[hopshead]

Recently, I have started re-using yeast from batch to batch by getting (top cropping) ale yeast.  Currently, I brew every two weeks and my procedure has been this:  Brew one day on the weekend, then the next day make a 2 quart starter with DME and top crop 1 cup of yeast and put that in the starter.  After the starter ferments out (about 4 days or so) I chill the whole starter for a little over a week until I brew again, in which I let that starter warm up to room temp and pitch the whole volume in the beer.  So far, about 7 or 8 batches, I have had good results (using White Labs WLP001).  Next May, my wife and I are expecting twins and this will most likely greatly limit my homebrew days (not every other week like it is now).  I have been planning ahead, a I likely will double my all grain batch size to 10 gallons and brew once a month if time permits.  Now, finally to my question, will the yeast keep in the starter in the fridge for 3 weeks?  Or, should I learn how to somehow keep the top cropped yeast on an agar?  I am just curious.  I would rather not buy a new pitch every brew day.  Side note:  as of now, I plan to buy a new pitch everytime I re-order bulk ingredients, just in case the yeast I am using starts to "genetically" drift.  Thanks in advance guys and gals.

[The Professor]

I've kept saved yeast in a foil covered flask in the fridge (under its own beer)  for more than a month with no performance issues whatsoever.  I manage to get a brew in every 4-6 weeks, but sometimes it will stretch to 8 weeks, but still it presents no problem.

 No issues with autolysis either, though this would likely vary according to yeast strain.

[budweiser]

hopshead - another thing you can do to save yourself some hassle is to stop top cropping and making starters....just collect the slurry at the end before you keg/bottle.

What I do is rack the beer off except for an inch above the yeast in the primary. Then transfer the entire slurry (careful to maintain sanitation) to a flask.

I allow a little bit of the residual beer to come along for the ride into the flask. I cover this with some foil and put it in the fridge. If I am going to use this within in a month or so I just leave it and then drain off the beer before I pitch the slurry. This will settle over time and the break/hop matertial will go to the bottom, beer to the top, and the yeast in the middle. So when I pitch it I try not to pour the last few inches in and as I stated above I drain the beer off.

If I am going to save a yeast for a long time I will do the same procedure as I stated above for the most part. Once in the fridge and in the flask I let it settle(a few days or so). I then drain off the beer and transfer about 1 cup to a sanitized mayo jar with some distilled water in it. Maybe say a cup of water. I then put the lid on, label, and date it.

With this yeast I will make a starter if it has been sitting for a long time....however with the fresh slurry I have never found it necessary.

If you haven't already listened to it there are a couple of podcasts on the The Brewing Network about yeast handling/washing that I would recommend you listen to.

[hopshead]

budweiser - I have listened the brewing network podcasts and I actually got inspired to reuse yeast from those podcasts.  Saving the slurry is not "off the table" for me and I will consider this step.  I actually was very intrigued with "Tasty" McDole's method of top cropping and getting "superyeast."  I don't have the means to actually test and know for sure, but I speculate the top cropped yeast is more viable than slurry?  I also am curious if the "ill effects" of reusing slurry from high gravity brews applies to top cropped yeast, especially if collected within 24 hours because I don't know if those yeast have been exposed to the high alcohol toxic environment long enough to be detrimental.  I also wonder if they hopping rates affect top cropped yeast differently than slurry.  Maybe a member of the brewer's association or even better yet a yeast lab could elaborate on this.  To me it is a very interesting topic.

[budweiser]

hopshead - you make some great points.

Yes with high gravity beers I would recommend not re-pitching a slurry for most of the reasons you cited. However normally I would be using a second or third generation of yeast for a high gravity brew and then not re-using that yeast afterward.

IMHO As far as the viability and health of the yeast I think on the scale that we are talking about (homebrewing 5-15gal batches) there is little to worry about. As long as you maintain sanitation etc.... In the 5 years I have been doing this I haven't seen the ill effects of hop matter when re-pitching either. I could imagine if you dry hop'd then tried to collect yeast etc but generally I have little to no hop matter when I collect my yeast.