Jacques Marais 20 January 2024 BEER AND WOOD BARREL AGEING BEER

CASKS Cask is the generic term for all cylinder shaped wooden, staved vessels, held together with wooden or metal hoops and possessing flat ends or heads Originates from Old French “casque” or Spanish “casco” both meaning helmet

COOPER A cooper makes wooden barrels History: Dates back to ~2600 BC Egypt Celts perfected it with iron-working skills Romans then adopted it and it spread Medieval times: Highly skilled, well-paid family profession passed on Barrel Uses Dry storage of food and valuables Warfare: Gunpowder bombs Wine, Spirits, Beer: fermentation, storage, maturation and serving vessel

ANATOMY OF A BARREL Stillage

TYPES OF CASKS Cask Size Barrel 150 ltr 200 ltr Old English Average Cooper’s size Typical American Bourbon size Barrique 225 ltr French wine and later Congac. Carato/Caratelli in Italy Butt 500 ltr For Sherry, but used in whisky Foeder >1000 ltr Belgium (fuder in Germany). Gets much larger Hogshead 230-300 ltr European oak used in whisky. Quartercask = 160 ltr Pipe 522 ltr Used for port in Portugal. Slightly taller in shape Firkin 4-5 ltr Most common sizes of barrels used for serving Pin 20 ltr Kilderkin 82 ltr

TYPES OF WOOD USED American White Oak: • Mostly from Eastern USA with many species • (e.g. Chestnut oak, Oregan white oak) • White oak is used for barrels, Red oak is too permeable • Extensive use in Bourbon (required by law) and then whisky. • Lighter colour. More vanilla, caramel. European Oak: • Mostly from France with mainly 2 species: • Summer Oak, Durmast Oak, but some others • also UK, Hungary, Germany, Portugal • Smaller areas than US. Tress grows larger and older • Darker colour. More spice, wood, dried fruits, nuts, citrus. May add more dryness Other Woods: Acacia, Apple (Iron Brew), Ash, Beechwood, Birch, Cedar (pepper), Cherry (sweet), Chestnut, Cypress, Douglas fir, Eucalyptus, Juniper, Mizunara, Paulo Santo (very hard), Pecan, Red Gum Pine, Spruce, Walnut and many more…

BEER STYLES Typical styles: Historical: Porter and Stingo: Imperial Stout / Old Ale / Barley wine Anything! Tripel

SOUR BEERS Lambic • Wood neutral, but needed • Reduce oxygen exposure Flemish Red • Oxygen intake is required • Very large foeders Brettanomyces • Metabolises cellulose and hemicellulose • Cells grow in microporous wood • Brett character more complex with wood • Cleans up oxygen extracted

WOOD FLAVOUR IN BEER Fresh wood, vanilla, nuts, burnt sugar, toast, cacao, dark fruit, butterscotch, clove, smoke, coffee, chocolate, caramel, toffee • Aroma and flavour may differ • May impart a fuller mouthfeel and perceived sweetness • Perception that barrel aged beers are stronger • Some woods impart very different flavours Other / Off flavours - Fresh green aromatics and tartness from fresh or untreated wood - Acrid aftertaste or strong tannins - Ash from over charring - Sourness/Brett/infection from un-sanitised wood - Dry/bitter/fresh wood aftertaste - Could clash with some beer styles (wooded IPA?)

WOOD FLAVOUR BJCP 33A – Wood-Aged beer Aroma Varies with base style. A low to moderate wood- or oak-based aroma is usually present. Fresh wood can occasionally impart raw “green” aromatics, although this character should never be too strong. Other optional aromatics include a low to moderate vanilla, caramel, toffee, toast, or cocoa character from any char on the wood. Any alcohol character should be smooth and balanced, not hot. Some background oxidation character is optional, and can take on a pleasant, sherry-like character and not be papery or cardboard-like. Should not have added alcohol character. Flavour Varies with base style. Wood usually contributes a woody or oaky flavour, which can occasionally take on a raw “green” flavour if new wood is used. Other flavours that may optionally be present include vanilla (from vanillin in the wood); caramel, butterscotch, toasted bread or almonds (from toasted wood); and coffee, chocolate, cocoa (from charred wood). The wood and/or other cask-derived flavours should be balanced, supportive and noticeable, but should not overpower the base beer style. Some background oxidation character is optional, although this should take on a pleasant, sherry-like character and not be papery or cardboard-like. Mouthfeel Varies with base style. Wood can add tannins to the beer, depending on age of the cask. The tannins can lead to additional astringency (which should never be high), or simply a fuller mouthfeel. Tart or acidic characteristics should be low to none, and never distracting.

WOOD FLAVOUR – PREVIOUS FILL Previous fill Oak Barrels Bourbon Whisky Rum Wine Sherry Port Sake Tequila BJCP 33B. Specialty Wood-Aged Beer This style is intended for beer aged in wood with added alcohol character from previous use of the barrel. Bourbon-barrel or other similar beers should be entered here. Overall Impression A harmonious blend of the base beer style with characteristics from aging in contact with wood (including alcoholic products previously in contact with the wood). The best examples will be smooth, flavourful, well-balanced and well- aged.

WOOD CHEMISTRY Wood consists of: • Cellulose: Main structure of the wood (60-70%) • Mildly degraded by Brett • Hemicellulose: Group of large complex wood sugars • Heat yields Maillard reactions, caramelisation, browning, furfural, maltol • Toffee, caramel, maple, chocolate • Lignin: • Mild heat gives vanillin and phenolic aldehydes • High heat gives phenols, smoky, burnt or medicinal • Tannins: • Astringent, but reduced during heating, drying and maturation • Oxidative and can create acetaldehyde • Lipids: break down during light toasting forming lactones (coconut, fresh oak, vegetal, celery) Different types of wood have different make-up of the above Wood Exposure • Exposure to inside length of grains is preferred • Exposure to cut sides leads to astringency and acrid flavours Alcohol content • Cask strength spirits (>55% alc) react directly with the wood (e.g. lactol - tastes like rum) • Lower alcohol penetrates the wood faster (?)

FACTORS AFFECTING FLAVOUR AND EXTRACTION Surface to Volume Volume Litre Surface to Volume cm2/L 20 195 200 90 2000 42 10000 24 Drying Toasting Charring Byrrh plant foeder – 1mil ltr capacity Time • Depends on other factors • 1-3 weeks for small barrels • 1-6 months for medium size • Longer Sour/Brett beers • Or longer • Favour might plateau over time

DRYING THE OAK Air Drying • Takes 18-36 months left outside and covered • Easier to work with and more stable, less predictable • Oaky, vanilla, nutty Kiln Drying • Using heat with humidity and air-flow control • More resistant and predictable, but expensive • Higher moisture content and darker • Green wood, toasty, sweet

TOASTING FLAVOURS Toasting is simply heating the wood for a few hours at a specific temperature • Wood can be re-toasted at higher temperatures • Usually darkens the wood slightly • Temperature affects the flavour Toasting at home is easy • Wrap wood in kitchen foil • Leave in oven for 2-3 hours at desired temperature • Leave to cool Also sanitises the wood Repeat and mix different toasts? *For European Oak reduce heat by 15C

CHARRING – WHY AND HOW Charring is burning the outer layer of wood exposed to liquid Why Char the wood? • Adds a layer of charred carbon that acts as filter for impurities • Breaks open the grain to increase surface area and sanitises • “Resets” previous use barrel – used in whisky industry • Higher temperatures impart flavours of vanilla, caramel and smoke • Removes lactones (fresh wood), tannins (bitterness), sulphur Charring levels: • Level 1: 15 seconds – sweeter, campfire flavour • Used for shorter maturations • Level 2: 30 seconds – coffee, vanilla, spice. • Used to “finish” barrel • Level 3: 35 seconds – slightly higher with more flavour • Level 4: 55 seconds – More intense complex flavours • “Alligator char”: Rough pattern At home • Blowtorch works very well • Difficult to determine how long • Clean the ash off with a brush to avoid ash flavour • Inside a barrel???

FACTORS AFFECTING EXTRACTION AND FLAVOUR Type of wood Barrel condition and use Storage Temperature: Faster at higher and fluctuating temperatures Humidity: <65% water evaporation >65% ethanol evaporation (Angel’s share) Wood thickness: Liquids keep penetrating further leads to more extraction Wood manipulation e.g. added grooves Agitation speeds up extraction Tighter wood grain give spicy aromas vs. wider gives toasty roasty

WOOD IN BEER - CONSIDERATIONS Buying a barrel • Price • Requires some planning • Size and batch sizes • Tap is useful • Previous fill or new oak • Toasting level • Flavour or target style of beer • Long term view • Storage space • Wood expression fades over time • Sour barrel No Barrel • Chips & Spirals - unpredictable • Cubes – More control. Light/Medium/high toast • Staves – From a barrel. Self toasting & charring Requires sanitation via steam, chemicals or heat

BARREL SANITATION Barrel preparation • Add cold water • Add boiling water • Checks for leaks • Swells the barrel • Helps sanitise • Possibly also sanitise chemically depending on the barrel Chemically – Fill or half-fill and stir • Citric acid + Potassium metabisulfite (acidic) • Used for barrel storage • Sulphur dioxide – burnt sulphur used in sherry butts when dry • Sodium carbonate (alkaline) • Whisky: shake around and soak • Rinse • Repeat every few months depending on use Steaming – very effective • Higher temperatures than boiling water • Wallpaper steamer stripper (~£40) or other

RACKING BEER INTO THE BARREL Rack from the FV • Purge with CO2, rack as usual • Racking wand Reduce headspace • More surface exposure • Reduce risk of infection or oxidation

BARREL STORAGE AND BOTTLING Storage space: • Do not leave in the cold – leakage • Aromas and infections from surroundings slowly seep in • Humidity matters • Inside the house or heated outside Headspace • Headspace grows as beer penetrates the wood and evaporates • Not usually a problem, but purge with CO2 OR add fermentable Leaks: • Hammer the hoops down to tighten • Apply barrel wax • Distilled water and flour in a 1:4 ratio, then blowtorch • Toothpick – can make it worse Bottling • Directly from barrel if there’s a tap • Rack to bottling bucket • Don’t bottle, keg! The Vinnie Nail

BARREL EXPERIENCES - KEN

Breaking in a new oak barrel Available in various degrees of toasting but also virgin oak Fill with clean cold water and let stand for 48hours. Wood will swell and seal any stave gaps. When you let the water out - give it a taste. You will be surprised just how good it tastes. Once free of leaks, get yourself some beeswax to treat the exterior. Look out for sharp bits on the barrel hoops Getting whisky flavour into the wood. • may be an expensive foray. • For my 5l barrel I purchased around 3l of the cheapest whisky I could find. • turned the barrel every few days over the course of a few weeks to ensure the whole surface area got contact. • repeat this exercise (by keeping the decanted whisky in its original bottles) in between beers if you like. This also has the additional bonus of aiding sanitation. The angels will take some of whatever you put in there

Keeping a barrel (sanitised) in between beers Generally best to keep barrels wet. Replace one beer with the next beer! Storing with tap water long term will lead to prevalent mould and bacterial growth, Is okay for short periods but replace water every couple of days If no beer to go in, there are some options: • 0.1-0.2% KMS holding solution. After draining the barrel should then be rinsed out with a citric acid solution. Wood & Beer • Alternatively Winemaker magazine instead recommends a holding solution of 1/g citric acid and 1.5g/l KMS Storing a barrel dry is difficult because unless you ‘sulphur; it, it will still attract mould. Sulphuring is often done commercially. • Burn a sulphur wick inside the barrel which consumes oxygen and fills it with poisonous sulphur dioxide • Probably a bit OTT for the homebrewer. If you get spoilage from mould inside your barrel - relatively easy to get rid of. • Recommended treatment is a 24hour soak with 1g/l sodium percarbonate solution for mild spoilage. 3g/l for more serious problems. • After emptying this is then followed by a 24 hour soak with a 1g/l citric acid solution. Inspect barrels before re-used them after long periods in storage. • This can be more difficult in the homebrew scenario can’t take apart small barrels.

Keeping a barrel (with bugs) in between beers LAB Perpetual Old Ale project (what I did) After reducing the oak character of the barrel with the passage of several different clean beers, it finally held a 1.092OG old ale blended with the dregs propagated from bottles of 2023 Dark Star (Gales’) Prize Old Ale. The aim was to store the old ale in the barrel for several months to take on a little oak character as well as receive oxygen to encourage the brettanomyces in the POA dregs. But foremost the aim was to inoculate the barrel with this culture so that it could be used again, and again without having to re-culture the dregs. The ultimate desire being to preserve that ancient Gales’ strain! - Inoculated some beer of which I was not fond with the POA dregs • Left for several months in a DJ. • Transferred to barrel when ready • Kept in the barrel for a month so that microflora could work their way into the wood. - After emptying the dregs I filled the barrel with 1.092 old ale which I had brewed • Made sure to leave a bit of headspace for the expected secondary fermentation. • Dregs went back into DJ and were fed. - After 7 weeks the beer had dropped from 1.019 to 1.010 and had taken on a distinctive bretty character with a pronounced level of acidity not dissimilar to Flanders ales. • Thoughts turned to how to keep the brett and microflora alive for future batches whilst the barrel was empty of beer.

Keeping a barrel (with bugs) in between beers LAB Perpetual Old Ale project (what I did) - During research I found it difficult to glean information on how to keep a barrel in between beers so it retains all the microflora. • Couldn’t blitz with KMS • Couldn’t sulphur • Would probably have had the effect of killing off any ‘house strain’ that developed in the barrel. - Reading about what wineries do I discovered that citric acid promotes brettanomyces so they avoid using it • what if I just stored the barrel full with citric acid solution to a pH of 2 or 3? • The acidity would be high enough to prevent growth of (most) mould or bacteria but would allow the brett to survive. - Emptied the Perpetual Old Ale and rinsed out with warm water to get rid of any lees • Filled with citric acid holding solution for approximately 4 months (30.06 to 27.10) • Refilled it again with a basic Flanders Red type beer (fermented clean) - This would be my test to see whether the barrel would inoculate the next beer. - It only took a couple of weeks to notice that the new clean beer had begun to take on traces of the expected character from the barrel. So my second beer re-fermented in the barrel with the Gales’ strain is now on the way.

1) Inoculating the barrel with the lovely Gales dregs 2) Emptying the Gales dregs from the barrel after a few weeks 3) Kegged old ale pushed to inoculated barrel 4) First sample of POA 5) Finished POA racked to keg 6) 2nd beer from inoculated barrel

BARREL EXPERIENCES - GUY My Experience with Ageing Beer in a Wooden Barrel ● Oak Barrel from Celtic Timber. Volume is around 22 liters. (www.celtictimber.co.uk) ● Is a former whisky barrel. They reshape the staves and recouper the barrel. ● Made two beers so far and one is currently in the barrel ● Beer #1: RIS. Infection ● Beer #2: RIS. Big improvement. ● Managed to let it dry out last spring ● Beer #3: Attempt at Stingo ● Long term plans

BOOKS AND REFERENCES Books Wood & Beer Youtube: How a barrel is made https://youtu.be/e_GxHtenhms?feature =shared Charring a barrel https://www.youtube.com/watch?v=Jqo pSMvCXv0

QUESTIONS

BARRELS AND THE WHISKY INDUSTRY Whisky terms • New oak/Virgin oak/First use: No previous fill • First fill: with whisky, but actually ex-bourbon or ex-sherry • Refill cask: After first fill whisky –used 4 times then discarded • Cask strength: No dilution. Usually filled at 65-80% alcohol • Marriage cask: mixture of different whiskies blended for 6 months in large barrel • Re-charring: Rejuvenates the cask • Single cask: Only one cask during the whole maturation • Single malt: 100% malt whisky from single distillery • Blend: Mixture of single malt and grain whisky Whisky vs. Whiskey?

LONDON BEER FLOOD The London Beer Flood was an accident at Meux & Co's Horse Shoe Brewery, London, on 17 October 1814. It took place when one of the 22-foot-tall (6.7 m) wooden vats of fermenting porter burst. The escaping liquid dislodged the valve of another vessel and destroyed several large barrels: between 128,000 and 323,000 imperial gallons (580,000–1,470,000 L; 154,000–388,000 US gal) of beer were released in total. The resulting wave of porter destroyed the back wall of the brewery and swept into an area of slum dwellings known as the St Giles rookery. Eight people were killed, five of them mourners at the wake being held by an Irish family for a two-year-old boy. The coroner's inquest returned a verdict that the eight had lost their lives "casually, accidentally and by misfortune". The brewery was nearly bankrupted by the event; it avoided collapse after a rebate from HM Excise on the lost beer. The brewing industry gradually stopped using large wooden vats after the accident. The brewery moved in 1921, and the Dominion Theatre is now where the brewery used to stand. Meux & Co went into liquidation in 1961.

Breaking in a new oak barrel • New barrels are available with various degrees of toasting on the inside, but you can also get them in virgin oak. • Fill with clean cold water and let stand for 48hours. This is to allow the wood to swell and seal any stave gaps where leakage could occur. Ignore the instructions about not hammering in the bung and the wooden spigot - you’re going to need to give them a little bit of a tap to ensure they make a seal. • When you let the water out - give it a taste. You will be surprised just how good it tastes. - You’ll start to question why oaked water isn’t a thing! • Once free of leaks, get yourself some beeswax to treat the exterior. Take care when rubbing into the wood with your hands as the metal barrel hoops sometimes have sharp bits on them • If this is virgin oak you may want to get some whisky flavour into the wood. If you do - depending on the size of the barrel - this may be an expensive foray. For my 5l barrel I purchased around 3l of the cheapest whisky I could find and poured it in, then I turned the barrel every few days over the course of a few weeks to ensure the whole surface area got contact. You can repeat this exercise (by keeping the decanted whisky in its original bottles) in between beers if you like. This also has the additional bonus of aiding sanitation. • When it’s time to remove the whisky you’ll find there’s a bit less than you put in (the so-called angels’ share) due to absorption and evaporation. This will also happen to any beer you put in there so have some ‘spare’ for topping up when brewing to fill a barrel.

Keeping a barrel (sanitised) in between beers It’s generally best to keep your barrels wet and that usually means when one beer leaves it is immediately replaced with another beer after going through your cleaning and sanitation process. • Storing with tap water long term will lead to prevalent mould and bacterial growth, although this is okay for very short periods (not the mould growth, that’s never okay!) and the water should be changed at least every second day. If you don’t have another beer to go into it you either store it dry with a sulphur treatment or with a 0.1-0.2% KMS holding solution. I found however that the recommended KMS ratio did not work and still allowed mould to grow. It is possible I was getting my calculation or process wrong - You do need to make sure the KMS is well-mixed and there is nothing wrong in theory in just upping the concentration for belt and braces. After draining the barrel should then be rinsed out with a citric acid solution. (Wood & Beer ref) As an alternative, an article on Barrel Care techniques in Winemaker magazine instead recommends a sulphur & citric acid solution of 1/g citric acid and 1.5g/l KMS as a holding solution. • Storing dry is unfortunately not as simple as removing the bung and faucet and letting it air - unless you have somewhere that is dry and warm to store it - otherwise it will still attract mould. • A commercial method of dry storing is sulphuring. Sulphuring involves burning a sulphur wick inside the barrel which consumes oxygen and fills it with poisonous sulphur dioxide which will kill any bacteria and not allow mould to grow. You then replace the bung and check (VERY carefully as it is an irritant to the eyes nose and throat) every few weeks for sulphur aroma. Topping up if necessary. Safe to say this is probably a bit OTT for the homebrewer. If you get spoilage from mould inside your barrel, do not fear as it is relatively easy to get rid of. Recommended treatment is a 24hour soak with 1g/l sodium percarbonate solution for mild spoilage or up to 3g/l for more serious problems. After emptying this is then followed by a 24 hour soak with a 1g/l citric acid solution. • It goes without saying that barrels need to be inspected before being re-used after long periods in storage although this can be more difficult in the homebrew scenario as you generally can’t remove the head or any of the hoops and staves if you wanted to take one apart. All you have is a bunghole and a faucet hole - one to shine a torch down and the other to have a look around! I tried to use a tiny dental mirror for looking around inside my barrel but the hole is still too small. I’m thinking of somehow attaching a battery- powered LED bulb to the handle of the mirror so it reflects around the barrel.

Keeping a barrel (with bugs) in between beers This is what I did • After reducing the oak character of the barrel with the passage of several different clean beers, it finally held a 1.092OG old ale blended with the dregs propagated from bottles of 2023 Dark Star (Gales’) Prize Old Ale. The aim was to store the old ale in the barrel for several months to take on a little oak character as well as receive oxygen to encourage the brettanomyces in the POA dregs. But foremost the aim was to inoculate the barrel with this culture so that it could be used again, and again without having to re-culture the dregs. The ultimate desire being to preserve that ancient Gales’ strain! A few LAB members have been carrying out their own variations on the idea that we have named ‘Perpetual Old Ale’ • Before all that, I first inoculated some beer of which I was not fond with the Prize Old Ale dregs, leaving it for several months in a DJ. When I decided it was ready I transferred it all to the barrel and left it for about a month so that the brett and any other microflora would work their way into the wood. In the meantime I brewed a very strong old ale. •The dregs were emptied from the barrel straight back into the DJ whereupon the culture was fed (topped up to the neck with some mediocre beer) and returned to under my stairs for future use. I then filled the barrel with some of the old ale which I had brewed (leaving 15l of clean/virgin old ale in a cornie under pressure for blending back later) making sure to leave a bit of headspace for the expected secondary fermentation. • After 7 weeks the beer had dropped from 1.019 to 1.010 and had taken on a distinctive bretty character with a pronounced level of acidity not dissimilar to Flanders ales. Initial success! But then thoughts turned to how to keep the brett and microflora alive for future batched whilst the barrel was empty of beer.

Keeping a barrel (with bugs) in between beers This is what I did • When researching for my part of this LAB project I found it difficult to glean information on how to keep a barrel in between beers so it retains all the microflora. I didn’t want to blitz it with concentrated KMS solution or resort to sulphuring as that would probably have had the effect of killing off any ‘house strain’ that developed in the barrel. • Noting that wineries tend to avoid citric acid because it promotes brettanomyces I hit upon the idea - what if I just stored the barrel full with a 5% citric acid solution? The pH would be low enough to prevent growth of (most) mould or bacteria but not strong enough to wipe out the brett and it may even have a beneficial effect. • After emptying the Perpetual Old Ale, my barrel was rinsed out with warm water to get rid of any lees before being filled with the above holding solution for approximately 4 months (30.06 to 27.10) before it was filled again with a basic Flanders Red type beer (fermented clean) - This would be my test to see whether the barrel would inoculate the next beer. • It only took a couple of weeks to notice that the new clean beer had begun to take on traces of the expected character from the barrel. So my second beer re-fermented in the barrel with the Gales’ strain is now on the way.