I know that the "to decant or not to decant" topic has been discussed ad nauseam on here. I'm wondering if there are any published studies (from Wyeast, WL or any other source) that look into viability (i.e. number of viable yeast cells) of decanted yeast starters vs starters that have not been cold-crashed and decanted? Seems logical that cold-crashing, decanting and then leaving yeast cake on "no food" after decanting (to bring back to room temperature before pitching) would have an effect on healthy yeast cell count, but how much exactly? Is there any published info from reliable sources on this?
I am not aware of any studies concerning the viability of decanted vs. non-decanted starters. Another consideration is that even if you cold crash there will still be some yeast cells in the starter beer that you are decanting. The vast majority of the yeast cells will be in the slurry at the bottom of the starter vessel but there will still be some yeast cells in the starter beer. Cheers!
I don't decant before brew day either. I usually decant about 2 hours before pitching, to allow for the yeast cake to warm to pitching temperature.
Gotcha, I thought maybe the way you said it that you decanted on a different day than you brewed and put it back in the fridge.
Exactly, you lose yeast cells during the decanting. You also stress the yeast by cold-crashing, then returning to pitching temperature. And you're also stressing the yeast cells by leaving them on "no food" for a few hours from the time you decant to the time you pitch. All those things must have some negative impact on the starter's viability compared to pitching a starter that's at high krausen without decanting. I'd love to know how much of an impact it has.
“All those things must have some negative impact on the starter's viability compared to pitching a starter that's at high krausen without decanting.” That sounds like a reasonable argument to me. Unfortunately I am not aware of any scientific studies which quantify this. Cheers!
I have only done this a few times now, but works great. Take out of fridge, decant, add about a cup of fresh wort to the flask from the last runnings of your mash (boiled and chilled, of course), then put back on the stir plate, during the remainder of the boil and chill for the beer, pitch entire thing (sans stir bar). Should wake up all the yeast, get them ready to eat, and bring them back to temp. EDIT: Gets the best of both worlds, the starter is the same exact base as the beer you are making, it isn't oxidized, it gets O2 to the yeast, you are pitching highly active yeast.
