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 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 recipe, process , and microbes present), then the beers beer is probably done. If you are unsure then give the beer a bit longer and monitor final gravity. 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>.

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]].

Beer with ''Brettanomyces'' and bacteria, as well as certain ''Saccharomyces'' strains, will take longer to clear than other beers. Generally , time can take care of most of the clarification in mixed fermentation beers with long aging times. Faster turnaround beers or kettle sours may not clarify by time alone. The level of clarity you are looking for before packaging will depend on your preferences and the beer you are making. Beer can be packaged without good clarity and they will continue to settle out in the bottle, but note that beers with high carbonation levels may kick the sediment back into suspension, which may or may not be what you want in your beer.

If your beer is at final gravity, you can prime it as you would any normal beer based on the amount carbonation you want. In order to properly prime your beer, you will need to know your residual CO2 in solution. This can be determined from temperature and good priming sugar calculators take this into account. For aged beers, especially beers which have been aged in barrels or a similar porous vessel, the starting CO2 may be lower than the numbers produced from these calculators due to off gassing while the beer is aging. We recommend using [http://jeffreycrane.blogspot.com/2015/06/blending-calculator-ph-abv-and.html Jeff Crane's "Blending Calculator" (in progressextension of Michael Tonsmeire's "Blending Calculator")] for priming calculations with aged beer.

If your beer is at final gravity, you can prime it as you would any normal beer based on the amount carbonation you want. In order to properly prime your beer you will need to know your residual CO2 in solution. This can be determined from temperature and good priming sugar calculators take this into account. For aged beers, especially beers which have been aged in barrels or a similar porous vessel, the starting CO2 may be lower than the numbers produced from these calculators due to off gassing while the beer is aging. Tomme Arthur from The Lost Abbey reports that the starting values he sees in barrel aged beers range from 0.2-0.6 volumes of CO2<ref name='Tomme on the Sour Hour'>[http://www.thebrewingnetwork.com/the-sour-hour-the-lost-abbey/ Tomme Arthur from the Lost Abbey on the Sour Hour]</ref> (~51 minutes in). Brewers may choose to partially force carbonate their beers to know the starting CO2 exactly as well as limit the CO2 required from bottle conditioning. The Lost Abbey carbonates to 1.5 volumes of CO2 before priming and bottle conditioning for the remaining carbonation<ref name='Tomme on the Sour Hour'/> (~52 minutes in). Alternatively, a product used in measuring residual CO2 for champagne called a [https://www.reddit.com/r/TheBrewery/comments/6ba8i8/using_a_carbodoseur_to_figure_out_co2_in_solution/ Carbodoseur] can be used to estimate residual CO2 after long aging. See [https://www.facebook.com/groups/MilkTheFunk/search/?query=carbodoseur these MTF threads] on experiences using the Carbodoseur and the [http://www.allafrance.com/notices_pdf/99200-va_FR.pdf Carbodoseur calibration table]. If no effort is made to determine residual CO2, 0.4 has been quoted as a good estimation for aged beer <ref>[https://books.google.com/books?id=l5UIBAAAQBAJ&pg=PA271&lpg=PA271&dq=michael+tonsmeire+residual+co2&source=bl&ots=IQm2_NOAYC&sig=PuhumzttcB_qQHLmNzzGcnmIzDg&hl=en&sa=X&ved=0ahUKEwi_49e-tKDUAhUH6GMKHVBqDj4Q6AEIPzAE#v=onepage&q=michael%20tonsmeire%20residual%20co2&f=false Tonsmeire, Michael. American Sour Beer: Innovative Techniques for Mixed Fermentations. Brewers Publications. 06/15/2014. ISBN-13:9781938469138. Pg 271.]</ref>.

If your beer is not at final gravity, but you have a good idea of where it will finish, then you can prime taking into account remaining gravity points----- to do. See [http://jeffreycrane.blogspot.com/2015/06/blending-calculator-ph-abv-and.html Jeff Crane's "Blending Calculator" (extension of Michael Tonsmeire's "Blending Calculator")[Packaging#Final_Gravity|Final Gravity]] for a re-yeasting and priming calculatormore information.

# For 7 barrels/217 gallons of beer, re-hydrate 250 grams of yeast in 3.5 gallons of 108-110°F water with and then dissolve the 12 pounds of cane sugar dissolved at 108°F in the water with the re-hydrating yeast (0.87 grams of yeast and 1.13 oz of sucrose dissolved in 2 fl oz of water per gallon 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 minutes. By this time the yeast is about to crawl out of the bucket.

Oxygen is the enemy of finished beer, and most producers of standard beers invest a lot of time and money to reduce oxygen exposure in their finished beer(referred to as "dissolved oxygen", or "total packaged oxygen"). Excessive oxygen exposure can negatively impact the beer either permanently through the formation of acetic acid and/or ethyl acetate, or temporarily by increasing [[tetrahydropyridine]] (THP) formation. For mixed fermentation/sour/funky beerswhere fresh bottling yeast is added, this may not be as significant of a concern. These beers, especially barrel aged versions, generally have more oxygen exposure during fermentation and aging , and this contributes to the characteristics of the beer. Some ''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), and others 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 processand report that purging bottles with CO² helps prevent THP formation. There Due to these many variables, there is no definite easy answer in terms of whether it is better to carefully CO2 CO² purge as is recommended in more normal standard practice for clean beers or if the yeasts present in mixed-fermentation beers are better able to quickly scavenge O2 before it . CO² purging can damage the beerrequire more expensive equipment, though excessive oxygen exposure can hurt your beer (either permanently through formation of acetic acid and/or ethyl acetate, or temporarily by influencing [[tetrahydropyridine]] (THP)as well as require more time to package. Based on your the characteristics of the microbes being used, experience, equipment, process, and preferences, you the brewer can determine how much to limit O2 limiting O² exposure in your beersduring packaging is necessary. The safest route is to treat them as you would a normal beer and take care to avoid O2O² where this is possible or affordable, though the experience of some will say that this extra work and cost is not completely necessary.  If force carbonating the beer instead of bottle conditioning with fresh yeast, or if bottle conditioning without adding fresh yeast, it might be best practice to purge bottles and kegs with CO² in order to limit the production of both acetic acid and THP. Again, experience should drive this decision one way or the other.