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General Category => Yeast and Fermentation => Topic started by: tomsawyer on December 05, 2011, 09:15:06 PM

Title: Re-using Yeast for Starters
Post by: tomsawyer on December 05, 2011, 09:15:06 PM
I generally use a yeast for several generations, and keep yeast cake in 8oz sterilized jelly jars.  I should also mention I brew 3gal batches for the most part.  Typically I'll pitch these into 1L of starter wort the day before (or sometimes the day of) brewing.  i think it gets the yeast revved up before pitching them into the abyss of a 3gal batch of wort.

My question is, should I be adding less of my yeast cake to a starter in order to get some new growth?  Am I even getting a doubling of cell number with a heavy pitch like this?
Title: Re: Re-using Yeast for Starters
Post by: tschmidlin on December 05, 2011, 09:30:32 PM
How much is in the jars?  If it's a full 8 oz, I would use less.  Much less.
Title: Re: Re-using Yeast for Starters
Post by: beersk on December 05, 2011, 09:38:37 PM
How much is in the jars?  If it's a full 8 oz, I would use less.  Much less.
There's probably a lot of trub in there too.  I was kinda wondering the same since I parce my yeast cakes off into 3 or 4 pint mason jars.  I've been pitching a whole jar without a starter. 
Title: Re: Re-using Yeast for Starters
Post by: tomsawyer on December 05, 2011, 09:39:17 PM
Yes at least 6oz, and usually close to full.  I've been successful rousing yeast after two months this way.  But I do think you're right, I should be using about the same amount as you see in a Whitelabs vial which I would guess to be closer to 1oz.
Title: Re: Re-using Yeast for Starters
Post by: tomsawyer on December 05, 2011, 09:40:25 PM
I suppose there some trub although I've been doing better about leaving the break in the kettle and I strain out the hops so I would guess the cake is 2/3 yeast or more.
Title: Re: Re-using Yeast for Starters
Post by: beersk on December 05, 2011, 09:44:25 PM
I suppose there some trub although I've been doing better about leaving the break in the kettle and I strain out the hops so I would guess the cake is 2/3 yeast or more.
Gotcha.  I don't really have a good way to leave out the trub and hops.  I just try to leave it in the kettle when I'm pouring into my fermenter.  Maybe I should get a strainer of some sort.  I also don't save yeast from highly hopped beers.
Title: Re: Re-using Yeast for Starters
Post by: denny on December 05, 2011, 10:01:48 PM
How much is in the jars?  If it's a full 8 oz, I would use less.  Much less.

Tom, what's the downside of using 6-8 oz.?  Less healthy yeast?
Title: Re: Re-using Yeast for Starters
Post by: tomsawyer on December 05, 2011, 10:02:58 PM
You can't really strain out trub very well, the hop pellets seem to be caught fairly well though and they form a filter cake that does catch a little break.

Why don't you save yeast from hoppy beers?  I'd think you could let the beer settle off the yeast, decant that and maybe wash with some boiled/cooled water to bring it to a neutral flavor point.
Title: Re: Re-using Yeast for Starters
Post by: tschmidlin on December 05, 2011, 10:34:10 PM
How much is in the jars?  If it's a full 8 oz, I would use less.  Much less.

Tom, what's the downside of using 6-8 oz.?  Less healthy yeast?
6 oz of yeast is about 5 white labs vials.  That is a lot to add to a one liter starter, and for a 3 gallon batch.  I don't know if there's a huge downside really, but it's just not necessary and I would stick with more conventional pitching rates.

I don't worry about yeast health per volume like that - you have more unhealthy yeast, but more healthy yeast too.  If it is a fresh and healthy slurry, I'd skip the starter and just direct pitch an appropriate amount of yeast.  If you are worried about the health of the yeast, like if it's been sitting around for a while, then make a starter of appropriate volume and pitching rate for the beer you're making.  But I would use a bigger starter, that much yeast in 1 liter isn't going to give you much growth, if any, and might not really be energizing your yeast.

A fresh 6 oz slurry of yeast is more than enough for 5 gallons of a 1.100 beer, in 3 gallons it should be enough for anything Fred would throw it in :)

This all assumes ales of course, lager pitching rates will be higher.  And seriously Lennie, if you like your beers then don't change on my account.
Title: Re: Re-using Yeast for Starters
Post by: bluesman on December 05, 2011, 10:50:06 PM
I've used harvested yeast cakes for making starters over the years. I usually rinse the yeast with some sterile water and make a starter at that point. Although, it's really hard to know what percentage of the yeast cake is live yeast, hence the "make a starter" to be sure method. I've pitched directly onto yeast cakes for some of my really big beers but tend to be more concerned with the pitching rates as of lately. Overpitching may adversely affect beer flavor but you'd have to experiment to determine the real impact based on the level of overpitching.

In theory overpitching would mean less growth and potentially less esters whereas underpitching the opposite occurs, excessive cell growth leading to more esters ultimately impacting beer flavor accordingly.

Title: Re: Re-using Yeast for Starters
Post by: tomsawyer on December 05, 2011, 11:59:40 PM
I've often thought the high pitch to a starter would prevent the yeast from "getting their bud on" before nutrients ran out.  It does let you know about the health of the yeast though.  It works but I think I'll use more like an ounce for a starter when I have time.  I do enjoy reusing yeast, it kind of let's me rotate what I brew based on what yeast is fresh and ready to go.  Plus with small batches it reduces the cost of that ingredient significantly.
Title: Re: Re-using Yeast for Starters
Post by: cheba420 on December 06, 2011, 04:19:46 AM
I usually rack my beer off of the yeast and then rinse the cake with some boiled, cooled water. I let it sit for about 20-25 minutes. The dead yeast drop to the bottom and I pour the good stuff into a couple of sterile mason jars for later. The mason jars have measurements on the side of the jar. Check mr.malty.com and use the calculator to determine how many ml you need to ad to your wort for the proper pitch. Seems to work great for my ales. My only question on this practice is how long the yeast is good for once Its in the mason jar and stored in the refrigerator.  I've had great results with anything less than a month old. Never really used any that were older than that.
Title: Re: Re-using Yeast for Starters
Post by: tschmidlin on December 06, 2011, 04:47:32 AM
It will last a long time, potentially a very long time if you use distilled water.  But after 3 months you might want to make a starter or pitch extra.
Title: Re: Re-using Yeast for Starters
Post by: cheba420 on December 06, 2011, 09:00:39 PM
It will last a long time, potentially a very long time if you use distilled water.  But after 3 months you might want to make a starter or pitch extra.
Good to know. Thanks, Tom! Looks like I've been throwing away good yeast!
Title: Re: Re-using Yeast for Starters
Post by: tschmidlin on December 06, 2011, 09:58:29 PM
It will last a long time, potentially a very long time if you use distilled water.  But after 3 months you might want to make a starter or pitch extra.
Good to know. Thanks, Tom! Looks like I've been throwing away good yeast!
Maybe, but you should have plenty from your fermentations, right? :)
Title: Re: Re-using Yeast for Starters
Post by: tomsawyer on December 06, 2011, 10:13:12 PM
It will last a long time, potentially a very long time if you use distilled water.  But after 3 months you might want to make a starter or pitch extra.
Good to know. Thanks, Tom! Looks like I've been throwing away good yeast!
You're just stimulating the economy.
Title: Re: Re-using Yeast for Starters
Post by: wildknight on December 07, 2011, 01:53:05 PM
I like to rinse the yeast cake 3-4 times with boiled, cooled water.  This lets me get the trub out (what falls out first) and the dead cells (what falls out last).  Then, I calculate the pitching rate using the lowest setting for trub on the MrMalty app.  If it is older than a week, I give it a little wake up juice starting the morning of brew day (to be pitched ~ 12 hours later).

I will save yeast from APA's, but generally not IPA's as I late hop them heavily and go high gravity.  This really stresses the yeast and coats them significantly with hop oils.  I believe the theories, as from my own experience it takes a lot more effort to clean yeast cakes from these types of beers, and I observe a lot more dead, floating cells during the washing process.  If I dry hop in the primary fermenter, then I don't even consider saving the yeast cake.  It's nearly impossible to get the yeast clean.  If you transfer to secondary, then you can dry hop all you want without ruining your yeast cake.  However, the trade-off is that you have to let fermentation complete and wait for the yeast to completely flocculate and settle otherwise you will begin selecting for early flocculators.  This prevents you from throwing in the dry hops when fermentation is 2/3 complete, thereby letting the yeast soak up any oxygen that comes in with the hop pellets. 

Usually, I use the american yeast strains on hoppy beers.  Since these only cost $1-2 per dry packet, I don't worry about not saving the yeast.  For all other beers I use specialty, liquid strains and put in the extra effort to keep the cakes going. 
Title: Re: Re-using Yeast for Starters
Post by: Pi on December 07, 2011, 02:59:20 PM
On Sunday I racked a stout using Wyeast 1084. I had a yeast cake with about 1/4" of beer on top. I swirled the carboy around to mix with the beer and to loosen up the cake and then poured it into a 12oz. bottle. MrMalty says use 3.8oz. in my Scotch Export. Should i be mixing as stated, or should i harvest only cake? What role does O2 play at this point?
Also, when You talk about washing the yeast, could you elaborate how this is done? I mean, is it simply a matter of mixing with clean water; settle out and rack off the liquid in suspension?
Title: Re: Re-using Yeast for Starters
Post by: wildknight on December 07, 2011, 03:18:58 PM
In a nutshell, stuff that falls (well shaken, no obvious clumps) within 10-15 minutes is trub.  Stuff that won't fall out in 12-24 hours (in the fridge) is dead yeast.  Remove both using sterile/boiled water.

Here is a nice, detailed podcast on the subject:  http://www.thebrewingnetwork.com/shows/543