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 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 take 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>.