[richardt]

I've been kinda busy.  I've had a yeast starter (Wyeast 1056) going for over a week now (1L size, 1.040 OG).  Nice and creamy yellow color, still got a small dimple in the top of the fluid. 

Assumming the yeast are done eating all the sugars and have attained maximum growth and reproduction, am I harming the yeast by keeping it on the stir plate and aerating it?  (Air only, no Oxygen).

[bluesman]

Once the yeast has finished fermenting it's no longer necessary to stir. Cold crash and decant before pitching.

[tom]

Not with air. But definitely decant before pitching.

[narvin]

If you're not pitching at high krausen, you'll want to refrigerate it once it ferments out.  It's not so much the air, but the warm temperature and waste products that could lead to decreased viability over time.

[richardt]

Thanks gents,

I'll take it off the stir plate and put it in the 40F fridge tonight to cold crash it.

It'll be good for a few days, right?

I still have those yeast cakes from my IPA (can't wait to check and see if they've been good or bad (acetobacter).)

[majorvices]

As an aside and somewhat along the same lines I have killed a yeast starter with pure o2 before. But it would be impossible to do this with pumped air or on a stir plate.

[astrivian]

What is "cold crash"?

[a10t2]

What is "cold crash"?

Putting the starter (or main batch, for that matter) in the refrigerator. It forces the yeast to go dormant and flocculate more quickly.