I'll try to answer questions I'm seeing above.
All this pertains to
stir plate starters.
This is info I consider to be solid, from reputable sources:
- Using DME, a rate of 100g/L of final volume will produce ~1.040 wort (if using a flask, add 100g/L final volume of DME, then fill to final volume with water & boil)
- Pitching a whole 1.6L starter into an IPA should not have a noticable impact on flavor
- If you're going to full pitch like that, do so in the 16-24 hour range (peak activity, most budding is complete)
- If you're going to decant first, leave on the stir plate for no more than 36 hours, then allow to rest for 8-12
- Do not run a starter for more than 48 hours maximum on the plate. After 48 hours, you're doing more harm than good since the yeast have consumed all available resources, and will begin to consume themselves
- After stirring, if you plan to rest & decant, optimally do not rest longer than 36 hours
- If rest must be extended longer than 48 hours (brew day got delayed... etc) give the yeast fresh 1.040 wort of at least original starter volume (or step up for multiple batches), and start the whole process over on the plate
These are things I do myself, that are just my opinion:
- Use the calculator
- I can my starter wort in 1Qt jars. This produces sterile ~800ml volumes per jar, with cold break material in the jar too
- Cold break material goes into the starter with the wort when I start, providing needed nutrients for the yeast, and particles for CO2 nucleation sites
- Stir for 24-36 hours at ~72f, regardless of strain. This has nothing to do with the temp range the yeast manufacturer recommends. We're making cells, not beer, so off flavors don't matter. Actual time is based on a visual inspection. When no more tiny CO2 bubbles are running up the inside of the flask and the yeast starts to come out of suspension, it's done
- Rest for 8-12 hours at desired pitching temp. Cool brewday wort to same temp. Decant spent starter wort, refill flask with brewday wort, return to stir plate for 15 minutes. Fill fermenters, pitch, huzzah!
With the yeast strains I have used (all White Labs) I have found a visual inspection to be the best way to tell when the stir is complete. The yeast will start to flocculate even while the plate it still running, which creates tiny clumps of yeast cells swirling around in the wort. It looks like swirling clouds inside the flask. I let that continue until there are no more visible CO2 bubbles coming out of suspension, and then shut it down. The bubbles are REALLY tiny, you've got to look quite close, in the uppermost 1/4" of the liquid. They run up the surface of the glass.
Again, this is based on my process. I run my plate at a speed where there is a dimple in the top of the liquid, not a vortex. If you ran it at vortex speed, I have no clue how that would change behavior.
I have never used a strain that flocculates so poorly that this visual test doesn't work. That said, it is possible that some will not flocculate in suspension and I just haven't seen them. In that case, I'd still use the bubble test in the 24-36 hour range.
I have used the following strains with my process, and all have given stellar results:
- WLP002 - English Ale
- WLP051 - California V Ale
- WLP004 - Irish Ale
Cheers!