Changes

There is no hard and fast rule for when to package based on final gravity because the gravity of the finished beer will depend on recipe, process, and microbes present among other factors. Generally, lower final gravities are safer because they constrain the extent to which the beer can continue to ferment and generate extra CO2 CO² in the package. But rather than looking for a specific number, pay more attention to the stability of the gravity. Jay from the Rare Barrel recommends waiting at the final gravity for 2-3 months in mixed fermentation beers to ensure that this gravity is the actual final gravity <ref name='Sour Hour episode 6'>[http://www.thebrewingnetwork.com/the-sour-hour-episode-6/ The Sour Hour episode 6 Listener Q&A]</ref> (~38 minutes in). If the gravity is stable over a long time scale (weeks to months, depending again on factors such as the recipe, process, and microbes present), then the beer is probably done. If you are unsure then give the beer a bit longer and monitor final gravity. Keep in mind that sampling sour beer too often can lead to too much oxygen exposure, and care should be taken not not sample too much and purge with CO2; see [[Mixed_Fermentation#Aging|Mixed Fermentation]] for more information. Each gravity point (.001) of continued fermentation yields roughly 1/2 volume of CO2 (each degree Plato yields 2 volumes of CO2) <ref>[http://braukaiser.com/wiki/index.php/Accurately_Calculating_Sugar_Additions_for_Carbonation#Remaining_or_Residual_Extract "Accurately Calculating Sugar Additions for Carbonation." Kai Troester. Braukaiser.com. Retrieved 08/07/2016.]</ref>. Sometimes beer samples will contain high amounts of carbonation due to gradual fermentation from ''Brettanomyces'' (in other cases when the beer has aged for a very long time, there may be much less residual carbonation than normal). Therefore, it is best practice to degas the sample by pouring it through a membrane filter such as a coffee filter in order to obtain an accurate gravity reading <ref>[http://methods.asbcnet.org/summaries/degassingmatrix.aspx "Recommended Beer Degassing Methods and Alternatives Matrix". ASBC Methods of Analysis. Retrieved 03/04/2020.]</ref>.

With continual batches of beer using the same grist and strains of microbes, a stable final gravity can become more easily predicted by the brewer and waiting for a stable final gravity may no longer be necessary once a known stable final gravity is achieved (note that a change in the strains being used or the grist could result in a different stable final gravity). For example, see the [[Brettanomyces and Saccharomyces Co-fermentation#Dosing_Clean_Beer_with_Brettanomyces_At_Bottling|Brettanomyces and Saccharomyces Co-fermentation]] page for techniques for inoculating ''Brettanomyces'' at bottling time into a clean beer that was fermented with just ''S. cerevisiae'', see the [[Brettanomyces and Saccharomyces Co-fermentation#Dosing_Clean_Beer_with_Brettanomyces_At_Bottling|Brettanomyces and Saccharomyces Co-fermentation]] page. For suggested equipment for reading gravity from small samples, see [[Packaging#Density_Meters|Density Meters]].

Commercial producers and MTFers have had success re-yeasting with their mixed culture, wine yeast, and champagne yeast. The specific yeast you choose is up to you, and we recommend that you try a couple different yeasts out to find the one you prefer (MTFers have reported success with Lalvin EC-1118 Champagne, Red Star Premier Cuvée, Red Star Pasteur Blanc, Danstar CBC-1, Fermentis T-58, Scott Laboratories DV10 wine yeast, and fresh cultures of ''Brettanomyces'' <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1477763322251877/ Conversation on MTF regarding bottle conditioning yeast. 11/21/2016.]</ref>). When re-yeasting at bottling for a beer that has some residual gravity (a higher than 0 plato or specific gravity), take care not to use a highly attenuative yeast that could over-attenuate the beer in the package. For example, adding ''Brettanomyces'' or a diastatic strain of ''Saccharomyces cerevisiae'' var. ''diastaticus'' strain at bottling to a beer that has some residual sugars could result in over-carbonation in the bottle <ref name='Sour Hour episode 6'/> (~41 minutes in). If the beer has a significantly high finishing gravity, then re-yeasting with a yeast that beer has already seen should eliminate the possibility of continued attenuation as long as the beer is already at final gravity. Using rehydrated dry yeast has been shown to be more reliable than both slurries and even freshly propagated yeast probably due to their rich sterol reserves (this excludes freshly propagated yeast using acid shock starters - see below) <ref>[https://www.researchgate.net/publication/293337388_Effect_of_pitching_yeast_preparation_on_the_refermentation_of_beer_in_bottles an Landschoot, A., Vanbeneden, N., Vanderputten, D. and Derdelinckx, G. (2004). Effect of pitching yeast preparation on the refermentation of beer in bottles. Cerevisia 29:140-147.]</ref><ref>Van den Berg, S., Demeyere, K. and Van Landschoot, A. (2001). The use of dried yeast for the bottle refermentation of beer. Cerevisia 26:102-108.</ref>. Brewers who are having difficulty carbonating sour beer or need to ensure that the beer will carbonate properly should grow their yeast first in an [[Packaging#Acid_Shock_Starters|Acid Shock Starter]]. This will acclimate the yeast to the harsh conditions of the sour beer, and has shown to be more effective for ensuring bottle carbonation <ref>[http://www.sciencedirect.com/science/article/pii/S0740002016301605 Terminal acidic shock inhibits sour beer bottle conditioning by Saccharomyces cerevisiae. Cody M. Rogers, Devon Veatch, Adam Covey, Caleb Staton, Matthew L. Bochman. 2016.]</ref>. Not all sour beers will need the priming yeast to be acclimated, but sour beers with darker malts, acidic fruits, and high ABV (8%+) might require this step. See [[Packaging#Acid_Shock_Starters|Acid Shock Starters]] below, and [[Saccharomyces#Fermentation_Under_Low_pH_Conditions|fermenting in low pH conditions]] for more information on the science behind this technique.

Below are several ''acid shock starter'' techniques for acclimating yeast to the harsh conditions of acidic wort or beer, including mixed fermentation sour beers and kettle sour beers. See [[Saccharomyces#Fermentation_Under_Low_pH_Conditions|fermenting ''Saccharomyces'' under low pH conditions]] for more information on the science behind this.

* See also [https://web.archive.org/web/20211023133240/https://www.therarebarrel.com/index.cfm?method=blog.blogDrilldown&blogEntryID=F8F5CB68-B1C7-9CB1-ACBD-546329AE621D&originalMarketingURL=blog/Terminal-Acidic-Shock-and-Sour-Ale-Bottle-Conditioning The Rare Barrel's acid shock treatment].* See also [https://www.facebook.com/groups/MilkTheFunk/permalink/4429403613754485 this MTF thread] for updates on acclimation methods and reported experiences.

# Take a "pinch" of rehydrated dried yeast, and pitch 150,000 cells/mL into 100 mL of '''YPD + Go-Ferm Media'''. Grow for ~24 hours at 86°F (30°C ) with shaking.# Transfer the starter into 100 mL of '''Adaption Media 1'''. Grow for ~24 hours at 86°F (30°C ) without shaking.# Transfer the starter into '''Adaption Media 2''' (whatever volume is needed for batch size). Grow for ~24 hours at 86°F (30°C ) without shaking.

: ''This method has not yet been validated as far as producing the correct pitching rate for re-yeasting, which is suggested to be 1 million cells per mL of beer.''

# Measure 50 mL of the sour beer that is going to be carbonated, and combine it with 100 mL of apple juice with no preservatives (or use DME if using a beer yeast strain) and a pinch of [http://www.scottlab.com/product-103.aspx Go-Ferm] in a saucepan.# Heat pasteurize the sour beer, apple juice (make sure there are no preservatives in the apple juice), and [http://www.scottlab.com/product-103.aspx Go-Ferm] mixture on the stove at 140°F 160°F for 10 minutes. # Cool the sour beer and apple juice mixture to around 70-85°F86°F (30°C). Pitch into an Erlenmeyer flask, along with the re-hydrated wine yeast.# Grow for ~24 hours without shakingat around 86°F (30°C) *.

# Heat pasteurize the sour beer, apple juice (make sure there are no preservatives in the apple juice), and [http://www.scottlab.com/product-103.aspx Go-Ferm] mixture on the stove at 140°F 160°F for 10 minutes. # Cool the sour beer and apple juice mixture to around 70-85°F86°F (30°C). Top up the Erlenmeyer flask with the yeast starter in it with this fresh mixture.# Grow for ~24 hours without shakingat around 86°F (30°C) *.

# Add After the 24 hours of growth is finished for the final step, add ~200 mL of the starter per 20 liters of beer (stir the starter before adding into the beer; this does not account for the sugar that needs to be added to achieve carbonation because the apple juice should be fully fermented at this stage). <nowiki>*</nowiki> If a fermentation temperature of around 86°F (30°C)cannot be maintained and the temperature falls during the 24 hour growth period, allow the final step to ferment for 48 hours before adding it to the beer just to make sure the apple juice is fully fermented.

Alternatively, beer can be kegged and force carbonated, and like any other beer. Beer can be then bottle /crowler/can filled from the keg using a beer gun or some other device. Anecdotes from some brewers have reported a higher chance of [[Tetrahydropyridine|THP]] production when force carbonating some mixed fermentation beers (see the [[Tetrahydropyridine|THP]] page for more information). See [[Packaging#Package_and_closure_types|Package Types]] below for more information on kegging in general.

# For 7 barrels/217 gallons of beer, re-hydrate 250 grams dissolve the 12 pounds of cane sugar (0.88 ounces of sugar per 1 gallon of yeast beer) in ~3.5 gallons of 108-110°F water and then dissolve . After the 12 pounds sugar dissolves, add 250 grams of cane yeast to the sugar in the water with the re-hydrating yeast (1.15 grams of yeast and 0.885 oz of sucrose dissolved in 2 fl oz of water per gallon of beer, or 6.628 grams of sucrose per liter of beer). The amount of yeast is less important than the amount of sugar <ref name="Gus_Sylvester_Method"></ref>)<ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1917477671613771/?comment_id=1917618818266323&reply_comment_id=1917621641599374&comment_tracking=%7B%22tn%22%3A%22R2%22%7D Bob Sylvester on rehydrating yeast and sugar together. Milk The Funk Facebook group. 12/13/2017.]</ref>. I do this first and let it bloom while I transfer the beer from the fermenter to my kettle. Takes about 20 -30 minutes. By this time the yeast is about to crawl out of the bucket. ''Editor's note: many homebrewers have had success carbonating sour beer with only 1-2 grams of wine yeast for 5 gallons of beer.''# Add the yeast /sugar slurry just before the transfer is finished as this will help incorporate the slurry. Carbonation happens the same day as packaging if done correctly.

# Sanke keg conditioning uses the same exact process but back the sugar down to 8 pounds (0.59 ounces of sucrose per gallon of beer or 4.4186 grams of sucrose per liter of beer) and keep the yeast at 250 grams. Fill the keg to the shoulder where the side and the lid meet (too much headspace leads to too high of a carbonation level). One recommendation for getting the right headspace is to lift one side of the keg onto a 2x4 wood block and fill it while the keg is leaning at an angle (this method works best for half barrel kegs; smaller kegs might tip over) <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2337168479644686/?comment_id=2337190276309173&comment_tracking=%7B%22tn%22%3A%22R3%22%7D Bob Sylvester and Allen Stone. Milk The Funk Facebook group thread about keg conditioning and fill level. 10/26/2018.]</ref>. ## Note: For a discussion on why or why not the dosage of priming sugar for kegs should be lower than for bottles, see [https://www.facebook.com/groups/MilkTheFunk/permalink/4607537139274464/?comment_id=4607551389273039&reply_comment_id=4607649122596599 this thread].

Oxygen is the enemy of finished beer, and most producers of standard beers invest a lot of time and money to reduce into reducing oxygen exposure in their finished beer (referred to as "dissolved oxygen", for oxygen in the beer or "total packaged oxygen"for total oxygen in the beer plus additional oxygen in the headspace of the package). Excessive oxygen exposure can negatively impact the beer either permanently through the formation of acetic acid and/or ethyl acetate, temporarily by increasing [[tetrahydropyridine]] (THP) formation, or through the [[Aging_and_Storage#General_Effects_of_Oxidation|oxidation of various compounds]]. For mixed fermentation beers where fresh bottling yeast is added, this may not be as significant of a concern, depending on how much oxygen is allowed to enter the packaging. These beers, especially barrel aged versions, generally have more oxygen exposure during fermentation and aging, and this contributes to the characteristics of the beer. ''Brettanomyces'' is known as an "oxygen scavenger", which helps to prevent oxidative reactions in the bottle over time (see [[Aging and Storage]]). Fresh bottle conditioning yeast can help prevent acetic acid and THP production by consuming the oxygen in non-purged bottles before it can have an effect on the mixed culture. Even without fresh bottling yeast, some brewers achieve good results without purging bottles before filling (for example, lambic producers and blenders), although this might be dependent on whether the strains present in the beer are big THP producers or if the brewer has limited time to store bottles long enough for the THP to age out. Others do take care to avoid oxygen exposure in the packaging process and report that purging bottles with CO₂ helps prevent THP formation. Due to these many variables, there is no easy answer in terms of whether it is better to carefully CO₂ purge as is standard practice for clean beers. CO₂ purging can require more expensive equipment, as well as require more time to package. Based on the characteristics of the microbes being used, experience, equipment, process, and preferences, the brewer can determine how much limiting O² exposure during packaging is necessary. The safest route is to treat them as you would a normal beer and take care to avoid O² where this is possible or affordable, though the experience of some will say that this extra work and cost is might not be completely necessarylike it is for clean beers.

See also;:* [https://www.facebook.com/groups/MilkTheFunk/permalink/2375853352442865/ MTF thread on whether or not to purge the top of the bottling machine with CO₂.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/2282287018466166/ Justin Amaral's can conditioning project with DO tracking for canned conditioned beers on MTF.]* [https://www.facebook.com/groups/MilkTheFunk/posts/6845568052138017/ MTF thread on the science available regarding the idea that yeast can scavenge oxygen after packaging.]

MBAA podcasts:* [https://www.facebookmasterbrewerspodcast.com/groups055 Episode 50 - TPO with Kevin Sudderth & Mike Feldman from Hach.]* [https:/MilkTheFunk/permalinkwww.masterbrewerspodcast.com/2375853352442865150 Episode 150 - TPO Gone Wild? Managing Oxygen Ingress on Smaller Scale Canning Lines.]* [https://www.masterbrewerspodcast.com/ MTF thread on whether or not to purge the top of the bottling machine 178 Episode 178 - Friends Don't Let Friends Drink Oxidized Beer (minimizing oxygen in brite tanks and packaging with CO₂guest Audrey Skinner).]

* '''Green glass v Brown glass''' - Some bottle types, especially champagne style bottles, may be more available in green glass compared to brown glass. Green glass does a worse job shielding the beer from UV spectrum light, which can interact with hop compounds to produce 'skunky' or lightstruck flavors and aromas. Many classic Belgian mixed fermentation beers are found in green glass, and some producers in North America seek out green glass over brown glass for their beers <ref>[http://jesterkingbrewery.com/jester-king-in-green-bottles Jester King blog post about green bottles]</ref><ref>[http://www.thebrewingnetwork.com/the-sour-hour-episode-15/ Jester King on the Sour Hour, pt 2]</ref> (~11 minutes in) (also, Bob Sylvester). See also [[Aging_and_Storage#Lightstruck|Lightstruck]].

Usually, only pasteurized sour beer is canned due to the danger of over-carbonating canned beer, however, some brewers have been experimenting with canning mixed fermentation beer and allowing the beer to naturally carbonate in the cans. It is recommended that brewers contact their can supplier to verify that the plastic liners for the cans are rated to handle the pH of sour beer (3-4 pH; kettle soured or otherwise) and to find out the lifespan of the cans. Cans have been found to preserve some hop compounds such as myrcene and caryophyllene better than bottles because bottle caps can strip some of these compounds <ref>[https://onlinelibrary.wiley.com/doi/full/10.1002/jib.667 Kemp, O., Hofmann, S., Braumann, I., Jensen, S., Fenton, A., and Oladokun, O. (2021) Changes in key hop-derived compounds and their impact on perceived dry-hop flavour in beers after storage at cold and ambient temperature. J. Inst. Brew., https://doi.org/10.1002/jib.667.]</ref>.

* [https://www.facebook.com/groups/MilkTheFunk/permalink/2655248284503369/ General MTF tips on canning]. * [https://www.facebook.com/groups/MilkTheFunk/permalink/2705352459492951/ Discussion on the safety of canning mixed fermentation sour beer versus Coke (pH 2.5) and kettle sours, as well as other general canning information.]* See this [https://www.facebook.com/speciationartisanales/videos/125350678350276/ video of Speciation Artisen Ales canning process (conditioning in the can)].** [https://www.facebook.com/groups/MilkTheFunk/permalink/2260040164024185/?comment_id=2260061030688765&reply_comment_id=2260181380676730&comment_tracking=%7B%22tn%22%3A%22R%22%7D Canning tips Mitch Ermatinger gives advice on using cans.]** [https://www.facebook.com/groups/MilkTheFunk/permalink/2705564312805099/ More videos from Mitch Ermatinger on MTFcanning using a GW Kent filler and Oktober seamer.]** [https://www.facebook.com/groups/MilkTheFunk/?post_id=3803228973038622&comment_id=3803870986307754 Mitch's advice on CO₂ levels when can conditioning mixed fermentation sours.]* [https://www.facebook.com/groups/MilkTheFunk/permalink/2282287018466166/ Justin Amaral's can conditioning project with DO tracking for canned conditioned beers on MTF.]* Mobile canning companies that will can mixed fermentation beer:** [https://craftcanning.com/ Craft Canning]* [https://www.facebookmasterbrewerspodcast.com/224 MBAA Podcast Ep 224 "Can Liner Quality & Testing".]* [https://seamschool.com/speciationartisanalesSeam School]* [https://web.archive.org/web/20220110012615/videoshttps:/125350678350276/ Video of Speciation Artisen Ales canning process (conditioning in the can)doubleseam.com/ Double Seam]

* [http://www.shorecontainer.com/750mlamberchampagneflatbottom.aspx Shore Container, 750 mL 26 mm cap bottles.]* [https://www.txbrewing.com/equipment/bottling/bottles.html Texas Brewing: 500/330 mL Green Morning Bottles, 750 mL Green California Style Beer Bottle (crown or cork).]* [https://chicagobrewwerks.com/collections/racking-bottling/bottles-growlers Chicago Brew Werks: 500 mL cork and cage or crown with punt, and various Morning bottles and other Belgian bottle formats.]* Homebrewing.org [http://www.homebrewing.org/Belgian-Beer-Bottles-750-ml-Case-of-12_p_6456Homebrewing.html org; 750 mL cork and cage bottles] and [http://www.homebrewing.org/375ml-Belgian-Bottles-Cork-Finish-12-ct_p_6113.html 375 mL cork and cage bottles.]* [httphttps://www.milkthefunkmorebeer.com/w/index.php?title=Packaging&action=edit&section=17 MoreBeer Amber Champagne/Belgian Style bottles (also has non-punted versions).]* [https://morewinemaking.com MoreWine Champagne bottles.]* [http://mdhb.com/index.php?cPath=21_41_42&osCsid=c5e061b72a Maryland Homebrew: 750 mL Belgian bottles and Champagne Bottles(offers 3 liter magnums).]* [httphttps://www.curdsandwine.com/products/winemaking-supplies-hardware/375-ml-champagne-bottles-case-of-12 Curds and Wine (green champagne).]* [http://www.keystonehomebrew.com/shop/wine/bottling-racking/bottles/wine-bottles-500-ml-champagne-green-case-13.html Keystone Homebrew Supply (green bottles, multiple sizes750 mL).]* [https://www.midwestsupplies.com/homebrewing-equipment/bottling/bottles Midwest Supplies: 375/750 mL Belgian bottles ('''this homebrew store is owned by ABInBev''').]* [http://www.northernbrewer.com/brewing/brewing-equipment/bottling/bottles Northern Brewer: 750 mL and 350 mL, cork and caged, and crown capped Belgian bottles '''(this homebrew store is owned by ABInBev)'''.]* [https://www.baderbrewing.com Bader Beer and Wine Supply - 3 Liter Antique Green Flip-top bottle.]* [https://www.austinhomebrew.com Austin Homebrew Supply.]* [https://brewshop.no Brewshop, Norway: 750 mL and 375 mL Champagne bottles.]

* [http://www.unitedbottles.com/ United Bottles & Packaging(has magnums).]* [https://beer.buyourbottles.com/ Buy Our Bottles.]* [https://www.wineandbeersupply.com Wine and Beer Supply.]* [https://shop.countrymalt.com/supplies-and-cooperage Country Malt Group.]* [https://www.saverglass.com/en/catalog/sparkling-wines Saver Glass (multiple sizes and styles of green glass bottles.]

* [http://www.waterloocontainer.com Waterloo Container.](Also has large formats: 1.5L, 3L, 6L, and 9L, and 375 mL green bottles).

* [https://buyourbottleswww.estal.com/amber-glass-bottles/glass-750ml-belgian-in-cases Buy Our BottlesEstal (large formats).]

* [https://www.croxsons.com/our-products/375ml-champagne-2/ Croxsons champagne bottles (multiple sized green bottles, including 375 mL and 3L - UK).]

* [https://www.pelliconi.com/site/en/crown-corks-29mm/ Pelliconi.]* [https://unitedbottles.com/product/29-mm-crown-cap-bc017 Unitied United Bottles.]

* [https://www.facebook.com/Dominion-Grimm-Inc-259502154148301/ Dominion and Grimm (Canada).]