Thursday, 15 January 2015

Brewing long-aging beers - some guidelines.

A few months ago I announced my intention to start a short blog series on long-aging beer, in a post where I outlined a couple of my more recent vintage brews. This was followed by a review of THE book any brewer serious about brewing vintage beers (or collecting commercial vintage beers) must have in their library, In this, the third post in this series I will go over some of the rules for designing, brewing and aging these beers.

The ideas in this post are largely my own, but as I mentioned in the aforementioned book review, the reading of Patrick Dawson's "Vintage Beer" was key to crystallizing these ideas in my mind, so I'd like to encourage my readers once again to buy this amazing book.

This is going to be a long post, so the details can be found below the fold.

How vintage beers age

My favourite part of vintage beers is how their flavours change and mature as they age - every time you open a bottle (assuming you don't open them too often) the beer is a little different. Fresh malt flavours give way to sherry (if the beer is based on light malts) and port (if the beer is dark-malt forward). Fruity esters give way to dried fruits, phenols mellow and become tobacco/leather, and oak (if used) becomes ever more incorporated into the overall flavour. If the beer has some brett in it a whole new palate of flavours emerges - hop-derived compounds take on tropical-fruit notes; at the same time funky phenols develop providing a pleasant earthiness to the bre. A well-aged beer is truly a joy to drink.

All of this is driven by something brewers normally think of as the enemy - oxidation. What separates this oxidation from kettle and fermenter oxidation that ruin beers are a few main things:
  1. Alcohol content. Beers with ABV's above 8% age well; the alcohols will react with oxygen, forming flavourful aldehydes and other compounds. Below this ABV level, beers are unlikely to have the stability and legs to get through a prolonged aging*.
  2. Residual sugars. Long-aging beers need residual sugars - i.e. the beer after fermentation still needs to have some sweetness. Like alcohol, these sugars will react with oxygen; providing those sherry and port notes that are the classic characteristic I associate with vintage beers.
  3. Modest hop rates with beta-acid rich hops. Alpha acids oxidize poorly, forming cardboard-like flavours, so brewers will select beta-acid rich hops as the bittering and stabilization provided by the beta-acids will makeup for the gradual loss of alpha acids.
  4. Aging esters. Most long-aging beer styles are of English or Belgian origin - and this is no mistake. Both Belgian and British ale yeasts leave fruity esters in the beer; these same esters oxidize to taste much like the dried fruit equivalent - apricot & peach age to taste like...well dried apricot and peach. The stone-fruit (plums, cherries, etc) flavours often found in Belgian beers turn to dried figs, dates and raisins. These flavours blend seamlessly with the oxidized malt-flavours, creating a taste sensation that is unique and intoxicating. Note: the bannana esters of many German yeasts do not last.
*Sour beers are an exception to rule #1, with sours of 4-5% often ageing gracefully for decades. But these are a totally different beast in terms of the recipe formulation & brewing "rules", so I'm not going to address them here.

Some basic rules to follow

Regardless of the style of aged beer you are preparing, there are some basic rules you need to follow when brewing your beer:
  1. All the normal rules of good brewing apply. Don't skimp on the sanitation, cleaning, oxygenation of the fresh wort, etc, in the hopes that a long aging will resolve any issues. Beer that tastes good going into the bottle tastes good years later. Beer that has flaws will tend to get worse as time goes on.
  2. Top-quality ingredients are key. Patrick Dawson summed this up perfectly: garbage in - garbage out. Make sure your malt & hops are fresh and have been stored properly to limit oxidation. If brewing with extract (and yes, you can make fantastic vintage beers with extract), make sure it is a quality extract that has been stored properly. The last thing you want to do is start with poor-quality ingredients that have already developed unpleasant age/oxygen related off-flavours.
  3. Don't skimp on oxygenating the wort before you pitch the yeast, but once fermentation has finished avoid oxygen like the plague. If you can, secondary fermenters and bottles should be CO2 purged before putting your beer into them. We want slow oxidation to get those vintage flavours - the trickle of oxygen that diffuses through your carboy's stopper or the cap of your beer bottle is enough. If possible, keep your beer "alive" (i.e. don't filter out the yeast); live yeast will help to scavenge excess oxygen. Too much oxygen = flat-tasting beers if your lucky; if you're unlucky sucking on a piece of cardboard will be more pleasant than your beer.
  4. If you're pushing the yeast close too/past it alcohol limit there are some special things you may need to do in order to ensure that fermentation is complete without excessive off-flavour production. This will be a topic of my next post in this series, as it impinges directly on a post/brew-day that is the ultimate point of this series of posts...

Formulating a recipe

Formulating a recipe for a vintage beer doesn't need to be hard - any high-gravity ale that is not overly hoppy will do. English-style barleywines and Belgian quads are the kings of the vintage world, but many other styles work well. Russian Imperial Stouts and Imperial Porters age well for a year or two - and with a few little tricks can age much longer. Wee heavies, Scotch ales and the like also do quite well with prolonged aging.

Once you've narrowed in on a style you'll next want to tweak it to maximize its aging potential:
  1. Pick malts and a mash schedule that will give you a lower-fermentable wort - i.e. mash high, and don't be afraid of malts that leave behind a lot of dextrans. You'll need those residual sugars for the beer to survive the aging process.
  2. Modify the hop schedule:
    • Drop an aroma additions and keep flavour additions to a minimum. Aroma will disappear in a few months and most hop flavours don't last too long.
    • Make sure your bittering hops are high-beta acid hops. Alpha acids will not stand up to aging well, but beta acids will. My old rule (before I understood the role of beta hops) was "only use English hops"; this is a good guideline - Fuggles, EKG's, Willamette and Challenger all have favourable alpha:beta ratios. But non-UK hops do as well - Mt. Hood is excellent, as are most of the Nobel hops.
    • Remember, you are going to loose IBUs with age - so bitter more than you think you need to ensure there is enough bitterness after a few years.
  3. Pick an estery yeast. Generally, the classical UK and Belgian yeasts that match up with the non-vintage forms of the styles will work well. But be careful - too many esters can lead to too much dried fruit in the final beer.
  4. Think about adding brett. Not only was this normally found in classical examples of vintage ales, but it gives you the double-bonus of generating new and wonderful flavours while the beer ages while simultaneously giving you the best protection against excessive oxidation possible. I drank the last bottle of my first brett-aged beer ten years after brewday - and it was still delicious. Bretts are best added to the secondary for this purpose.
  5. Consider oak - but also consider its implications. Oak-derived flavours can add wonderful vanilla, coconut and other flavours to a beer. However, these flavours do not evolve much over time and do not fade quite as much as other flavours. A subtle oaking - if it fits the style - can be wonderful, but strong oak flavours can render a beer undrinkable after a year or two of aging.
  6. Be careful with dark malts. Dark malts lead to a more acidic beer, which in turn can drive yeast autolysis and the generation of meaty/blood-like flavours (which is unpleasant no matter how subtle). Either age your RIS and imperial porters for a year or less, or start with alkaline (e.g. Burtonized) water. There is a reason why Burton-on-Trent was the king of RIS brewing, and that reason was their hard (alkaline) water made long-aging dark beers possible.
  7. Minimize your use of wheat. Wheat proteins tend to fall out of the beer over time, which can leave the beer thin and bodyless if you have relied on the wheat for mouthfeel and head retention.
  8. Keep in mind, this is a strong beer you're preparing. Calculate the number of yeast you need with a calculator you trust (I like yeastcalc.co), and make sure you prepare that amount of yeast - if not more!

Brew day

So you've formulated a recipe, bought some good quality ingredients, and used a starter to get a good pitch of yeast. That means its time to light your banjo burners and brew some beer! As you may expect, there are a few key things you need to do while brewing.
  1. Follow your usual brewing procedures - this isn't the time to improvise; do what works consistently for you.
  2. Avoid oxidation during the brewing process. I know there is a lot of debate about whether hot-side aeration is a thing, but avoid it anyways. You cannot be too safe, and remember - minor flaws will grow over time.
  3. You'll likely find yourself working with more malt and water than  you are used to. Hopefully it all fits in your mash tun - if it doesn't, don't be afraid to add gravity using a high-quality extract.
  4. Long boil times can be a benefit - the Malliard reactions will create kettle flavours that age gracefully, plus a long boil may be needed simply to concentrate your wort to the desired gravity.
  5. If doing a long boil, hold back your hop additions - boiling hops for more than 90 minutes can extract some unpleasant grassy notes, and longer boils don't enhance hop utilization much over what you get with a 90 minute hop addition.
  6. When you are done brewing make sure you beer is thoroughly cooled before transferring it out of the kettle - hot-side oxidation at this point will kill your beers aging potential.
  7. Make sure that everything that touches your cooled beer is well sanitized - this is not the batch of beer you want to pickup an infection.

Fermentation & packaging

Managing your ferment is key to getting a beer that ages well. If you haven't fermented a high-gravity beer before you may not appreciate how difficult this can be. Make sure you oxygenate your wort well - then oxygenate it again. Pitch an appropriate amount of yeast; I'd recommend a pitch rate of 1 million/ml/oP, or ~25% more than you'd normally add to an ale. Fermentation temperature control is key - these big beers can really heat up, and especially for the English styles, this can be deadly to the beer. Use a fridge, cool room, or whatever technique you have, but keep the beer in the right temperature range.

If pushing your beer past 10% ABV there are some other things you can do to help your ferment - I'll cover these in a future post.

Once your beer has completed primary fermentation you'll want to move it to a secondary fermenter; this will allow more yeast to settle out (avoiding later autolysis) and begin the aging process. You want to avoid adding oxygen at this point, so if you can pre-purge the secondary before transferring beer. If adding brett, this is the time to do it. Cap the secondary with an airlock and put it somewhere at a proper aging temperature (i..e. at, or a little below, fermentation temperature) and let it sit for a few months to a year - but make sure the airlock does not dry out during that time. If oaking either do it near the end (a few weeks is enough), or add a small amount at the beginning. Don't waste time or money on dry hops - the flavours will disappear before you drink the beer.

When packaging your beer you have a few choices - I usually carb in a keg and bottle with a beer-gun, but you can bottle carb by adding sugar (and I'd recommend adding champagne yeast if the beers aged for more than 6 months). Cap with quality caps (oxygen barrier caps are fine - trust me, you'll still get the oxidation you're looking for), or with corks and cages. When storing the beer, try to keep it at or below fermentation temperature - keeping it above can produce additional off flavours that you do not want in the beer - plus cooler temperatures slow the aging process, leading to a nicer flavour profile than a warmer aging provides.

So that's the end of this (very long post). Over the next two posts I'll cover a few tricks for getting those extra-strong beers to ferment out completely, as well as have some fun with some Belgian-related math...

(yes, math can be fun)

Previous posts in this series

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