I made 5 gal of a 1.050 beer using Wyeast's 3787 Trappist High Gravity. It turned out great (I love this strain) but I was mostly making it as a big yeast starter for a barley wine I want to make. Last weekend, I racked off all but about a half inch of the beer above the yeast cake, intending to brew the next day. However, life intervened and I didn't get to it. It's been sitting in my basement with the airlock still on it, at about 60 degrees for a week.
So, a week later, my question is whether this yeast cake can still be used. My worries are that it may have:
1. Lost viability over the week. I've found other threads stating that unwashed/unrefrigerated yeast loses 25% viability in a week.
2. Autolysis flavors- since removing the bulk of the liquid on this cake, has the resulting smaller amount become concentrated with off flavors from the decomposing yeast that would transmit to the new beer?
3. Oxygenation of the beer. With no fermentation going on, there has been no blanket of CO2 over the top of this beer for a week. Added to that, the surface area at the bottom of the carboy is much larger than at the tapered neck up at the top. I was careful to replace the airlock as soon as I was done transferring but doubtless the "empty" space has been filled with oxygen this week rather than CO2.
4. Possible contamination from the racking cane/opening the carboy. No matter how sanitary we are (I use a stainless racking cane and star san), there are doubtless still some bacteria introduced when the cane is placed in the beer. This isn't a big deal on a normal basis but after a week, what might have reproduced in my small liquid sample? Can I count on the inside of my carboy still being "sterile" even though I opened the airlock and immersed a (sterilized) racking cane?
So, a week later, my question is whether this yeast cake can still be used. My worries are that it may have:
1. Lost viability over the week. I've found other threads stating that unwashed/unrefrigerated yeast loses 25% viability in a week.
2. Autolysis flavors- since removing the bulk of the liquid on this cake, has the resulting smaller amount become concentrated with off flavors from the decomposing yeast that would transmit to the new beer?
3. Oxygenation of the beer. With no fermentation going on, there has been no blanket of CO2 over the top of this beer for a week. Added to that, the surface area at the bottom of the carboy is much larger than at the tapered neck up at the top. I was careful to replace the airlock as soon as I was done transferring but doubtless the "empty" space has been filled with oxygen this week rather than CO2.
4. Possible contamination from the racking cane/opening the carboy. No matter how sanitary we are (I use a stainless racking cane and star san), there are doubtless still some bacteria introduced when the cane is placed in the beer. This isn't a big deal on a normal basis but after a week, what might have reproduced in my small liquid sample? Can I count on the inside of my carboy still being "sterile" even though I opened the airlock and immersed a (sterilized) racking cane?
