can free Glu-thiols directly. The IRC7 gene in Cosmic Punch is "sourced" from yeast, while patB Omega uses in the more assertive strains is from a bacteria (if transgenic CRISPR/Cas9 gene modification is a step too far for you). We fermented a kettle sour which only had a small dose of hexalone (isomerized hop extract for head retention) with London Tropics. The result was intensely passion-fruity, so much so that it could almost pass a fruit beer. 


GM (genetically modified) yeast strains aren't allowed in commercial beers in many countries (e.g., Canada, New Zealand). As a result there are labs working with wild isolates capable of freeing thiols for co-fermentations (e.g., CHR Hansen - it is primarily marketed for NA beers) and breeding strains with heightened thiol freeing capabilities (e.g., Escarpment). Omega initially worked on yeast breeding between English ale and a wine strain capable of freeing thiols... our trials with it (Designer Baby) were interesting, but had too much of the wine strain's idiosyncrasies present (poor flocculation especially). 



Pros & Cons of Thiol-Expressing Yeast

Pros:
-Intense aromatics that are otherwise impossible to achieve from hops, malt, and yeast
-Thiols have incredibly low aroma thresholds... measured in ppt (parts per trillion)
-Thiols are "free" no expensive hops or fruit required
-Thiols may help increase shelf-life by scavenging oxygen

Cons:
-Higher perceived "sulfur" aromatics are frequent in thiol-freeing strains
-Some brewers/consumers/countries prefer to avoid GM ingredients
-Thiols can be "one note"... is it really that different from adding a jar of passion fruit extract?
-Repitching the yeast doesn't make as much sense if you also want to brew English Ales, Porters/Stouts etc. 



More isn't (always) Better

Initially there was a focus on maximizing thiol concentration. This could include colder fermentation temperatures, mash hops, and engineering strains with more assertive genes. Like most aspects of brewing (or cooking) maximizing a single flavor compound doesn't usually result in the best overall flavor or balance. 


Thiols aren't typically a "primary" aromatic in beer, so a beer with over-the-top thiol concentration without anything to play off of can taste artificial. On the other hand, some of our heavily dry hopped DIPAs have tested at over 100X the flavor threshold for 3MH and still weren't the primary aroma thanks to competition from the "traditional" hop aromatics. From those test, I wouldn't worry about dry hopping removing all of the thiols.


As a general rule, I'd suggest using a more restrained approach to thiols in lighter/cleaner/simpler beers. It doesn't take much to add a unique twist to a lager or American wheat, where a double-dry-hopped DIPA or fruit beer may benefit from a much higher amount. In the end it's about your palate and goals for a beer. 


In my experience expressing thiols doesn't make every hoppy beer better. They add a distinct note that can greatly enhance the perception of passionfruit-type aromatics. That is a wonderful contribution when you are leaning into those flavors, but can be distracting or muddle other flavors. For example, I love the "mango popsicle" aroma of great Simcoe. However, with one of the intense strains like London Tropics or Helio Gazer in an all-Simcoe beer can become more generically "tropical" rather than varietal "mango." On the other hand, when dry hopping with passion-fruity Galaxy, or brewing with actual passionfruit the thiol note helps to enhance the existing aromatics. 



Phantasm

Hand-in-hand with thiol-expressing yeast goes Phantasm. It is essentially the dried and powdered remnants of the highest-thiol New Zealand Sauvignon Blanc grapes. As a result it comes with a high price-tag of ~$35/lb. It really doesn't smell like much before fermentation. Added to the whirlpool it adds a huge amount of bound thiols for the yeast to work on. 


During fermentation I detect a distinct "white grape" flavor and aroma that I don't get from other thiol-expressing ferments that rely on grain and hops alone for bound precursors. A lot of this drops out with the yeast however and the finished beers are rarely as distinct. To my palate the added expense is hard to justify in a highly-dry-hopped beer where the thiols are competing against other big aromatics. Unless you lean into those aromatics with a hop like Nelson Sauvin. I like Phantasm best when it is paired with actual white wine grapes, or in a simple base where it can star. 


We haven't used Berkely Yeast's "Thiol Boost" additive yet... but I'm just not that excited about a 15X increase on the already intense London Tropics level of 3MH. I'd be interested in herbs or additives that could push other unique thiol aromatics that we aren't getting from grain/hops. 



My Favorite Thiolized Batches

At Sapwood Cellars, we've brewed a few dozen batches between Cosmic Punch, London Tropics, Lunar Crush, and experimental isolates. I've enjoyed most of them, but a handful stand-out as beers I loved!


Cosmic Rings: Galaxy and Citra is one of our favorite combinations... but we have had a difficult time sourcing great Galaxy (that doesn't taste like honey roasted peanuts). This all-Citra double-dry-hopped pale ale starts with New Zealand Taiheke (Cascade) in the mash and kettle. It's one of our favorite whirlpool hops because it is low alpha acid and has a beautiful tropical aroma... not to mention a lower price compared to other New Zealand varieties like Nelson Sauvin and Riwaka. Then we ferment with Omega's Cosmic Punch which brings some tropical aromatics without becoming distracting or artificial. Finally we dry hop with Citra and Citra Cryo at a combined 3 lbs/bbl.


Tropical Pop: Kettle sour fermented with Berkeley Yeast London Tropics along with passion fruit and mango purees. Passion fruit is expensive, fermenting with London Tropics boosted the passion fruit aroma allowing us to use less without sacrificing the aroma intensity.


Field Learning: As a homebrewer I loved being able to dump a bottle of thiol-rich New Zealand Sauvignon Blanc into a keg of mixed-ferm saison. That wouldn't be legal commercially, but what we did for this collab with Bissell Brothers was to brew a restrained base with Hallertau Blanc in the mash and Phantasm in the whirlpool and age it in fresh Sauvignon Blanc barrels along with Bissell's house culture. After a year we added fresh Chardonnay grapes from Crow Vineyards here in Maryland. The tropical notes from the thiols survived barrel aging and gave the beer depth we wouldn't have gotten from grapes and barrel alone.



Takeaways

Are thiols a scam? No, but they also aren't an innovation that fundamentally changes what it takes to make a delicious beer. Consider a thiol-freeing yeast when additional passionfruit-type aromatics will enhance your beer. Don't worry about maximizing the thiols unless you they will be competing against other strong aromatics. 


I suspect that this is just the lead in to even more exotic genetically modified yeast strains (we have a pitch of Berkeley's Sunburst Chico which is modified to express high levels of pineapple-y ethyl butyrate). If you can produce a flavor compound without the cost, environmental impact, variability of growing it I suspect the economic pressures will be too great! That said, making delicious beers isn't about maximizing one or two compounds (in the same way that vanilla flavoring is inexpensive, but doesn't fully replace the depth and complexity of real vanilla beans). 




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