starter from 90ml harvested yeast?

Ingredients
1

Hi all,

Going to do a beer next week (1048 OG, 5.5 gal batch).  I harvested Calif. ale yeast WLP001 last night from a previous batch I bottled.

According to Mr. Malty, I need about 90ml of repitched slurry to do the job.  That seems to be right about what I’ve got in one of my jars.  Actually, if I adjust the date back a week (since I won’t pitch this for another week), it says I need 103ml.

I have two questions:

  1. should I do a yeast starter, or would that be too much yeast (I assume about 180ml)? Or, is it for some reason not good to do a yeast starter from harvested yeast in the first place?

  2. I left the yeast concentration and non-yeast % on Mr. Malty at the default because I had no idea how to assess this.  Any thoughts?

Thanks!

2

I would just pitch it.

3

The viability loss estimations in the Mrmalty calculator are not the best.  Check the viability estimates in this calculator.  Seems to be much more reliable.

4

I agree. You’re repitching in a short enough timeframe that it can grow in your next batch rather than grow in a starter. As long as you aerate well and control your temp you should have plenty of healthy yeast to get the job done well.

5

That doesn’t cover slurry.

6

The calculator is for estimating the viability of the yeast in the slurry.  You can use Mrmalty to estimate the percentage of the slurry which is yeast.

7

Thanks, all!  I’ll skip the starter this time.

blair.streit:  Your comment makes me wonder…if I’m going to use the slurry in a week, should I take it out of the fridge now?  Just sounds like you may be assuming I’m keeping it at room temp in the meantime.

8

I had always believed these to be vastly different. Maybe Mark has some research based thoughts.

9

The yeast health will be best if you store it cold (around 40F) and then let warm to pitching temp within 12 hours of brew time. The longer you leave them at warmer temps with nothing to eat, the weaker they get.

10

Keep the yeast cold until you are ready to pitch.  No real need to let the yeast warm up.  They will quickly acclimate to the warmer wort temps.

11

This.  I’ve actually seen some evidence that colder yeast into warmer beer is preferable.  Not to mention it’s worked great for me for hundreds of batches.

12

Now I’m curious – what kind of deltas are you guys talking about? I agree that for purposes of the OP’s question it’s no big deal, but I like to overthink things :wink:

I tend to do this with lagers when I’m pitching 40F-ish slurry into 45Fish wort. But are you guys saying you’re pitching 40ish slurry into 65ish ale wort?

13

I take the yeast out of a 40ish fridge and directly pitch it into a 65ish wort.  No problem, great results.

14

Cool. That could save me some steps :slight_smile:

15

Ninety milliliters of slurry will get the job done. If you want a better grasp of how yeast cultures grow, you should read “Yeast Cultures Are Like Nuclear Weapons” (Yeast Cultures are Like Nuclear Weapons | Experimental Brewing).

16

Denny, I used to let my yeast warm up a tad prior to pitching until you mentioned it was unnecessary. Now it goes straight from the fridge into my cool wort.

17

UPDATE from OP:

Unexpectedly ended up brewing yesterday rather than next week.  Pitched yeast slurry (no starter, as recommended here) around 6pm last night.  As of 7am today, the fermenter is chugging away!

It is my first wheat beer–the wort looks different than anything I’ve done.  Boil was different, too–the hops and other gunk caked the sides of the kettle.  I accidentally covered the top completely right at the end of the boil (I like to cover at least a part of the kettle to decrease chance of bird sh-t) after doing a 5 min hop addition, and it bubbled up and out.  Seemed to be mainly hops, so I threw another 0.5oz in…oh, well.