Bière de Coupage: Aged Sours

For this next post in the series on bière de coupage, I'm going to try to summarize my experience to date of making such beers with aged sours, and talk about some recent batches made with this process.

For a while I thought that coupage was something brewers did after primary fermentation.  That's certainly true of most contemporary versions, but Dave Janssen directed me towards some material that suggests that  this wasn't the only process used by earlier brewers.  Some of the details are still unclear, but at least some of the material that Dave has passed on to me suggests that in some cases a small portion of aged beer was added at the beginning of fermentation, rather than after primary fermentation was complete.  This practice is often mentioned in connection with seasonal brewing, and its a running theme that coupage is a necessity if brewing in the summer.  This fits with the idea that the aged beer was used to steer fermentation in the right direction, by inoculating with bacteria and yeast that had proven themselves to make a positive flavour contribution, and also perhaps by lowering the pH of the wort to a point that would inhibit spoilage organisms in the early stages of fermentation.  (I do not mean to suggest that the brewers understood it in exactly these terms.)  This process is closer to using aged beer to inoculate a solera than it is to using it to contribute particular flavours to a blend.

The way I typically use aged sours is somewhere between these two practices.  My primary purpose is to modify the flavour of the young beer, adding some aromatic complexity and a degree of tartness.  But I also want the blend to slowly evolve over time, as the bacteria and yeast from the aged sour gradually take over the flavour profile.  For me, noticing how a batch gradually changes is one of the pleasures of home brewing, and I've started to think a lot about how to brew beers that will go through a positive evolution as they get older.  I'll say a bit more about that below.

When it comes to choosing base beers for this kind of blending, I generally follow this advice from Garrett Crowell at Jester King: "Beyond both components of the blend being dry/done with fermentation, there aren't any special requirements for making biere de coupage [except perhaps] a nice level of acidity in the aged beer".  Although this can be hard to predict, I think the most important thing is to have some picture of where you want the final blend to end up.  I like this general advice from Ron Jeffries, found in Brew Like a Monk, even if its a little harder to apply to blended beers:

Key in writing a great recipe [or making a great blend!] is to begin with the end.  You must begin with the finished beer.  You need a very clear vision of the beer you wish to brew.  How does it look, what color is it?  Does it glow; does it sparkle, or throw a yeasty haze?  How does the head look, its color, texture, and lacing.  Breathe in deeply through your nose.  How does it smell?  What does the aroma tell you about the beer?  [Etc.]

Sometimes I want to accentuate and the fruitier flavours of a base beer with some tartness, and compliment them with some of the sharper citrus, hay, and overripe fruit you can find in aged sours, so I look for beer that I think will pair well to this effect.  Other time I want to add a soft layer of barnyard funk and a lighter tartness to complement a more phenolic or earthy-hop-driven saison, so I'll use a blending component that I know has some of these aromas and flavours. Over time I've found myself preferring base saisons with a fairly clean fermentation profile, since I now want any brettanomyces-related funk to emerge slowly after blending.  I also don't mind a bit of bitterness, even when blending with a tart beer, since what I want is for the balance between this bitterness and the tartness of the sour to gradually shift as the beer ages.  My guide here is Yvan de Baets' description of Rodenbach-era XX Bitter: "When young, the bitterness predominated, balanced by a light tartness.  As it aged, the bitterness diminished, giving way to a more pronounced and lightly vinous tartness."

Using dry/fully-fermented beers is certainly the easiest way to make these blends, and I take the usual steps to ensure that the base beer finishes as low as possible (step mash, plenty of oxygen, healthy yeast).  My saisons can end up anywhere between 1.006 and 1.000, depending on the blend of yeast I'm using, and the aged sours are typically in a similar range.  If I want to blend straight-away without worrying about over-carbonation I try to get the saison as dry as possible.  One way to do that is to use a highly attenuative strain like Wyeast 3711, which can take a beer down to 1.000 or lower.  I'm not a big fan of the flavours from that yeast, but one technique I've used with some success is pitching a small proportion of an attenuative strain along with my primary yeast.  A dried yeast like Danstar's Belle Saison is a good candidate here, because you can weigh out a tiny pitch and seal up the packet with a vacuum-sealer.  Another option, if you're planning to let the beers age a bit before blending, is to pitch some brettanomyces along with the saison yeast.  I still do this if I know the beers are going to sit for a while, but in general I want the base beer to have a relatively clean flavour profile at blending, so that the brettanomyces can gradually make its presence felt as the beer ages, rather than dominating from the start.

Most of the bières de coupage I've made at home have used a pale sour from one of my various soleras for the sour component of the beer.  Whenever I take a draw from a solera, I put some of it in gallon and half-gallon glass jugs to save it for this kind of blending.  In the past this has meant that I've varied the final proportions of a blend based more on convenience than tasting considerations.  If I'm planning to blend in a five gallon carboy, I'll make four gallons of saison and blend it with a one gallon jug of pale sour in the carboy.  That gives me a blend of 20% sour to 80% saison.  If I'm making a smaller batch, I'll usually make three gallons of saison, move it to a carboy, and then rack out and replace some proportion with the sour.  In some cases, this means racking out to fill a 1/2 gallon jug, and replacing with the same volume, i.e. roughly 15% sour to 85% saison.  In other cases, I've split a single half-gallon jug between two three gallon carboys, i.e. roughly 8% to 92%.

I can't always predict the final profile of the beer based on the way it tastes at blending.  One reason is that, if there is enough residual gravity left in either beer, there may be further fermentation afterwards.  Depending on the age of (and relative health of the yeast and bacteria in) each beer, the sourness will either increase rather quickly after blending, or increase more slowly in the bottle.  As with the blends made with my kettle sour, I've found that a small amount of acidic beer makes a quite noticeable difference to the perception of the final blend.  I would hesitate to go over 20-25% sour beer, unless I wanted to make something with a very pronounced acidity.  5-8% seems to be a good proportion for a background tartness, and 8-15% if you want something a little more pronounced without making the beer 'sour'.  Of course, all of this will be relative to the sourness of your acid beer, as well as your own palate.

So far I've usually let the beer sit in the carboy for at least a month before packaging, which gives it a chance to stabilize.  I have occasionally made blends at bottling, and its something I'd like to do more frequently.   The trick, of course, is getting a predictable level of carbonation after packaging, which means either ensuring that both components are as dry as possible before blending, or factoring in any further fermentation into how you calculate the amount of priming sugar.  (Jeffrey Crane's calculator is an excellent tool for this, but only if you can predict the terminal gravity of both components of the blend.)  The most interesting option---one that's inline with what many Belgian producers do---would be to rely solely on residual sugars in the blend for carbonation.  I haven't been brave enough to try this yet, but its something I'd like to do in future.  It certainly requires more patience, as the beer will need a longer period in the bottle to reach condition.  There is also the fear that the beer will over-carbonate, or fail to carbonate at all.

Old Batches

While writing this post, I took the opportunity to revist some previous batches of bière de coupage.  One recipe for which I've used this technique consistently is my buckwheat saison.  This is one of those beers where I'm looking for a more pronounced tartness to complement the fruit-forward flavours of the base, so five of the six batches I've made have had a ratio of 20% sour beer to 80% saison.  Some of the saisons underwent mixed primary fermentations, whereas other were fermented clean.

The batch I tried while writing this post was the third I made, and is almost a year old at this point.  It is very fruit-forward in its aroma and flavour, with lots of lemon up front (both in the flavour and acidity), and some more generic citrus and stone-fruit in the background.   The buckwheat still gives this one a fairly full body, along with great head retention, but the beer still finishes dry.  Its been pretty well received by most people I've given it to, and is one of my favourite batches.

The second was one of the spelt saisons I brewed a few months ago.  This one was aged with a small pitch of the Dupont Lochristi blend, and had approximately 1/4 gallon of ages sour blended in, to make up 8% of the final blend.  Both beers were fairly attenuated at blending, and I let the blend sit for a while before packaging, at which point it had reached 1.002.  I had hoped it might drop a little further in the bottle, but there's no sign of that yet.

At this point the beer has a noticeable tartness, but not one that dominates the rest of the beer.  There's is also still a slight tannic bitterness at the back end, which I rather enjoy, since it adds a bit of complexity to the finish.  The Lochristi strains are recognisable in the aroma and flavour of the beer, giving a soft fruitiness that is accentuated by the tartness.  My biggest criticism of the beer is that it is only moderately carbonated, where higher carbonation (modified by the softer mouthfeel of the spelt) would really help some of the flavours to pop out.  If I were to make this batch again, I would add the Lochristi strains along with the aged sour (or use a sour that had some of those strains), and package the beer at blending.  My hope would be that the flavour profile would gradually shift over time, and that the carbonation would steadily increase without becoming dangerous.

New Batch

While working on this series of posts, I also decided to make a bière de coupage that was a little different from the ones I've made before.  For the most part, I've tended to stick to fairly classic saison profile for the blended components, particularly in their hop profile.  This time I decided to go in a different direction, taking my basic spelt saison recipe, but using American hops for the flavour additions instead of something like EKG.  In the end, I went with Ahtanum, Amarillo, and Citra for the kettle hops (keeping additions fairly small), as well as a light dry-hop with Amarillo.

I blended in a small portion of aged sour from a pale solera as I racked the beer to secondary (probably around 5%, though I did it by eye), and let it sit for a few weeks before adding the dry-hops.  Once these had settled, I tasted the beer in preparation for bottling.  The dry-hop had given it a very perfumed aroma, with lots of citrus and tropical fruit, and a touch of funk underneath it.  This seemed promising, but I decided that the beer needed more tartness to make all of this jump out in the flavour.  With that in mind, I added an extra 1/2 gallon of aged sour to the batch at bottling (in the photo below, you can see the parts of the dislodged pellicle spiralling down through the glass jug).  I will give the beer at least three weeks before opening a bottle, and won't drink most of the batch until after I return from England at the end of the summer.  It will be interesting to see how much of the hop aroma survives at that time.

Grist: Pilsner (65.7%), Unmalted Spelt (23.9%), Vienna (10.4%)

Hops: EKG, Amarillo, Ahtanum, Citra

Yeast: Saison Blend (Yeast Bay Saison Blend II, Wyeast 3726)

O.G.: 1.046

IBUs: 28.1

ABV: 5.8%

That's it for this post.  In the next part of this series, I'll be writing about some rather special bières de coupage, made from home-brew blended with genuine lambic.

Bière de Coupage: Kettle Sours

Since writing the first post in this series, I've been slowly making my way through copies of the correspondence pages from early volumes of Le Petit Journal du Brasseur (provided by Dave Janssen of Hors Catégorie Brewing).  One common question about bière de coupage is whether there might be any shortcuts that would allow a brewer to produce them more quickly or cheaply than by buying or ageing beers for blending.  The answer to questions framed in this way is usually a resounding 'no': if you want anything of the complexity and character of an aged beer, you have to use a well-made beer of that sort. But the authors do often make suggestions about how brewers could accentuate or imitate certain elements of blended beers (e.g. by adding acetic acid), and its in that spirit that I planned the beers for this post.

Most of my attempts at making bière de coupage have involved using aged sour beers, usually drawn from a solera, because I was looking for both tartness and complexity.  But if the only thing you want is to add a bit of tartness to a beer, aged sours are not a necessity: all you need is a beer with a clean and pleasant acidity.  An increasingly popular and reliable way of achieving this is by a process of kettle-souring, i.e. pitching lactic acid producing bacteria into the wort in the kettle, boiling to kill them off once the desired level of acidity has been reached, and then fermenting the beer with a regular strain of saccharomyces.

From my experience, I'd say that beers made in this way tend to be a bit one-dimensional and boring by themselves, and I often find commercial versions to be overly acidic.  But these are all characteristics that make such beers excellent candidates for a certain kind of blending with clean beers: where the acid component can provide a controllable degree of tartness, the clean component can provide the further array of flavours we associate with beer, which are often suppressed (in the case of yeast-derived flavours) or overwhelmed in a straight-forward kettle sour.  This is essentially what Off Color does for their gose Troublesome, and what New Belgium does for their wheat beer Snapshot.

With that in mind, I had the idea of brewing a large batch of kettle sour, and storing it in a keg for regular blending.  My thought was that this would allow me to measure out different volumes of the acid beer as required: a few ounces if I just wanted to a small amount of tartness to a beer, or a gallon or more if I wanted some prominent acidity.

Kettle Sour

Grist: Pilsner (80%), Wheat Malt (20%)

Hops: EKG

Yeast: Safale US-05

O.G.: 1.042

IBUs: 20

ABV: 4.4%

Process

I made a litre starter for the Omega lactobacillus, and let this sit (without agitation) for 24 hours before pitching.  Since each half of the brew-day would be relatively short, I managed to fit them in across consecutive week nights.  On the first day I made the wort, doing a BIAB mash with as much of the total liquor as I could fit in my kettle, then liquoring down after mashout to reach my full boil volume.  At that point I raised the temperature up to just below boiling, then quickly cooled it to around 95°F before pitching the lactobacillus starter.  I wrapped it up in some insulation and a sleeping bag (the same stuff I use if I want to hold my mash-temperature for more than an hour) and left it to sit until the next evening.

The Omega blend performed as advertised, taking the wort down to 3.33 in around 18 hours.  Once I'd confirmed this drop in pH, the rest of the brew-day was quite straightforward: just a normal boil, cooling the wort, and pitching the yeast.  I was a little worried that the low pH would inhibit the US-05, but when I checked the next day there was visible activity after about 14 hours.

Once the beer had fermented out, I transferred it to a five gallon keg, added finings, and put it on my balcony overnight (the 'Chicago winter cold-crash') before transferring to a second keg the next day.  Its been sitting there under pressure ever since: whenever I need some for blending, I just attach the keg to some tubing and measure out the proportion I need.

The beer came out as expected: clean, lemony sourness, without much else going on.  My idea was to use it in varying proportions to add some degree of acidity to different beers, from a tart acidic bite at the end of an otherwise normal beer, to a pronounced but balanced sourness.

Blending

As of writing this post I have used this batch in three different beers, each with varying proportions of acid beer blended in.  For the first I made a dry stout, since I've been brewing them a lot anyway, and I thought it would do well with a small percentage of acid beer.  The second was a wheat saison, to which I was hoping to add a more noticeable acidity.  And third, a wheat beer, which would be the most acidic of the lot.

I came up with some rough percentages before brewing, but also took the time to test them after the beers had fermented out.  One thing I'll say is that this time around it was very clear to me that the perceived acidity increases once a beer is cooled and carbonated.  I tested these blends at rooms temperature, and in every case the final beer ended up a bit more acidic than I'd anticipated.

The proportions for each blend were as follows:

Dry Stout: 5% acid beer.

Wheat Saison: 12% acid beer

Wheat Beer: 33% acid beer.

Dry Stout

A dry stout seemed like an obvious candidate for this kind of blending, and as I mentioned in the first post of this series, there is considerable historical precedent , which is nicely captured in this rather poetic description of "first-class Irish stout" from the 1920s:

There is something at unspeakably seductive and evasive of true description about a first-class Irish stout, It is extraordinarily full and round, mellow and succulent. Yet is it bitter - but that somehow you don't notice. Behind it and enriching the whole lies that soupcon of strange lactic-like sub-acidity. 

The author continues in the same vein, suggesting that its this "strange lactic-like sub-acidity" that is the key to a great stout:

To the mind of the writer it is the will-o'-the-wisp sub-acidity that does the trick in Irish stout. Take it away and you've little left but a black, heavy, dry, but very soft and full mild ale with a lot of hops in it — nothing very characteristic or outstanding. Curious that no one has succeeded in fathoming and grasping that extraordinary suggestion of a rare old vintage wine — something lactic it exposes to us — hidden away in the chocolate-coloured depths. In the export variety you get too much of this sub-acid touch and consequently too little of the limpid polished fullness. But the home consumption product has a veritable perfection of nicety of balance in this respect : it is indeed a wonderful work of the Art of Brewing.

Of course, the beer being described was probably much stronger than the one I brewed, and the acidity likely came from a beer that had been 'vatted', rather than a pasteurized kettle sour.  Still, the basic idea is the same: some small amount of sour beer blended in to add a slight but noticeable acidity to the finish.

Grist: Golden Promise (57.6%), Torrified Wheat (17.4%), US 2 Row (11.5%), Roasted Barley (7.7%), Chocolate Malt (3.8%), Dark Crystal (1.9%)
Hops: EKG
Yeast: Wyeast 1318
O.G.: 1.034
IBUs: 33.2
ABV: 3.1%

Kettle Sour: 3-5%

I'm still working on this recipe, but I felt like the beer came out rather well.  The torrified wheat gives the beer a fuller mouthfeel that belies its very low ABV.  At test-blending the addition of 5% kettle sour seemed to mainly accentuate the bitterness while adding a slightly tart snap at the end of the palate.  However, once the beer was cooled the acidity became more prominent, giving the beer a more noticeable tartness.  I enjoyed it a lot, and the keg didn't last long (why would it, at 3.1% ABV?), but I felt there was room for improvement.  I wanted a little more roastiness and bite, so for the re-brew I increased the O.G. and bitterness, along with the percentage of roast malts, and added a small late addition of Challenger.  I also reduced the kettle sour down to about 3% of the blend.

Tart Saison

For the next beer, I wanted to try making a simple and drinkable saison with a touch of tartness.  To this end, I came up with a recipe for a wheat saison, fermenting it with The Yeast Bay's Saison Blend II and their Lochristi brettanomyces blend.  After primary fermentation was complete I blended the beer with around 12% of the kettle sour (proportions were roughly measured for this one), and allowed it to sit for another month while the brettanomyces and saison yeasts continued to ferment the residual sugars in both components of the blend.  Once it had reached a gravity I was happy with, I packaged it in heavy bottles with priming sugar and allowed it to continue fermenting for another three weeks.

Grist: Pilsner (75.5%), Wheat Malt (18.9%), Torrified Wheat (5.7%)
Hops: Saphir, Bramling Cross, Sterling
Yeast: Yeast Bay Saison Blend II, Lochristi blend
O.G.: 1.038
IBUs: 23.8
ABV: 4.4%

Kettle Sour: ~12%

The final beer is almost exactly what I was hoping for.  The aroma is very fruit-forward, with a mix of citrus from the saison blend and the distinctive aromas of the Lochristi strains.  The beer itself is crisp, tart, and very easy to drink.  Not tremendously complex, but with enough going on to keep you interested.  I think the tartness works particularly well with the more fruity yeast flavours, and I don't know if I'd like this beer as much if I'd used more phenolic yeast strains.  At first I felt the beer was too tart, but as its aged the edges have smoothed out a little and I'm enjoying the slight sharpness.  Still, I'd like to experiment with smaller amounts of acid beer for a more subtle tartness in the finish.

Tart Wheat Beer

For the final beer, I knew I wanted to use a larger proportion of kettle sour, so I decided to try making a wheat beer that I could serve quickly from a keg.  The base was a pretty standard wheat recipe, with lots of European hops rather than citrus and coriander.  I fermented with with Wyeast 1318---an odd choice perhaps, but it was what I had available.  I think in future I'd use a more characterful yeast here.  

I blended the beer in a keg, with two parts wheat beer to one part acid beer, letting it sit for a few weeks at room temperature and then hooking it up to the CO2 in my beer fridge.  I felt that the beer was a bit one-dimensional at blending, so at the least moment I decided to add a small dry-hop of Citra.  This ended up dramatically changing the character of the beer, which I think would have been a bit flat without it.

Grist: Pilsner (51.4%), Torrified Wheat (20.1%), Wheat Malt (14.3%), Munich (8.6%), Flaked Oats (5.7%)
Hops: Saaz Special, First Gold, Styrian Goldings, Citra
Yeast: Wyeast 1318
O.G.: 1.049
IBUs: 21
ABV: 4.8%

Kettle Sour: 33%

The photo on the left was taken quite early on, and the beer cleared up slightly over time, though it always had a bit of haze.  It was fairly tart, but I didn't think the acidity overwhelmed the rest of the beer, which seemed quite well-rounded and moreish.  I think the higher F.G. played a role here. The character from the dry-hop seemed to increase over time, and I wonder whether the acidity played a role in that.  Ultimately, it tasted like a dry-hopped kettle sour, but I found it much more drinkable than the straight-up kettle sours I've tried, which can be hard to stomach after a glass or two.  

I'll be making this recipe again this summer, using Safale T-58 in place of the Wyeast strain, and backing down on the proportion of acid beer to get something closer to a tart wit.  I think these higher proportions would work well in a gose or other adjunct-complimented sour.  Based on my experience with this beer, I think I definitely prefer a blend of clean and acid beer to a straight kettle sour.  If nothing else, it allows for more control over the acidity of the final beer.

Bière de Coupage: Contemporary Versions

For this second post in the series on bières de coupage, I'm going to survey some contemporary examples of such beers.   I contacted a number of breweries while writing this post, and I've included any information they provided below.  The selection of beers is far from exhaustive, and I'll continue to update this post with new beers, along with any more information I manage to uncover about the ones I've included.  I'll advertise any updates on this blog's Facebook page.  Besides the breweries themselves, some information in this post was provided by Dave Janssen of Hors Catégorie Brewing, and Andrew Addkison of The Farmhouse Obsession.

Beers Blended with Aged Lambic

As we saw in the first post in this series, merchants and blenders have long been able to buy lambic in bulk from lambic breweries for making their own blends.  At the time Laurent was writing, this would generally have been for producing faro. (Laurent does not mention gueuze, probably because he was writing before the glass bottles essential to the refermentation of gueuze were widely available).  Its worth flagging how this practice differs from that of modern blenders such as Tilquin and Hanssens, who purchase wort rather than lambic, and ferment and age it in their own barrels.  A few of the things I've read suggest that this wouldn't have been unheard of in the eighteenth and nineteenth century—a response to one letter published in Le Petit Journal du Brasseur suggested purchasing wheat beers from regions outside Brussels and aging them in casks as a cheaper alternative to purchasing lambic—but most of the material is about people buying lambic rather than wort.  Today's home-blenders, along with breweries wanting to blend their own beers with genuine lambic, depend on sale of this sort, whether it be the small quantities involved bag-in-a-box lambic, or the larger volumes required for commercial blending.  Such blends provide some of the best examples of modern bière de coupage, most being made by European breweries.

Perhaps the best place to start in surveying these beers is with Brasserie de la Senne, the brewery opened by Bernard Leboucq and saison historian Yvan de Baets.  Many of the beers produced by Brasserie de la Senne show the influence of Yvan's labouriously researched essay on the history of saison brewing, which describes the practice of blending old and young beer, pointing out that lambic was often purchased for just this purpose.  Given this background, and the close proximity of the Cantillon brewery, it should be no surprise that Brasserie de la Senne released a number of beers made in this way.  Sadly its been a while since the last one was produced (and I've never tried any of them), but perhaps the brewery's upcoming to move to a larger facility will provide new opportunities for making this kind of beer.

One of the most interesting things about those early releases is that two out of three used beers from De La Senne's regular line-up as component in the blend.  Crianza, for example, was made by ageing a blend of their golden blond ale Zinnebir with Cantillon lambic in oak barrels for nine months, and the first of their experimental series of 'Wadesda' beers was a blend of Jambe-de-Bois and lambic that was also aged in barrels.  Anyone familiar with these beers will know that, like most of the brewery's line-up, they have a pretty firm bitterness, something that (according to conventional wisdom at least) might be expected to clash with any tartness coming from the lambic.  In fact, though, this aspect of their flavour profile probably brings them closer to historic saisons.  Those were bières de garde in the literal sense of beers made for keeping, and as such were often heavily hopped, with the bitterness gradually decreasing as the beers aged.  (I found a couple of places in the correspondence pages from Le Petit Journal du Brasseur where authors warn brewers trying to rush the process of making a bière de coupage about a corresponding difficulty: that young lambic will be too bitter for blending.)

Reninge Bitter Blond/Bitter Blond a lambiek

You can see the same combination of heavily hopped beer and lambic in another Belgian example of bière de coupage, the beers made by Chris Vandewalle at Seizoensbrouwerij Vandewalle.  Vandewalle, like Yvan de Baets, has an active interest in the history of Belgian beer, one that shapes the beers he brews today.  Vandewalle's Oud Bruin is made by blending together young and old beer made at the brewery, but more interesting for our purposes is the Bitter Blonde a Lambic, which is made by blending Reninge Bitter Blonde with lambic from Oud Beersel.

Reninge Bitter Blond is probably somewhat close to the historical saisons and bières de garde made in the region.  It has a beautiful orange hue, reminiscent perhaps of old beers that underwent a four or five hour boil in copper kettles, and at 7% ABV it is certainly strong enough for long-term ageing.  The beer hopped primarily with English-type varieties grown in Belgium, and is strikingly bitter. It is open-cooled, and then open-fermented after yeast is pitched in a U-shaped trough re-purposed from cheese-making.  After the krausen drops, the beer is cold-conditioned for three or four months prior to packaging.  The bottle I drank was about a year old, and had a definite brettanomyces funk to it, reminding me strongly of this C19th IPA recipe that underwent a secondary fermentation by brettanomyces clausenii.

For the bière de coupage, Vandewalle blends in a small portion of Oud Beersel lambic at packaging, without adding any extra sugar for priming.  The bottles are then left to condition at the brewery for at least eight months before sale, in which time the wild yeast and bacteria from the lambic bring the blend to condition.   The bottle I drank was from November 2013.  It was still only mildly tart (and the tartness did not clash with any residual bitterness), but the contribution of the brettanomyces was very dramatic, giving the beer an aromatic complexity that was quite striking (especially since the base beer already had a lot going on).  [Information in the previous two paragraphs was provided by Dave Janssen, based on a visit to the brewery in 2016.]

Cuvée De Ranke

As with Brasserie de la Senne and Seizoensbrouwerij Vandewalle, its no accident that Brouwerij De Ranke makes beers using this old process.  A key part of their brewing philosophy involves "respecting old traditional methods, without ignoring new techniques", and when I asked Nino about the background for this beer he mentioned the tradition of ageing porter in oak vats, with its counterparts in the Oud Bruins and Flanders Reds of Belgium, along with the lambic brewers and blenders of the Pajottenland.  "Our beer is a mix of these 3 styles: we live between the two oud bruin regions and are big lovers of real lambic."

Nino describes the base beer for Cuvée De Ranke as "a very simple amber coloured beer with moderate bitterness (30 IBUs) that ages for a year minimum in stainless steel tanks or barrels".  Interestingly, he also told me that this base beer undergoes a mixed fermentation, though I'm not sure if this includes LAB or just brettanomyces.  This base is blended with 30% Girardin lambic prior to bottling, and aged further at the brewery before release: "after the blending the bacteria and wild yeasts of the lambic find new residual sugars in our beer and create a new fermentation/evolution, it's like lambic take's over within 4 to 6 month."   Production time for cuvée is at minimum 18 months, and for Kriek (the same beers aged on Cherries) it is 24 months. I am not clear on whether any extra sugar is added for priming, but the process Nino described certainly sounds similar to the process used by Chris at Seizoensbrouwerij Vandewalle, and (as we'll see) it marks a difference between these beers and some American versions made in a similar way.

A number of breweries outside of Belgium also purchase lambic for blending with their own beers, including Birra Del Borgo and Birrificio Del Ducato from Italy.  Both breweries have released blends of their regular saisons with lambic, and unlike some of the other breweries listed in this post, these beers seem to be more widely available in the US (at least, the parts I've visitied!), which presents the opportunity for side-by-side tastings

Duchessa/Duchessic

Del Borgo's Duchessa, a spelt saison, is a lovely beer in its own right and well worth seeking out.  The spelt gives the beer a full and fluffy mouthfeel, along with a slightly savoury note in the taste, and the bottles I've had have all had a quite remarkable fruity character that reminded me of apricots.  I haven't been able to find out much about the process used to make this beer, but I'll update this section as I learn more.

Duchessic is a blend of the same beer with 20% lambic.  The original release was made with lambic from the Cantillon brewery, and aged for a year before sale.  I do not know whether more recent blends also use Cantillon lambic, but even if they do, I suspect that the recent sale of Del Borgo to AB-InBev will mean that any future versions of this beer will source their lambic from elsewhere.  The bottles of Duchessic that I have tried have all been excellent, with a quite pronounced lemony sourness and a soft funk.  The beer is slightly thinner than the basic spelt saison, and often quite highly carbonated.

Nuovo Mattina/Beersel Mattina

Del Ducato's Nuovo Mattina is a spiced saison, and the pepper, ginger, and chamomile were all very apparent in the bottle I tried, with the spices giving the beer an almost numbing quality.  While I wouldn't say they were overdone, I've never had a spiced beer that I've really loved, and this beer didn't make me a convert.

Beersel Mattina, on the other hand, was something quite special.  The original batch was made with lambic from Drie Fonteinen, purchased after the failed thermostat destroyed large quantities of Armand's stock.  These days the beer is made with lambic from Oud Beersel, which makes up 18% of the final blend.  As with other European bières de coupage, the blending is done at packaging, and the beer continues to age at the brewery for up to twelve months before sale.  The bottle I had was fantastic: a similar lemony sourness to Duchessic, but balanced here by a fruity funk that had a distinctive 'berry' character.  The spices receded into the background, and were barely apparent in the finish of the beer, adding some nice complexity (I don't think I would have picked them out if I hadn't tried the clean version immediately prior to drinking this bottle).

Several other breweries have released versions of their beer blended with lambic—Burning Sky from the U.K., and Hill Farmstead being two favourites of mine—but I have never tried those particular beers, so I won't write about them here.  I will, however, update this section as I try any other notable blends.

Beers Blended with Aged Mixed Fermentation Sours

As modern breweries start to come back to the idea of bière de coupage, several have started to make blends using their own sour beers.  This is naturally an excellent option for breweries outside of Europe, for whom the purchase of aged lambic would be prohibitively expensive.

One brewery that has led the way in the renaissance of this technique is Jester King, who use it in a number of their beers.  The most prominent example is Das Wunderkind, a saison that is made by blending aged sour beer with hoppy young beer.  The brewery is quite forthcoming with information about their beers, and have already published the recipe for the base beer in this blend.  This aged saison has been released in the past as Das Uberkind, and is also used as a base for their second-fermentation fruit beers.

As far as I know, unlike the European breweries described above, Jester King tends to blend beers that are already very dry and basically done with fermentation.  This means that, though their beers certainly continue to evolve in the bottle, they are not relying on a further fermentation of the original beers for carbonation.  Garret Crowell told me that they "look for a nice level of acidity in the older beer", and mentioned that this can be a good use for a beer that has become overly acidic: "if a barrel-aged beer is too sour, it can be blended with non-sour beer to balance it".  The brewery generally uses about 10-12% aged sour beer in their blends, though they have used as much as 25% in the Dichotomous series.  Crowell says that the blended component is often subtle at the rates they use, "but over time, further subtle fermentation takes place and can increase acidity".  He adds that "the most apparent evolution is the increased presence of brettanomyces".

For Das Wunderkind, the brewery blends in 2 oak barrels of aged beer (118 gallons), ranging between anything from eight to twenty four months old, with 30 bbls (930 gallons) of freshly-fermented hoppy beer.  This blend is then dry-hopped, cold-crashed for a week, and then packaged.  The hop character resulting from the combination of young fresh beer and dry-hopping is one of the most striking features of Das Wunderkind.  Although it is not a uniquely American practice, the resulting beer shares something of its flavour-profile with my favourite American mixed-ferment saisons, beers like Jolly Pumpkin's Bam Biere or Crooked Stave's Vieille Saison.

Goose Island (and co.)

Once you become familiar with the concept of bière de coupage, it becomes apparent that quite a few American breweries are making beers with this process, especially as sour beers gain in popularity.  For instance, 20% of Goose Island's Sofie is aged in wine barrels with brettanomyces and citrus before being blended back into the base beer.  (I've been trying to find out more about their process, and will update this post when I do.)  What's more, a number of brewers who spent time working at Goose Island have gone on to deploy the technique in their own beers.  John Laffler of Off Color uses it in their gose Troublesome, which is a blend of a kettle-soured acid beer and a "really boring" wheat beer.  Brian Taylor, who is head brewer at an exciting new Chicago brewery called Whiner Beer Company, will be using it in one of their first releases, a saison called Le Tub that will include some lactobacillus-fermented acid beer aged in wine barrels.