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General Category => Yeast and Fermentation => Topic started by: cliebaert on September 19, 2013, 05:44:35 PM

Title: Pros and Cons?
Post by: cliebaert on September 19, 2013, 05:44:35 PM
Having a debate with the wife about the pros and cons of culturing yeast from past brews. Would like to get feedback from those that do it.

Few questions:
How time consuming is it?

Does it take up much space/supplies needed?

Anything would help
Title: Re: Pros and Cons?
Post by: Jimmy K on September 19, 2013, 06:03:34 PM
Assuming that you'll use the yeast within a few weeks of harvesting, you don't need much more than a few mason jars or other sanitizable containers. You also need some fridge space to store yeast.
Pros: FREE YEAST!! Healthier, fresher yeast if you do it right. You get to tell people you have a 'house yeast' and sound cool.
Cons: Some extra equipment and work - more than dry yeast anyway. If you're doing liquid yeast and starters, it's probably a similar amount of work to that. Contamination or yeast mutations if you do it wrong. Longer term storage might require more work.
Other considerations:  You might need to brew on a more regular schedule to take full advantage. You also need to brew beers that require the same strain.
Title: Re: Pros and Cons?
Post by: Joe Sr. on September 19, 2013, 06:26:27 PM
What do you mean by culturing yeast from past brews?  Do you want to use the dregs of a bottle conditioned beer?  If so, it's possible but your better off harvesting the yeast from your fermenter.

Culturing yeast from a bottle is no more difficult than making a starter except that you need to step up from a very small amount of wort to what ever size starter you're making.  You would start by putting some wort into the bottle with the dregs, shaking to aerate, and covering loosely with foil.  Wait a day or thereabouts, and pitch that into a small starter.  Repeat until you're at the starter size you need, decanting along the way if necessary.  Sanitation is very important, particularly so in the first few steps.

Again, you're better off just pouring the yeast cake from your fermenter into a sanitized container and re-using that.
Title: Re: Pros and Cons?
Post by: cliebaert on September 19, 2013, 06:46:33 PM
Thank you for your input, it is helpful.
To cultivate the yeast from the fermentor, I would pour the cake into several sanitized jars with some of the wort that was leftover, then put in fridge till the next time I brew. Then I pitch the yeast from that into the brew when it comes time. Am I missing anything?
Title: Re: Pros and Cons?
Post by: Joe Sr. on September 19, 2013, 06:52:35 PM
Pitch a portion of the cake (maybe 1/2 or thereabouts being completely unscientific) if you are pitching it within a week or so.

Beyond that, the viability is dropping so you either need to pitch more or grow it up in a starter.

There are on-line calculators that will help you estimate how much yeast you need.  Mr. Malty is popular, but there are others that have their fans as well.

If you use glass jars, you will want to vent the pressure occasionally so that they don't explode.  You will definitely get pressure building up in a closed container.
Title: Re: Pros and Cons?
Post by: svejk on September 19, 2013, 08:28:37 PM
My standard approach is to do the simplest process first and if it doesn't work for me then I add complexity as needed.  There was a thread a little while ago about how pitching on a yeast cake is a bad idea, but in my experience I've really liked the results - at least in certain circumstances. 

I usually schedule back to back brew sessions about a week or two apart with a smaller beer (ie a Scottish 60/- with Wyeast 1728) brewed first and then a big beer (like a big English Barleywine) brewed second.  During the barleywine boil, I rack the Scottish into a keg and leave the yeast in the fermenter.  Once the barleywine is chilled, I put it right on top of the yeast from the Scottish and let it rip.  My philosophy is that the carboy was sanitized when I put the first beer in there, so I don't even bother cleaning it out.  If you read the other thread about pitching on a yeast cake, you'll see that there are lots of opinions about whether this is a good practice or not, but both my beer that was selected in a Pro Am competition and my 41 point barleywine were brewed using this method so I have no complaints.

In my experience, using this method is best for yeasts that ferment clean - where the yeast doesn't contribute a large part of the flavor profile of the style.  German hefs and Belgian dubbels, tripels, etc. get too much of their flavor profile from the yeast and using this method hasn't worked well for me.  My hunch is that the large volume of yeast results in a situation where there is very little yeast reproduction and the lack of a lag time results in a lower contribution to the character in the finished beer.
Title: Re: Pros and Cons?
Post by: klickitat jim on September 20, 2013, 12:19:48 AM
I don't normally quote myself, just to lazy to retype... this was on another thread the other day. Hope it helps.

Given that many people just pour the wort right on top of the old yeast cake in the used fermentor,  you'll be fine. The problem is getting your pitch rate right. I estimate and then forget about it. If you look at Mr. Malty, and guess a low concentration of cells to be safe, and a high percentage of non yeast to be safe, then about 300ml of day old unwashed slurry is fine for 5 gallons of 1.060 ale. That's about a cup and a quarter.

What I'd do (just did this morning actually) is rack my beer off the cake. Leave a 1/4" of beer. Swirl that slurry up till there's none stuck to the bottom. Pour that into a sanitized quart jar and put it in the fridge. When you're ready to pitch just pour off the beer at the top and pitch a cup to a cup and a half of the yeast. Cup if you're wort is 1.040-60 cup and a half if over 60. If it's huge, like 1.070 or bigger you'll need more. Double if it's a lager.

Yeast in the fridge degrades over time. Personally,  I don't make a starter if I repitch within a week. If older, I make a starter with 100-150ml of slurry and 2000ml of wort. I try not to save my yeast past a month. I brew enough I almost never toss any.

This is the Klickitat Jim scientific method dumbed down to reality in the homebrew world.
Title: Re: Pros and Cons?
Post by: erockrph on September 20, 2013, 03:50:19 AM
If all you have to work with is an old bottle, then by all means have at it. I've done this recently with a beer I brewed last fall with a seasonal yeast strain after I learned that it isn't currently scheduled to be released again. I left a few beers from a relatively low gravity brew laying around specifically for this purpose as a sort of a "yeast bank".

Now that I have this yeast going in a brew, I'm planning on keeping it going by reserving some of the yeast cake, and repitching a stronger brew on top of the rest. I also saved a little from the initial starter and got another starter going with it. My plan is to use this as my house strain for a while, so it's worth my while to keep a small bank of yeast for now. I also plan on keeping a few bottles of a lower gravity brew from this batch tucked away in for longer term storage.