I am hoping somebody can give me info on the cons or lack thereof (I hope) of pitching appropriate quantity of properly stored yeast that have exhausted their energy reserves (glycogen and trehalose) besides longer lag times and thus increased chance of infection (which I am not worried about).
When I can I harvest yeast from the primary to use for the next batch but due to time lapses I usually feed the yeast between batches; accordingly fermentation takes off in less than six hours. For the first time I pitched harvested yeast after six days in the fridge and the lag time was approx 18 hours. Since everything else was equal (pitching rate, oxygenation, wort temp) I assume the increased lag time is due a lack of consumed energy reserves / state of dormancy.
So, other than the yeast taking longer to ‘wake up’ and get kicking, and thus the increased chance of undesired microbes propagating, does a longer lag time hurt anything? The only thing I can imagine might be an issue is increased esters, but not sure why.
You are probably right but 18 hours is not a really long lag time to me. Did you use a yeast calculator like Mr Malty? After 6 days I would consider the harvested yeast to be pretty fresh, unless harvested from a primary that had sat for a long time…
Yeah I used mr. malty repitching from slurry and its estimated viability calculation, which was 85%, but I do feel as if those viability calculators tend to exaggerate the rate of cell death.
Interesting…I just pitched a pint Lager slurry(4/24/15) that was harvested 1/15/15 and stored in the fridge since. I had active fermentation in 6hrs at 53f.
Wow, that is pretty crazy! What size batch was it pitched into? I have never trusted to let my stored yeast sit that long without first making a starter from it to get it going again prior to pitching.
How many days elapsed between pitching and cropping? Longer lag times are usually the result of depleted ergosterol and UFA reserves. Do you aerate a culture when you feed it?