Mr Malty's slurry

[Vossy1]

Just been having a look around at the Mr Malty site at re-pitching slurry rates and it's raised a few queries.

What is the non yeast component of a washed yeast slurry?
It's set at 10% as slurry but there's no mentin of washing

What constitutes a thick and thin slurry?
I tend to pour most of the waste liquid above the yeast away, so does this make it thick yeast?

Checking the harvest date versus viability, storing a harvested slurry for 1 month reduces the potential viability from 94% to 44%...is that right :hmm:

 

[steve_flack]

I have no reason to disbelieve it. Yeast slurries in general keep very badly.

 

[subsub]

I have the opposite opinion to Steve and Mr Malty. I have never seen the viability drop that far even after 4 months on white lab yeast.

 

[steve_flack]

Whitelabs is different to harvested slurry. It's purer to start with and is more stable. We're talking about harvested slurry from a fermenter.

In any case, try a really fresh Whitelabs tube (a couple of weeks) old and compare it against a four month old one and come back and tell me you can't tell a difference.

 

[MEB]

I'd tend to agree with SF. In my own experience slurry is never as effective as a fresh starter and i tend to use about 3-4 times the amount that i would from a nice healthy starter. But slurry is what you'd normally throw away so your getting more use from your yeast. I guess it balances itself out in homebrewing.

This may well be down to my technique and limited brewing experience. But i find if i can collect some slurry, wash it a bit-i mean a tiny bit and re-pitch it then it's usually raring to go. But if i collect some slurry, wash and store for a while then it's never as responsive-for want of a better word-as fresher slurry or a good starter.

SF probably has a good take on why it isn't?

 

[subsub]

I am talking about slurry. I think Mr Maltys viability from 94% to 44% is a tad extreme.

 

[steve_flack]

I suppose to really tell you need to get a microscope and some methylene blue to do a count.

 

[MEB]

I am talking about slurry. I think Mr Maltys viability from 94% to 44% is a tad extreme.

I'd imagine that's about right. Potential viability just means the amount of yeast cells that are likely to still be active and not lazy old fat buggers. As i use about 3-4 times the amount of slurry to starter then my experience would have that even lower than 44%. It's not really an issue though-just use more slurry.

As i've stated-this is just my own personal experience and i'm no scientist or expert brewer.

 

[subsub]

Well we'll just have to agree to disagree, I use the freshest White Labs as I have 3 Brothers and 1 Sister who live over the pond who post it to me when required, and to be honest even the slurry peforms better than most of the stuff you can buy here. I use maybe 5% more slurry than in a vial but because the yeast is soooo much fresher it still takes off like a rocket even after 3 re pitches :thumb:

 

[Oblivious]

Checking the harvest date versus viability, storing a harvested slurry for 1 month reduces the potential viability from 94% to 44%...is that right :hmm:

maybe the calculator presumes you a going to re-pitch the yeast directly from the fermentor into the wort

I might be trying this in a few weeks, the calculator suggest 250-300ml of slurry into 25 literos of 1.08 wort, I might add a little more to be safe

Any suggestion would be of help