Pitching on to a yeast cake that is highly flocculant

[billpa]

Im planning on brewing an English style Brown Ale next week. After its done fermenting I would like to brew a Milk Stout and pitch it onto the yeast cake from the Brown Ale. I am going to use White Labs 002 English Ale yeast which is highly flocculant. When I pitch onto the cake, should I make an effort to get mix it real well to get it back into suspension?

TIA,
Bill

 

[olllllo]

This is just conjecture on my part.

Since fermentation has already started (duh Yeast cake), you have to be careful not to aerate.

Since you keg, throw some CO2 into the carboy.

I'd say gentle swirl at most.

 

[FSR402]

This is just conjecture on my part.

Since fermentation has already started (duh Yeast cake), you have to be careful not to aerate.

Since you keg, throw some CO2 into the carboy.

I'd say gentle swirl at most.

so you're saying that when you pitch onto a yeast cake you should not aerate the wort?
Why not? It's a new brew with nor O2 in the wort.

 

[cclloyd]

I pitched a dunkel onto a hefe cake and basically just poured the pitch temp wort into the primary containing the cake and it mixed thoroughly during the pour. I had no ill effects, the dunkel fermented beautifully and came out great.

 

[olllllo]

so you're saying that when you pitch onto a yeast cake you should not aerate the wort?

Why not? It's a new brew with nor O2 in the wort.

That's what I'm saying.

I'm re-reading Palmer.
http://www.howtobrew.com/section1/chapter6-9-3.html

I may be wrong, but Primary fermentation has occured.

In addition, if oxygen is introduced after primary fermentation has started, it may cause the yeast to produce more of the early fermentation byproducts, like diacetyl.

And my other assumption is that this (below) has already occured.

Yeast need oxygen to synthesize sterols and unsaturated fatty acids for cell membrane biosynthesis. Without aeration, fermentations tend to be underattenuated because oxygen availability is a limiting factor for yeast growth—the yeast stop budding when sterol levels become depleted.

That was the basis for my thoughts. Someone else can opine and set me straight.

 

[Orfy]

O2 is required for yeast multiplication.
Once the orgy is over then the feast begins and thats when they start to piss ethanol.

I think OlllllllllllllllO put it better though.

 

[Blender]

WLP 002 gets pretty compact. I think I would mix it up before adding the fresh wort. It should work really well and use a blow off if you have one.

 

[olllllo]

I'm still re-thinking this, because the yeast cake is essentially one big starter.
Hmmm.

 

[billpa]

Sounds good. I dont do a full boil so perhaps I will add some water (with same temp as fermentation) to the yeast cake, swirl it around a bit to get it suspended again and then rack the wort in. I will make sure to have a blow-off hose. I suppose it will get rather turbulent?

 

[Orfy]

It will benefit from some agitation.

 

[billpa]

It will benefit from some agitation.

yup...definitely!

 

[jelsas]

I think ollllllllllo is right, and I think I have the proof in bottles.

I brewed a Kolsch a few months ago, then after ~3 weeks in primary, I transferred to secondary & pitched another on the yeast cake. I shook the hell out of it, thinking I needed the o2 & to mix up the yeast. BUT, lo and behold, when I bottled the two batches a few weeks later, the second had a HUGE diacetyl taste

I've been trying to figure out what went wrong with the second batch -- of course it fermented much faster (being pitched on the yeast cake), but I didn't think that would produce the off flavors. It was in the primary for 10 days and SG was stable. I guess I *could* have racked too soon, but I doubt it. So, my shaking the carboy really might be the reason for my buttery-tasting beer.

 

[FSR402]

I'm still re-thinking this, because the yeast cake is essentially one big starter.
Hmmm.

That's what I'm thinking.
From what you posted from HTB I take that as he's talking about after the brew has fremented. Well, that brew is done and racked out. The brew you are putting on top is not done and thus needs O2. Because the yeast cake is as you stated, just a big starter.

 

[olllllo]

It really boils down to whether the cake is ready to continue "feasting" and make alcohol and CO2 or if the colony has to regroup and make more guys.

IDK.

 

[DeathBrewer]

from what i understand, o2 is only necessary for yeast to multiply, so why aerate when you have plenty of yeast already in the fermenter?

you may wish to agitate, but it won't matter. those yeast will find their way into the wort and have a hay-day.

 

[david_42]

Stir it well to re-suspend the yeast and break up the clumps. If you had a big whisk, that would be idea. Aeration really isn't necessary, since you have a huge population, but it isn't going to hurt the batch in any way.

 

[FSR402]

Stir it well to re-suspend the yeast and break up the clumps. If you had a big whisk, that would be idea. Aeration really isn't necessary, since you have a huge population, but it isn't going to hurt the batch in any way.

So lets just say, dump the wort in there and mix it up but don't bother busting out the O2 tank ans stone.