verysupple
Supremely mediocre brewer
- Joined
- 23/9/12
- Messages
- 1,057
- Reaction score
- 268
Hi all,
I think most of us agree with and follow the idea that it's generally better to leave the beer in the fementor for a longer rather than a shorter period of time before packaging (within reason). The idea behind this is that you leave the beer in contact with a larger quantity of yeast so it conditions faster. My question is how much conditioning is a function of yeast activity and how much is other (non yeast) chemical reactions?
I know that after the exponential phase of fermentation that the yeast then metabolise undesirable compounds they produced earlier, such as diacetyl, acetaldehyde etc., but we would all have noted the difference between young beer that still contains high levels of diacetyl etc. and what I call "green beer" which has had time to reduce those compounds but still needs time for the flavours to mellow and round out. So in my mind there are two parts to conditioning - reducing unwanted compounds which takes only a few days and flavour maturation which can take from a few days to weeks.
My gut feeling is that the "mellowing" probably isn't a function of yeast metabolism but chemical reactions between other constituents of the beer. If this is true then the beer can be separated from the bulk of the yeast and packaged earlier without adversely affecting the conditioning process which has obvious positive implications for my production rate, which always seems to lag behind my consuption.
I've had a bit of a search and didn't find a great deal so does anyone have any info/sources regarding this?
PS. I'm not really looking for "Well, I always leave it in the FV for 3 weeks and it works for me." because we already know that works. I'm looking for the science behind beer conditioning.
I think most of us agree with and follow the idea that it's generally better to leave the beer in the fementor for a longer rather than a shorter period of time before packaging (within reason). The idea behind this is that you leave the beer in contact with a larger quantity of yeast so it conditions faster. My question is how much conditioning is a function of yeast activity and how much is other (non yeast) chemical reactions?
I know that after the exponential phase of fermentation that the yeast then metabolise undesirable compounds they produced earlier, such as diacetyl, acetaldehyde etc., but we would all have noted the difference between young beer that still contains high levels of diacetyl etc. and what I call "green beer" which has had time to reduce those compounds but still needs time for the flavours to mellow and round out. So in my mind there are two parts to conditioning - reducing unwanted compounds which takes only a few days and flavour maturation which can take from a few days to weeks.
My gut feeling is that the "mellowing" probably isn't a function of yeast metabolism but chemical reactions between other constituents of the beer. If this is true then the beer can be separated from the bulk of the yeast and packaged earlier without adversely affecting the conditioning process which has obvious positive implications for my production rate, which always seems to lag behind my consuption.
I've had a bit of a search and didn't find a great deal so does anyone have any info/sources regarding this?
PS. I'm not really looking for "Well, I always leave it in the FV for 3 weeks and it works for me." because we already know that works. I'm looking for the science behind beer conditioning.