PNB Slow Fermentation
It's now six days since I started the primary fermentation of the PNB. I was expecting to rack to the secondary around about now, but I'm not going to yet.
This seems to be a fairly slow fermentation. It took off quickly enough - the yeast starter must have done its work. About 48 hours in, the bubble rate was at about its peak - about 3s per bubble. It has gradually tailed off and is now at 16s per bubble. I think this is still somewhat active, and I think this is backed up by the fact that there is still quite active small-bubbling activity on the surface.
The krausen probably never exceeded 1cm, and has now almost completely subsided, apart from a fine covering of perhaps 1mm dia. bubbles.
Why the slow fermentation? Well, at one point I thought it might have stuck, but I don't think this is the case. The temperature has been a little up and down, between about 62 and 68 degF. I just fully opened the air vent in the bathromm, which will hopefully boost the temp by a few degrees. Other reasons for slow fermentation are probably poor aeration, and attributes of the wort. The wort was made entirely from 12-year old extract, which I guess has undergone some maillard reaction. The yeast probably have to work harder on it. I think the yeast are healthy enough though.
I'll probably leave it until the small bubbles on the surface have cleared, and we have more than 60s between bubbles. At which point I'll measure the SG, and probably rack to the secondary.
This seems to be a fairly slow fermentation. It took off quickly enough - the yeast starter must have done its work. About 48 hours in, the bubble rate was at about its peak - about 3s per bubble. It has gradually tailed off and is now at 16s per bubble. I think this is still somewhat active, and I think this is backed up by the fact that there is still quite active small-bubbling activity on the surface.
The krausen probably never exceeded 1cm, and has now almost completely subsided, apart from a fine covering of perhaps 1mm dia. bubbles.
Why the slow fermentation? Well, at one point I thought it might have stuck, but I don't think this is the case. The temperature has been a little up and down, between about 62 and 68 degF. I just fully opened the air vent in the bathromm, which will hopefully boost the temp by a few degrees. Other reasons for slow fermentation are probably poor aeration, and attributes of the wort. The wort was made entirely from 12-year old extract, which I guess has undergone some maillard reaction. The yeast probably have to work harder on it. I think the yeast are healthy enough though.
I'll probably leave it until the small bubbles on the surface have cleared, and we have more than 60s between bubbles. At which point I'll measure the SG, and probably rack to the secondary.
posted by number9 at 5:11 PM
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