Bière de Garde with Extended Boil

My first brew of 2016 was also my first attempt at making something like a classic
bière de garde.  I have a few malty saisons cut with red sours that could probably pass for interpretations of the style, but here I wanted to make something closer to the stronger, malt-forward beers described in Phil Markowski's Farmhouse Ales.
Initially my plan was to make something along the lines of the 'Bière de Garde - Artisanal Brewery Version' on p.89 of that book, which relies on an array of specialty malts 'to yield a greater complexity and depth of malt flavour'.  However, as I was flicking through the rest of the book, my attention rested on the following short note on simpler single-malt grain bills:

This approach to malt grist formulation might be more appropriate if a longer keeping time (six months or more) is desired for a bière de garde.  As the beer ages and slowly reacts with oxygen (ingress through the bottle closure) the malt character will intensify and come into its own over a period of six to twelve months.  A formulation containing a larger degree of specialty malts (Munich, Aromatic, Biscuit, etc.) may become 'too malty' over an equivalent aging period.

Since I'm planning on ageing this beer for quite a while, I decided to change my original plans and go for a much simpler grist.

Something else also caught my eye in the simpler recipe for a 'Bière de Garde - Large Brewery Version' on p.88.  In the notes below the recipe, Markowski says:

An extended boil (two or three hours) will add complexity and character.  This grist formulation will yield a bière de garde suitable for longer-term storage (greater than six months).

I'd been meaning to experiment with longer boils for a while, prompted in part by conversations with Andrew Addkison from The Farmhouse Obsession.  Boil-length and intensity was one of the ways in which traditional brewers could control the flavour profile of their beer without relying on the array of specialty malts we have access to today.  As Yvan de Baets mentions in his essay in Farmhouse Ales, longer brews were also characteristic of at least some historical farmhouse ales:

The boil lasted five to eight hours and sometimes up to fifteen hours "due to the generally accepted opinion that beer kept better the longer it boiled". This resulted in a deeper coloured wort, intensified by the fact that the copper boiling kettles were generally heated by open fire. (p.107)

Longer boils are also associated with traditional lambic brewing, and I think they might add some interesting complexity to my pale sour soleras.

With all this in mind, I decided to try making a bière de garde with a simple grist of 80% pilsner and 20% Golden Promise, hopefully getting some colour and complexity from an extended four and a half hour boil.  The planned O.G. was 1.075, with bitterness and hop character coming from some French Aramis hops.

The extended boil took some extra planning, since with my full-volume BIAB mash I couldn't fit all the liquor I'd need in the kettle.  The solution was simple, holding back some water until after the mash, then adding it back before the start of the boil.

I do my brewing on the stove-top, placing the kettle across two burners, which together provide enough heat for a moderately vigorous boil, as you can see in the following video:

I removed a small sample of wort at the start of the boil, and then roughly every 40-50 minutes afterwards.  As you can see from this picture, the change in colour over the course of the whole boil was quite striking.  The turbidity of the final sample (hops and protein) doesn't do full justice to its dark colour:



I fermented the beer using a kolsch strain (Wyeast 2565).  I'm also planning to add a small pitch of brettanomyces for a slow secondary fermentation, probably the Wyeast Clausenii strain.  Contemporary wisdom has it that brettanomyces doesn't really have a place in bière de garde.  Here's Gordon Strong on the topic in his new book:

[Bière de garde] is a widely misunderstood outside of France because of the condition of their exported beers. The style doesn't have a musty, cellar-like quality; that is something that comes from dried-out corks used in old bottles.  Some imported examples were fruity due to oxidation.

This is almost certainly right when it comes to contemporary versions of the style, but if it really does have its roots in French farmhouse brewing, a secondary fermentation by brettanomyces doesn't seem completely out of place in a beer intended for a long-term storage.  If nothing else, it will help to dry things out, and perhaps add some interesting complexity.  Since I'm not planning to enter this in any competitions, I don't care if its considered 'to style'.  I might even add a light dry-hop, or just use the whole batch for blending...