Harvesting yeast

[Paindoc]

I'm sure more experienced brewers on this forum have experienced this before but I've never seen anything like this!
I made a weizen 10 days ago and then made another batch today. Instead of buying more yeast I drained 2 quarts of yeast sludge from the bottom of the conical fermenter with the first batch in it (end of primary fermentation) and pitched it into the new batch. There was bubbling in the airlock within an hour, vigorous bubbling in 2-3 hours, and full kreusen in 4-5 hrs. I'm used to about a 12 hour lag time even when using a large starter. Is this typical when re-using yeast from a completed primary? If so, I'm going to do this more often.

[piper55]

 you pitched a large amount of yeast so sure you can get a fast ferment.I usually brew 3 weeks in a row so I can keep reusing the yeast.

[Maine Homebrewer]

I will often stretch out a single yeast packet for four or five batches. Each time I pitch the dregs of the racked batch the new one takes off like a rocket.

[brewark]

If you are willing to make a starter from it, you can "wash" the yeast & store it in the fridge for quite a long stretch, rather than brewing on the yeast's schedule.  Something to google. =-)

[Whitefish]

I've 'harvested' yeast several times. Always with great success. As piper55 said, you are pitching a large amount of (hopefully) very happy yeasties.
Most recent example is a pair of Kolsch. First brew day was Feb 18. Wyeast 2565. OG= 1.047. Second brew day March 3. OG=1.047. Washed and repitched the yeast from batch one. As of March 17 batch one is at 1.011 (when racked to secondary on 3/3 it was at 1.013) and batch two is at 1.010. The difference of .001 is too close to say there is a real difference in attenuation, but clearly the repitched yeast took off faster.

[mglowe]

Yep! My first attempt to harvest yeast did much the same... I knew at the first hour of the starter I was in for something wild.

I harvested about 150 ml and later pitched it all to a 1.5 l starter figuring I may not have harvested correctly...? Surprised me my starter is going like mad. I needed only a portion of the starter but noooooooo. I had to pitch the whole thing and a what mess I had.

Bubbling in the airlock just as you described that required me, the next day, to remove the airlock entirely. I was doing everything I could to contain the activity. Activity was insane.

I've read somewhere that over-pitching will end in minimal AAT production which has something to do with the production of esters. This maybe good or bad according to your beer style. Someone please correct me if I'm wrong.

[madchef77]

 mglowe -  I harvested about 150 ml and later pitched it all to a 1.5 l starter figuring I may not have harvested correctly...? Surprised me my starter is going like mad. I needed only a portion of the starter but noooooooo. I had to pitch the whole thing and a what mess I had.

ha ha ha ha ha ha ha ha I am glad you posted this because my brother and I didnt want to buy another yeast pack and sure enough we put the entire batch of activated yeast and when I came home from work, there was beer everywhere. 

so hear is a question I was goin to post today.  how much of the activated yeast are you supposed to use?

[rrbrewer]

When the fermentation bubbles through the airlock, should you hook up a blow off tube into a container with some sanitizing solution to avoid the mess.   

[dharalson]

mglowe -  I harvested about 150 ml and later pitched it all to a 1.5 l starter

WOW!  There is about 4-8 BILLION yeast cells per ml of settled slurry.  That's about 600 Billion cells, enough for several batches of beer! !  It has been my experience that yeast will grow to fill the volume you have.  Try a couple of experiments, Pitch 1 ml of yeast into one starter and pitch 10ml of yeast into another starter of the same size.  In the end you have about the same amount of yeast which will be about 100-200 million cells per ml of starter.  So a 1500ml starter will max out at about 150-300 billion cells.  This does assume you are using a stir plate.

Yeast in an anaerobic environment (no oxygen) will create CO2 and alcohol.  Alcohol will slow the yeast down.  In an aerobic environment (lots of oxygen, ie stir plate) yeast will produce CO2 and water.  Yeast reproduce by splitting (or doubling) so their growth is exponential.  In their happy place they will double every 2-3 hours so in two days there can be as many as 20+ doublings.  That is a growth factor of 2^20 or 1 to 1,000,000,000.

Try the experiment and report back.

David

[PetenNewburg]

  I recently washed a primary from a porter.  I had saved about 3/4 gallon of sparge water from the same porter.  I reboiled the wort and added a half cup of DME to give it a 1.040.  I put a half cup of washed yeast/ 1/2 cup wort mix into pint jars and covered.  I mixed a pint of the washed yeast into a quart of wort and put it on the stir plate.  Less than a hour later it had puked all over the counter.  I did manage to save about a quart to use in a Irish Stout which also took off within a hour.  Made another Irish Stout a few days later from one of the refrigerated pints, washed that yeast/ primary and now have four 1 pint starters!

[dharalson]

Pete
When you store yeast for later use, you really want to store it in an inert as possible liquid.  You definitely do not want to store in sweet wort.  Even in the refrigerator the yeast is still slightly active and will continue to convert sugars in to CO2.  If you have yeast and sweet wort you need to vent the container VERY SLOWLY or it will react like a shook up soda on steroids.  I store my yeast in sterilized distilled water; but that is for very long term storage.  To store for a couple of weeks, I would suggest distilled water.  You don't want to provide anything for the to feed on; you want the yeast to go into a dormant state.  I read one article where the brewer stored yeast in PBR !.  I guess there is a use for it after all !

Good Luck, David

[PetenNewburg]

  Will do.  I was curious to see if it would work and did not want to waste the low SG wort.  When doing a big stout I save it for beef marinade.  My chickens love to dig through the spent grains!