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B-Dub
09/27/08 11:14 PM  
Cisco...how do you build up all that yeast?
Cisco,

I read that you brew some big batches. How do you build up your yeast? It seems that one of my issues is under pitching. Thanks for the help.

B-Dub

Cisco
09/28/08 01:03 PM  
Re: Cisco...how do you build up all that yeast?
I use a 2000 ml flask on a stir plate and add some pure oxygen occasionally. I add more wort a couple times until the flask is full and the yeast is finished then crash it in the frig and pour off the clear top liquid then start over again if I am making a high gravity beer. For our barrel projects there are five members that build up yeast for pitching.

For a 10 gallon batch I will create a 2000 ml flask worth of yeast.

B-Dub
09/28/08 04:48 PM  
Re: Cisco...how do you build up all that yeast?
So say you are going to brew 10 gallons of a Quad. Starting og is 1.080. You would build up one tube with 2000mls then dump the beer from the top and add 2000mls and use the yeast that produces?

Do you use the MrMalty's calc to help you figure out the size of starter needed?

Thanks, just trying to get my Belgium yeast handling down. Like you said, it is not your normal ale strain.

Cisco
09/28/08 06:18 PM  
Re: Cisco...how do you build up all that yeast?
Yes.

No.

petec
09/29/08 02:38 PM  
Re: Cisco...how do you build up all that yeast?
If you're going to take the time to make 4L of starter, would it be easier to just make a beer and then pitch the slurry into your quad? Thats the way I'd approach it.

petec

Cisco
09/29/08 02:48 PM  
Re: Cisco...how do you build up all that yeast?
That's another approach I use also sometimes when I want to use the same yeast strain again.
wolfsdenbrew
10/10/08 03:05 PM  
Re: Cisco...how do you build up all that yeast?
So you make an initial 2l starter with a vial of yeast, let it ferment out then decant? Then add another 2l of wort?

Will this really boost the yeast count? Seems to me after the initial 2l of starter the count would be high enough to ferment the next 2l without multipying. Or am I missing something?

Cisco
10/10/08 03:51 PM  
Re: Cisco...how do you build up all that yeast?
Yes.

Yes, but the addition is made in three seperate additions. If you added all that wort at once then you would see most of it on the counter top after it took off.

All this all happens on a stir plate.

You're only missing the fact that I really do want my yeast count quite high for my high gravity beers if it is a first pitch of a yeast strain. So yes, the initial 2L of yeast is enough for the next 2L of wort BUT I want even more yeast cells generated.

wolfsdenbrew
10/10/08 04:43 PM  
Re: Cisco...how do you build up all that yeast?
But it is my understanding that yeast only multiply up to the numbers they need to chew up the sugars, so if you have already promoted multiplication for 2l of wort, adding 2l more wort after they have already multiplied seems like it would not cause the yeast to multiply further.
Cisco
10/10/08 06:08 PM  
Re: Cisco...how do you build up all that yeast?
Oxygen is the great secret ingredient to forced multiplication.That's why you use a stir plate. Sometimes I even feed it some short bursts of pure oxygen especially when getting it first started.
B-Dub
10/10/08 09:59 PM  
Re: Cisco...how do you build up all that yeast?
Glad someone else chimed in here.

I am making a 11 gallon Quad with WLP530 in the next few weeks and plan on brewing a 5.5 gallon Golden to get the required yeast that is needed.

If I did not want to make a batch and planned on using a stir plate what are some step by step proven methods to produce the required healthy yeast count?

What is your method?

I don't want sweet beer this time.

Thanks for all the help.

wolfsdenbrew
10/11/08 10:25 AM  
Re: Cisco...how do you build up all that yeast?
Cisco...i am not disagreeing with anything, I understand that the stir plate increases cell count.

I just don't understand the biology behind it...as far as if you can trick the yeast into multiplying more than they need to for the existing 2l.

Cisco
10/11/08 10:59 AM  
Re: Cisco...how do you build up all that yeast?
Maybe Al can insert some yeast education info here on why they multiply with oxygen. I'm too lazy to look it up, I just know that it works after may years of brewing. I believe that it is the lack of oxygen that causes the yeast to stop multiplying and just eat.
Baums
10/13/08 11:06 AM  
Re: Cisco...how do you build up all that yeast?
wolfsdenbrew,

the source of confusion here is that this statement isn't true (even though some homebrewing books or articles might suggest otherwise):

"yeast only multiply up to the numbers they need to chew up the sugars"

Yeast multiply throughout the fermentation. This multiplication requires a lot of energy and that's why fermentation occurs as quickly as it does.

If multiplication is forced to stop (say, because the wort was deficient in some essential nutrient and it runs out before the ferment is complete) then the yeast no longer need so much energy. They only need enough to "stay alive." Therefore they ferment MUCH slower--so much so that we call this situation a "stuck ferment."

The brewing scientist Balling found that under the conditions he studied, about 5 grams of new yeast are created from fermenting 100 grams of sugar. We would say the "biomass yield" is 5% in that case. The biomass yield is found to be higher when there's more oxygen available, and vice versa. (Numbers I have seen are consistent with roughly 8% for a starter on a stir plate and 3% for a starter that's aerated just once.)

So, every time Cisco decants the spent starter and adds new wort, maybe 8% of the new sugars will be made into new yeast cells.

petec
10/13/08 12:46 PM  
Re: Cisco...how do you build up all that yeast?
Sterols are a big deal with yeast multiplication. I recommend a hearty search of the homebrewdigest from a few years ago.

I seem to recall that without oxygen, there can basically be only 3 cell divisions so 8 factor increase in yeast cell count.

Sterols effect cell membranes and since yeast multiply by budding, sterols then effect how many budding events can occur. Without enough oxygen, sterols are deficient and then not enough multiplication can occur.

This should give you a start......

petec

 
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