You gotta love the folks at Yukon Brewing! I am amazed at how willing they can be to accommodate my crazy beer experiments. They have facilitated a number of my efforts to explore how beer changes and morphs under different conditions. They went out of their way to allow for a blind, side-by-side-by-side test of beer vs. can vs. keg effects (read here) and they gave me the opportunity to do a vertical tasting of their Old Ale, Lead Dog (read here). They have always been open, curious and not at all self-conscious about how it might make their beer look. They deserve full marks for that.

I mention this because a few weeks ago, Yukon Dave (Gardner, but no one cares what his last name is, right?) presented me with an opportunity. He found a bottle of Midnight Sun, their espresso stout, accidentally left in storage dating back to 2009. He also happened to have a 2012 bottle and a relatively new bottle around. He proposed I take all three and do a vertical tasting to see what happens over that period of time.

Now, Midnight Sun is 6.2% alcohol, so not really a cellar beer, meaning at five years old, it could be pretty nasty. But Dave was curious and I couldn’t turn down an opportunity for an experiment, ad extremum. So I gave it a shot.

But before I reveal the results, I want all of you to hear that Yukon are being extremely generous here – most breweries would have dumped the old beer and never told anyone it existed. They deserve kudos, not criticism. Whatever I say below about the older versions of the beer bear NO resemblance to the quality of their fresh beer and say NOTHING of their fastidiousness at cleanliness and sanitation. Beer is a volatile product. Even the best beer in the world (okay, maybe not Cantillon) will eventually fall apart. It is a fact of life, just like death and taxes.

I decided to start with the fresh version first (date: May 2014), as I need a baseline for the test. I did the 2012 version (date: August 2012) second and finished with the 2009 (date: July 2009). While I knew this might lead me to focus on the differences and compare to the baseline, it felt the best way to accurately gauge the aging effects.

The 2014 pours a deep, opaque black with a dense, moderately sizeable dark tan head. The aroma is strong with medium roast coffee accompanied by chocolate and a bit of dark graininess. The flavour offers up some dark chocolate up front with a burnt caramel accent. This is quickly overtaken by a pronounced coffee roast. There is a light fruitiness and it presents a surprisingly clean body overall. Linger is a soft coffee roastiness, like burnt coffee beans but balanced by a decent chocolate and malt sweetness. A more than decent coffee stout.

Turning to the 2012 version, the colour is the same, but the dark tan head doesn’t seem quite as dense as the 2014. Actually the beer appears less lively overall, with lower carbonation and a flatter impression. The aroma leans more toward molasses, dark sugar, some chocolate and some dark fruit notes, cherry and sherry. The coffee is barely perceptible. I am surprised at how much the coffee disappeared.

The flavour confirms this impression. The body is thinner, with a noted cherry and sherry edge. I also get raisin, almond, chocolate and a slight tart tang (which is ever so subtle). Some vanilla lurks in the background. Not at all unpleasant, I must admit. I also find the alcohol comes out a bit more. The dark fruit actually adds an interesting dimension to the beer. This version is drier and seems more like a barrel-aged stout in some respects.

Overall, it seems to have lost its fullness and its roastiness but it does maintain a pleasant character. If I sampled it on its own I think my impression would be that it is not a world beater, but still drinkable. I think it is only because I tasted the fresh one first can I see it deterioration.

Then there is the 2009 version. While it is still opaque black that is about all it has in common with the other two. It has almost no head at all, forming just a thin dark tan ring. It looks almost flat, with virtually no bubbles at all. The aroma is similarly flat. I get some cardboard, a bit of earthiness, some melted chocolate and lots of dark fruit and that is about all.

The flavour is no more appealing. Cardboard, some rich sherry, cherry and other fruits come across and not much else. I can’t find any chocolate. Oddly there is some roast, but it isn’t coffee. It is more astringent and thin and not particularly appealing. It gets some hints of tartness, but not really pronounced. also some woodiness, but mostly the beer just seems lifeless.

What is interesting about this beer is that I suspect an average person might drink this and think, hmm this is unusual but not so bad. There are still flavours that might seem attractive. Sherry and dark fruits. However for me, knowing what the 2014 version tastes like, I can see just how far this beer has fallen. It contains none of the flavours that make the fresh bottle enjoyable – the coffee roast, soft chocolate and nice balance.

So, what have we learned? We know that a standard strength beer can’t last five years – but I suspect we already knew that. I take two things away. First, two years is not necessarily a no-go zone for a dark beer. Yes, it was a completely different beer, but it wasn’t bad. If I hadn’t opened three beer at once I likely would have finished the bottle; it had enough positive characteristics that I could drink it. It was not a great stout, but remained an interesting beer.

Second, beer matures in funny ways. Sure, the five year old beer had fallen apart but if we look at the overall trajectory between the three, we find that some flavours disappeared while others came to the forefront. Depending on what we are looking for, those aging flavours – dark fruit, sherry, vanilla and woodiness – might be appealing and desirable. This is the source of why stronger dark beer become more attractive after a couple of years. Add a couple alcohol percentage points to this beer and I predict many people might prefer the 2012 version.

Thanks to Yukon for being willing to put well-past-their-prime beer on display in the interests of beer science. If you think you learned something from this column, then I think you should re-pay them by going out and buying a six pack of your favourite Yukon beer. It seems only fair.