Changes

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.