Changes

French oak (''Quercus sessilis''/''Quercus petraea'' and ''Quercus robur'') contributes comparatively more [https://en.wikipedia.org/wiki/Trans-3-Methyl-4-octanolide trans-3-Methyl-4-octanolide] while American oak contributes more [https://en.wikipedia.org/wiki/Cis-3-Methyl-4-octanolide cis-3-Methyl-4-octanolide] to beer .<ref name='Review of oak aging for wine'>[http://www.sciencedirect.com/science/article/pii/S092422440600015X Review of quality factors on wine ageing in oak barrels. Garde-Cerdan and Ancin-Azpilicueta (2006)]</ref>. These lactones both contribute a coconut character but the cis-lactone has a much lower flavor and aroma threshold ,<ref>[http://www.sciencedirect.com/science/article/pii/S0023643805000150 Effect of oak barrel type on the volatile composition of wine: Storage time optimization. Garde-Cerdan and Ancin-Azpilicueta (2006)]</ref>, therefore American oak barrels may give more of a lactone flavor and aroma impact. ''Q. sessilis'' is more common in wine aging and ''Q. robur'' is more common for cognac barrels .<ref name='Review of oak aging for wine'/>

(''Quercus petraea'', or commonly Sessile Oak .<ref>[https://en.wikipedia.org/wiki/Quercus_petraea ''Quercus petraea''. Wikipedia. Retrieved 06/16/2018.]</ref><ref>Brandon Jones. Private correspondence with Dan Pixley. 06/16/2018.</ref>)

Chestnut (''Castanea sativa'') can be a cheaper alternative to oak for barrels. Chestnut barrels are used by some lambic producers (though generally most lambic barrels are oak). Chestnut allows more gas permeability than oak, and therefore will allow more oxygen transfer than a comparable barrel made out of oak.<ref>[http://link.springer.com/article/10.1007/s00217-010-1292-9 Effect of aging in new oak, one-year-used oak, chestnut barrels and bottle on color, phenolics and gustative profile of three monovarietal red wines. Gambuti et al., 2010]</ref>

Oxygen ingress will vary greatly even between the same type of barrels .<ref name="amaral_barrels">[https://www.facebook.com/groups/MilkTheFunk/permalink/1988872771140927/?comment_id=1989673027727568&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Justin Amaral. Milk the Funk Facebook post on measuring oxygen in barrels. 02/15/2018.]</ref>.

Sherry barrels typically have the most oxygen ingress .<ref name="amaral_barrels" />.

Spirit barrels typically have less oxygen ingress than sherry barrels, but more than wine barrels. This also depends on the condition and char level of the spirit barrel .<ref name="amaral_barrels" />.

Wine barrels typically have less oxygen ingress than spirit and sherry barrels .<ref name="amaral_barrels" />. A standard 60 gallon Bordeux Chateau barrel weighs around 100 pounds (50 kg) empty, and about 600 pounds (275 kg) full .<ref>[http://socialvignerons.com/2016/06/27/anatomy-of-a-wine-barrel-parts-sizes-infographic/ Julien Miguel. "Anatomy of a Wine Barrel: Parts, Sizes, Infographic". Social Vignerons website. 06/27/2016. Retrieved 07/31/2018.]</ref>.

French wine barrels will have their hoops secured into place by nails. If the staves need to be tightened during swelling, then the nails must be removed. The nails can be removed with pliers or a hoop driver so that the hoops can be tightened. After tightening, the nails can be hammered back in, although some brewers just leave the nails out permanently. Justin Amaral recommends buying nails from Barrel Builders as they are reportedly easier to remove . <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1963764150318456/?comment_id=1963786806982857&comment_tracking=%7B%22tn%22%3A%22R%22%7D Joseph Kearns, Justin Amaral, and Andrew Zinn. MTF thread about tightening hoops on French oak barrels. 01/23/2018.]</ref>.

A number of wood products are available to homebrewers to get wood characteristics without using a barrel. While barrel flavors are generally not the primary goal of funky beer brewers who use barrels for fermentation and aging, wood can contribute some of the additional characteristics that barrels offer (such as mouthfeel influences) and can also be used to house microbes in a similar way to a barrel (Vinnie's dimebags). The most common non-barrel wood products available to brewers are oak based. Advantages of using these products over barrels include reduced cost, ease of use, and a more efficient use of the wood (the entire surface of the wood is exposed to the beer as opposed to only 40% of a barrel's surface area) <ref name="Cioch‑Skoneczny_2022">[https://link.springer.com/content/pdf/10.1007/s00217-022-04143-3.pdf Influence of oak chips addition on the physicochemical properties of beer. Monika Cioch‑Skoneczny, Mateusz Bajerski, Krystian Klimczak, Paweł Satora, Szymon Skoneczny. European Food Research and Technology. 2022. https://doi.org/10.1007/s00217-022-04143-3.]</ref>.

Alternative vessels include amphorea (also known as "Kvevri" in Georgian wine making <ref>[https://en.wikipedia.org/wiki/Kvevri "Kvevri". Wikipedia. Retrieved 11/13/2020.]</ref>) and food-safe concrete vessels used in wine making.

* [https://www.facebook.com/groups/MilkTheFunk/permalink/1247189481975930/ MTF amphora thread] and [https://www.facebook.com/groups/MilkTheFunk/permalink/1455483491146527/ this MTF thread] and [https://www.facebook.com/groups/MilkTheFunk/permalink/1433946813300195/ this MTF thread]and [https://www.facebook.com/groups/MilkTheFunk/permalink/3830338453661007/ this MTF thread].* [https://www.facebook.com/groups/MilkTheFunk/permalink/3839009346127251 MTF thread on fire temperature for reduced porosity of amphora.]

First, smaller volumes mean a greater surface area to volume ratio. This means that both flavor extraction from the barrel will be faster and O2 pickup will be greater (as oxygen penetration is tied to the barrel's surface area). Both of these factors make these small barrels attractive to craft distillers as they can shorten the aging time for certain flavor developments, but for the homebrewer looking to produce long-aged mixed-fermentation beers with no barrel flavor impact to supportive barrel character rather than strong barrel character, this is not ideal. The barrel character can be partially stripped by repeated use and soaking with water. One approach to this is to fill the barrel with hot water and allow it to cool overnight. The cooling will extract a lot out of the barrel, which can then be discarded. Because many of the small barrels available to homebrewers are derived from distilleries and therefore may be more likely a heavier toast level, it may take longer to remove the character of the wood and a progression of beers may be needed to make the barrel appropriately neutral for long aged sour beers <ref> [http://www.stitcher.com/podcast/basic-brewing-radio/e/082715-barrel-progression-experiment-40269155 Basic Brewing Radio barrel progression]</ref>. Shortening the residency time of beer in smaller barrels can also reduce the effects of oxygen pick up (which results in acetic acid and ethyl acetate) and barrel wood character.

The environment in which smaller sized barrels are housed can play a role in how much oxygen enters the barrel. Temperature shifts within the barrel form a vacuum that causes air to get sucked in. In drier regions with low humidity, and regions that are hotand low in humidity (under ~30% on average), barrels can dry out and evaporate faster.

in progressGeneral:* [https://www.barrelsdirect.com/barrel-inspection-5-point-barrel-inspection-process 5 Point Barrel Inspection Process.] 

* [https://www.facebook.com/groups/MilkTheFunk/permalink/3025910550770472/?comment_id=3026152757412918&reply_comment_id=3027926890568838 Alex Buck describes the barrel cleaning process for pyramid stacked barrels at Black Project.](Dead Link for now)

Heat has been established as the most reliable way to sanitize surfaces, with ''Brettanomyces'' beginning to die at around 37°C <ref>[https://pubmed.ncbi.nlm.nih.gov/15996781/ Thermal inactivation of the wine spoilage yeasts Dekkera/Brettanomyces. José António Couto, Filipe Neves, Francisco Campos, Tim Hogg. 2005. DOI: 10.1016/j.ijfoodmicro.2005.03.014.]</ref><ref name="Nunes de Lima 2020">[https://www.sciencedirect.com/science/article/abs/pii/S0740002020302069 Survival and metabolism of hydroxycinnamic acids by Dekkera bruxellensis in monovarietal wines. Adriana Nunes de Lima, Rui Magalhães, Francisco Manuel Campos, José António Couto. 2020. DOI: https://doi.org/10.1016/j.fm.2020.103617.]</ref>. The complete thermal death of ''Brettanomyces'' in wines has been reported to be accomplished at 50°C for 5 minutes. <ref>[https://pubmed.ncbi.nlm.nih.gov/15996781/ Thermal inactivation of the wine spoilage yeasts Dekkera/Brettanomyces. José António Couto, Filipe Neves, Francisco Campos, Tim Hogg. 2005. DOI: 10.1016/j.ijfoodmicro.2005.03.014.]</ref><ref name="Nunes de Lima 2020" />. Sanitizing barrels that are infected with ''Brettanomyces'' or other beer/wine spoilers is notoriously difficult, and some believe it to be impossible. While two previous studies ([http://www.ajevonline.org/content/62/4/519 Schmid et al. 2011] and [http://www.ccsenet.org/journal/index.php/jfr/article/view/24315 Barata et al. 2013]) found that steam was not effective at sanitizing oak, these studies have had their experimental designs criticized by other presumably better designed more recent studies ([https://www.ncbi.nlm.nih.gov/pubmed/25989358 Fabrizio et al. 2015] and [http://www.ajevonline.org/content/early/2018/05/23/ajev.2018.18024 Cartwright et al. 2018]). For example, Schmid et al. (2011) inoculated oak chips with nutrient broth instead of using barrels that represented real-world conditions, and Barata et al. (2013) only applied steam for 10 minutes <ref name="Cartwright_2018">[http://www.ajevonline.org/content/early/2018/05/23/ajev.2018.18024 Reduction of Brettanomyces bruxellensis Populations from Oak Barrel Staves Using Steam. Zachary M. Cartwright, Dean A. Glawe, Charles G. Edwards. 2018. DOI: 10.5344/ajev.2018.18024.]</ref>.  In contrast, Fabrizio et al. (2015) and Cartwright et al. (2018) found that it is possible that steam is an effective way to kill all ''Brettanomyces'' in oak barrels that previously held ''B. bruxellensis'' inoculated wine. Fabrizio et al. (2015) proposed that the most effective and preferred method is to heat the inside of the oak barrel to at least 140°F (60°C) for 20 minutes with hot water or steam. This was found demonstrated to be an effective way of killing ''Brettanomyces'' that was found growing as deep as 8 mm within the wood of 3-year old barrels infected with ''Brettanomyces''. Note that this might not be hot enough to kill other heat-tolerant microbes; however, these heat-tolerant species tend not to be able to survive in beer. Steam treatments that are higher in temperature and longer should not present any concernsto the barrels themselves; however, if hot water is used instead of steam then the longer the water is exposed to the barrel the more character from the barrel that gets removed by the water <ref>[https://www.ncbi.nlm.nih.gov/pubmed/25989358 Heat inactivation of wine spoilage yeast Dekkera bruxellensis by hot water treatment. Fabrizio, Vigentini, Parisi, Picozzi, Compagno, Foschino. 2015.]</ref><ref name="Agnolucci_2017">[https://link.springer.com/article/10.1007/s11274-017-2345-z Brettanomyces bruxellensis yeasts: impact on wine and winemaking. Monica Agnolucci, Antonio Tirelli, Luca Cocolin, Annita Toffanin. 2017.]</ref>.  Cartwright et al. (2018) confirmed these results and reported that as little as 12 minutes of steam was enough to eliminate ''Brettanomyces'' in both French and American oak wine barrels that were previously inoculated with ''B. bruxellensis'' for 6 to 7 months. In general, the French oak barrels had larger populations of ''B. bruxellensis'' than the American oak barrels, likely due to American oak being less dense. The staves closest to the bungholes had the largest population of ''B. bruxellensis'' 0-4mm into the wood, likely due to better access to oxygen, but there were also large populations within the bottom staves which were found at deeper levels into the wood (5-9mm deep). Oak barrels with heavy toast levels tended to have higher populations perhaps due to more cracks in the staves or more availability of cellobiose. The French barrels required 12 minutes and the American oak barrels required only 9 minutes at 131°F (55°C)to eliminate all ''B. bruxellensis'' from even the deepest points into the oak where ''B. bruxellensis'' has been found (up to 9mm). Before this was achieved, it took 4 minutes to reach this temperature at 9.5mm into the oak. They could not culture ''Brettanomyces'' from the oak even after incubation of stave cross-sections in WRM for 60 days. Hot water was also reported by the same research group to effectively eliminate ''Brettanomyces'' from oak barrels, although it took longer (70°C for 30 minutes or 80°C for 20 minutes). The researchers expressed the opinion that the effect of heat treatment on barrel quality needs to be researched. Although it has been reported that extensive heating can destroy desirable oak flavor compounds such as guaiacol, 4-methylguiaicol, furfural, lactones, eugenol, and vanillin, degradation of these compounds requires temperatures between 248°F (120°C) and 365°F (185°C) for 1 to 6 hours, so significant degradation of desirable oak flavor compounds is not expected to occur with 12 to 20 minutes of 131°F (55°C) to 140°F (60°C) of steam pasteurization <ref name="Cartwright_2018" /><ref>[https://search.informit.com.au/documentSummary;dn=008738882146548;res=IELHSS Zachary Cartwright and Charles Edwards. "Wine maturation: What can a winemaker do about 'Brettanomyces bruxellensis' present in oak barrels?" Wine & Viticulture Journal. Volume 34 Issue 4 (Spring 2019).]</ref><ref>[https://www.journals.ac.za/index.php/sajev/article/view/3008 Edwards, C.G. and Cartwright, Z.M. (2019) Applicatio nof heated water to reduce populations of Brettanomyces bruxellensis present in oak barrel staves. Sth. Afr. J. Enol. Vitic. 40:1-8.]</ref>.

Swaffield and Scott (1995) found that the yeast and lactic acid bacteria belonging to the genre ''Lactobacillus'', ''Pediococcus'', and ''Leuconostoc'' that were in cider penetrated oak blocks up to 1.25 cm after 9 weeks of being submerged 1 mm into the cider, so it is possible that yeast and bacteria can grow deeper than 8 mm into oak, although these oak cubes were made from virgin oak vats and might not accurately reflect what would be found if these same microbes were inoculated in oak barrels <ref>[https://www.asbcnet.org/publications/journal/vol/Abstracts/bc1995a22.htm Existence and Development of Natural Microbial Populations in Wooden Storage Vats Used for Alcoholic Cider Maturation. C. H. Swaffield and J. A. Scott. 1995. DOI: 10.1094/ASBCJ-53-0117.]</ref>. Additionally, some strains of ''Lactobacillus'' can survive higher temperatures than ''Brettanomyces'' can; see [[Lactobacillus#Tolerance_of_Extreme_Temperature|''Lactobacillus'']] for more information. Other yeast species may also be more resistant to heat sanitation in barrels. Specifically, ''Debaryomyces hansenii'', ''Candida parapsilosis'', ''Candida ishiwadae'' have been found to be more resistant to steam treatment in wine barrels than ''B. bruxellensis'' <ref>[https://link.springer.com/article/10.1007/s00217-011-1523-8#citeas Guzzon, R., Widmann, G., Malacarne, M. et al. Survey of the yeast population inside wine barrels and the effects of certain techniques in preventing microbiological spoilage. Eur Food Res Technol 233, 285–291 (2011). https://doi.org/10.1007/s00217-011-1523-8.]</ref>.

''Sulfur Storage Solution Method:'' Barrels can be stored full with a solution of water, potassium metabisulfite, and citric acid. The citric acid is used to lower the pH which is necessary to make the potassium metabisulfite antimicrobial (see [https://grapesandwine.cals.cornell.edu/newsletters/appellation-cornell/2012-newsletters/issue-12/article-contains-sulfites/ this Cornell University blog post]).

''Update:'' The lined out instructions above have sometimes been advised by winemakers, and presumably taken from their instructions <ref>[http://www.juicegrape.com/documents/documentview.ashx?id=412fa046-2de0-4051-9d41-a1ee012cea11 M&M Wine Grape Co. Citric Acid & Sulfite Barrel Preparation. Retrieved 03/06/2016.]</ref>. Jay Goodwin from The Rare Barrel, ; however, reported sulfur off-flavors in beers from using too much potassium metabisulfite in their barrels. The beers needed extended aging for the sulfur to be volatilized off. Eric Salazar from New Belgium Brewing advised that they cut the potassium metabisulfite powder down to 1 ounce per 59 gallon barrel (~0.017 ounces per gallon/~0.127 grams per liter) <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1648119741882900/?comment_id=1648160011878873&reply_comment_id=1648559265172281&comment_tracking=%7B%22tn%22%3A%22R0%22%7D Mike Makris. Milk The Funk Facebook group. 04/12/2017.]</ref>, and to check the barrel once a month and change the storage solution once a month if needed <ref>[http://www.thebrewingnetwork.com/the-sour-hour-episode-28/ The Sour Hour Episode 28 (~49 minutes in). Jay Goodwin from The Rare Barrel. 02/17/2016]</ref><ref name="makris" />. The amount of citric acid is the same: 0.5 lb per 59 gallon barrel (1 gram per liter/0.13 ounces per gallon) <ref name="makris">Private correspondence with Mike Makris from The Rare Barrel by Dan Pixley when asked to clarify the amounts that Eric from NBB recommended. 03/06/2016.</ref>. Before using a barrel holding this sort of storage solution, the barrel should be intensely sprayed and rinsed (not just filled up with hot water and dumped). Steaming the barrel before hand can also reduce microbial populations (see [[Barrel#Sanitizing|Sanitizing Barrels]] above).

''Ozone Method: <ref>[http://mcclainozone.com/brewery-ozone-sanitation/ Ozone sanitation for barrels]</ref> [need to expand]''

* [https://abeerdiary.wordpress.com/2016/09/26/my-diy-barrel-steamer/ DIY barrel steamer from Ethan Tripp; "A Beer Diary".]

Pyramid stacking is a semi-permanent structure of barrels that are stacked upon each other with wood wedges to secure their location. Barrels are first stacked empty, and once filled they do not move. The head is often drilled with a 15/16th drill bit near the bottom of the barrel when lying horizontally, and plugged with a standard champagne cork. To empty the barrel, the champagne cork is removed and a barrel tap is inserted into the hole to rack the beer. This method requires less space horizontally than using barrel racks and avoids the cost of barrel racks, however, if a barrel on a bottom row needs to be removed then all of the barrels above it also need to be emptied and moved. Mobility of barrels is therefore sacrificed for space and cheaper cost. Another benefit of pyramid stacking is that a [https://www.facebook.com/photo.php?fbid=10101163850672808 forklift] is not required. See also [https://www.facebook.com/groups/MilkTheFunk/permalink/1932486870112851/?comment_id=1932686786759526&reply_comment_id=1932706406757564&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Andrew Zinn's list of benefits to pyramid stacking].

Barrel Tap Manufacturers:* [httphttps://www.funkfactorygeuzeriaglaciertanks.com/2015barrel-tap-21mpb-g150-1.75hole.html? Glacier Threaded Barrel Tap | Tri Clamp 1.5 in. for 1.75 in. Bung Hole - SS304.]* [http://04www.gwkent.com/pyramidoak-cask-fitting-techniqueadapter-to1-stacking1-barrels2in-tc.htmlGW Kent Oak cask Fitting Adapter.] Also see [https://www.facebook.com/groups/MilkTheFunk/permalink/1326714200690124/?utm_sourcecomment_id=feedburner1327206697307541&utm_mediumcomment_tracking=email&utm_campaign=Feed%7B%22tn%22%3A+FunkFactoryBrewing+%28Funk+Factory+Brewing22R1%29 22%7D this tip from Jeff Porn on fittings].* <span style="text-decoration: line-through;">Jeff Porn group buy organized on MTF from a Colorado manufacturer.</span> (No longer available) Informational MTF posts:* [http://funkfactorybrewing.blogspot.com/2015/04/ Funk Factory Geuzeria - Pyramid Stacking Technique for Barrels]

* [http://wwwfunkfactorybrewing.funkfactorygeuzeriablogspot.com/2012_09_01_archive2012/09/barrel-tap.html Funk Factory Geuzeria - Barrel Tap.]* [http://www.gwkent.com/oak-cask-fitting-adapter-1-1-2in-tc.html GW Kent Oak cask Fitting Adapter.] Also see [https://www.facebook.com/groups/MilkTheFunk/permalink/13267142006901243042914999070027/?comment_id=1327206697307541&comment_tracking=%7B%22tn%22%3A%22R1%22%7D this tip from Jeff Porn on fittingsGlacier versus GW Kent barrel tap discussion.].

* [https://store.tcwequipment.com/products/tcw-suction-racking-wands TCW barrel racking wand that fits in-between pyramid stacked barrels.] <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1981200911908113/?comment_id=1981201901908014&reply_comment_id=1981513658543505&comment_tracking=%7B%22tn%22%3A%22R%22%7D Tristan Stewart. MIlk Milk The Funk Facebook thread on Tristan's brewery and racking wand for pyramid stacked barrels. 02/07/2018.]</ref>* [https://www.facebook.com/BokkereyderBokke29/posts/668103123521646?comment_id=668251680173457&reply_comment_id=669037893428169&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Bokke (formerly Bokkereyder ) reported that a stability engineer quoted that 7 levels of barrels in a pyramid stack using BokkereyderBokke's structure was safe.]

* [httphttps://www.thevintnervault.com/product/4386/Solidbungs-rubber-stoppers-standard-silicone-bung-js-Dualsolid-Fermentationbng-Bung.html 1005/ Solid Dual Fermentation Bung (The Vintner's Vault).]* [httphttps://www.thevintnervault.com/product/923/Dualbungs-rubber-stoppers-dual-fermentation-bung-Fermentationbng-Bung.html 1004/ Duel Fermentation Bung (The Vintner's Vault).]* [httphttps://barrelbuilders.com/storeshop-2/fermrite-fermentation-bung/?model_number=BF04 Ferm-Rite Silicone Bungs (Barrel Builders).]

* [httphttps://www.keystonehomebrewvintable.com/wp-contentcollections/uploads/2017/06/KFS-Offer-Barrel-Accessories.pdf bungs Keystone Homebrew Supply (full-size barrel ventilated bungs and cooperage equipment.]* [httphttps://www.boswellcompany.com/bungtoolsbungs Boswell Company bungs.]* [https://midwestbarrelco.com/collections/ferm-rite-fermentationbarrel-bungs/ Ferm-Rite Midwest Barrel Co. (Boswell Companymultiple sizes).]

* [http://wwwfunkfactorybrewing.funkfactorygeuzeriablogspot.com/2012/02/paraffin-waxing-barrel.html Paraffin waxing a barrel, Funk Factory blog article.]

* [http://www.mcmaster.com/#97990a102/=109otq7 McMaster-Carr Type 316 Stainless Steel Nail; 4D Size, 1-1/2" Length, Approximately 200 Pieces/Pack] and the [http://www.mcmaster.com/#97990a104/=109ouzq 6D Size, 2" Length for a backup if the hole gets bigger (as per Vinnie).] Similar nails are also available on [https://www.amazon.com/Simpson-Strong-S4CN1-1-Pound-Stainless/dp/B007RW6X3M Amazon], [https://www.atlanticbrewsupply.com/Stainless-Steel-Nail-for-Barrels-aka-Vinnie-Nail_p_2467.html Atlantic Brewing Supply (smaller amounts)], and [https://www.manasquanfasteners.com/category/nails-hand-drive Manasquan Fasteners].

* [httphttps://eastcoastwoodbarrelseastcoastbarrels.com/ East Coast Wood Barrels.]

* [https://www.facebooknortheastbarrelcompany.com/northeastbarrelcompany Northeast Barrel Company (east coast and west coast locations).]