Reusing a yeast cake

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Hi Guys,

I racked a porter on Monday evening, left behind a cm or so of beer ontop of the yeast cake, then stuck the lid on and put it in my garage. Which at most is around ~10c.

I'm looking at brewing a ESB at the weekend prob Sunday PM...

My question is should I dump the cooled wort onto this cake or play it safe and use a new dried yeast packet?
I'm worried that leaving the cake for 6 days might be a no-no?

Thoughts?

ohh it's Safale S-04 if that has any bearing.

[far9410]

Would have been safer to decant the yeast at time of bottling into a sanitised container, then keep covered until needed

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I was pretty careful when racking off, left the lid on during and after, etc.
I was thinking of moving it, but then thought the extra risk of infection wouldn't be worth it.. do you think it's better to do that now or leave it undisturbed till sunday?

[far9410]

its impossible to say, it is probably ok, but you're in a better position to know that

[Kev888]

There are three main reasons I re-use yeast: cost, selective breeding and not having to step up to a starter. But S04 is cheap, vigorous from the first generation, and doesn't need a starter, so personally I wouldn't feel the increased risk of infection from a week old cake is worth the small saving. If the beer wasn't infected and the FV had the lid on it would 'probably' be okay, but you just couldn't be sure.

Cheers
kev

[BarnsleyBrewer]

I've collected it a few times and thrown it back in the fermenter the week after but would never put fresh wort on without giving the fermenter a good clean to remove the old trub ring..
I'd say it'd be asking for an infection doing it that way, might be wrong but I'd never do it..

BB

[subfaction]

But S04 is cheap, vigorous from the first generation, and doesn't need a starter, so personally I wouldn't feel the increased risk of infection from a week old cake is worth the small saving.

True true, I think my old tight ass Yorkshire tendencies are leading me astray, that and perhaps wanting to see my beer climb out of the FV for the first time

£2 saving for 6 hours work... going to go for a fresh packet me thinks...

[Blackaddler]

You also need to pitch the correct amount of yeast for your new brew.

Don't just dump onto an old yeastcake of unknown quantity.

Save some of the yeast, by all means, but use Mr. Malty's Pitching Rate Calculator before repitching.

[nicksonic]

i've only just started reusing yeast as i've moved over to liquid. i just divided most of the yeast cake (plus some beer) from the original fermentation into 6 plastic bottles (about 250ml each), kept them in the fridge and then brought them to room temp and pitched when i needed. it's all worked so far...

i've seen that yeast shouldn't be used beyond the 3rd generation and keeps for a couple of months. is that about right?

[Blackaddler]

That's a reasonable rule of thumb...

[zgoda]

Some strains are stronger than others, but 5 generations is safe assumption. Not counting hefeweizen yeast, these go awol after 2 or 3 repitches.

[Kev888]

A lot depends on your methods too - if you stress the yeast or give them inconsistent conditions during fermentation they can change character more quickly, and also the risk of infection is cumulative so it depends on how good your sanitation is as to how far its wise to push it.

I'm not really set up to do things as properly as I'd like and I'm no great yeast expert to begin with, so whilst I'll happily go to a few generations I start to get a bit twitchy after that. I figure I'll have saved the extra cost of liquid yeast by then, and as I do 80L batches any problems would be quite costly.

One day, I tell myself, I'll be autoclaving, cell counting and breeding up selected colonies but currently it tends to be splits and recovered slurry in old water bottles and that kind of thing so i try not to let my expectations get too ambitious.

Cheers
Kev

[shazza]

youngs cider yeast with apple juice:multiple(x8) at least success rate.but I do hear that the apple is more tolerant than the grain regarding messing about.

[shazza]

Where am I ?.......Jayzuz get me out of here quick.

[BozBru]

Dumping on a used yeast cake takes a considerable act of faith, and also a good element of timing. These type of things are considered an advanced form of brewing, albeit home or commercial. A simple act of dumping, will negate the use of a new yeast for anything up to three brews, after that, you have no control as to how the yeast will "develop". This, of course, will depend on the type of beer you're aiming for. But who can afford to brew the same style for more than three weeks anyways. Unless, of course, you happen to be a home brewer, in which case your tastes are going to be consistant.

I happen to think that unless you are particularly succeptable to a certain style of beer, then it's not worth it. UNLESS......you decide to go down the route of liquid cultures. You should be able to make a liquid culture stretch to at least 3 brews, although 6 - 8 is not uncommon.