What are your thoughts, Mark? You seem to indicate that any yeast that can carbonate can consume oxygen, which makes sense to me.
Yeast cells always consume O2
post fermentation if the ethanol level is not high enough to kills the cells off. The main benefit that bottle conditioning brings is that it gives quiescent yeast cells a new carbon source to consume, so they effectively go through a second fermentation cycle, eliminating any O2
pickup. Now, adding O2
to finished beer that contains viable cells and no carbon source other than ethanol results in the yeast cells under a diauxic shift where they can consume ethanol aerobically, reducing ethanol to its precursors (Google "yeast diauxic shift ethanol"). The effect is usually minuscule on carefully handed beer, but the threat from using a secondary fermenter to dry hop has become way overblown amateur brewer dogma. Adding a small amount of priming sugar in a 1 to 2% boiled solution to a secondary or keg will pretty much end the discussion on O2
pickup because it will eliminate diauxic shift to using ethanol as a carbon source while the yeast cells are scrubbing O2
. As a community, we need to reference science before creating dogma. We are creating brewing dogma faster than it can be dispelled. I recommend reading my blog entries entitled "Carbon Credits" (https://www.experimentalbrew.com/blogs/saccharomyces/carbon-credits
) and "Have You Seen Ester?" (https://www.experimentalbrew.com/blogs/saccharomyces/have-you-seen-ester
) to anyone who wants to understand how yeast cells consume carbon and produce metabolic byproducts.