Rehydrating dried yeast>

[PEACOCKSUIT]

I have only done this before on one occasion and didn't notice any difference. I m using good yeast in s-04 so is it really necessary or will airing the wort and then pitching be adequate?

Also when this one has finished fermenting, to reuse the yeast is it just a case of scooping some from the bottom of the FV and putting it in the fridge? Does anything else have to be done to it?

[boingy]

This is one that divides us.
It's good practice to rehydrate but in reality I'm not sure it makes a difference, especially with rampant yeast like SO4. I just chuck it in and it does fine. When I have rehydrated I have not noticed any great change in the behaviour.

I've only ever reused yeast once and I that was just as an experiment. I kegged a batch of bitter as usual and then rather than pouring away the yeast slurry and cleaning the FV I immediately put the new wort in the FV and stirred it all around to wake up the yeast. No cleaning, no sanitising, no nuthin'. What a cowboy. (OK, so I sanitised the spoon). The yeast got hold really quickly and made a really good beer. Not sure I'd make a habit of doing it though...

[HighHops]

I've only ever reused yeast once and I that was just as an experiment. I kegged a batch of bitter as usual and then rather than pouring away the yeast slurry and cleaning the FV I immediately put the new wort in the FV and stirred it all around to wake up the yeast. No cleaning, no sanitising, no nuthin'. What a cowboy. (OK, so I sanitised the spoon). The yeast got hold really quickly and made a really good beer. Not sure I'd make a habit of doing it though...

I've piggy backed yeast quite a lot and never had a problem. I usually only use half the yeast cake unless it's a strong brew, so that it doesn't foam over in the first 24 hours. It's better to go up in brew strength than down as brewing a high gravity beer can exhaust the yeast. But I find it gives a good pitching rate and generally good beer.

WRT 'No cleaning, no sanitising' - If you've just taken 5 gallon of beer out of your fv and it tastes ok, then your bucket should be germ/infection free, plus a high pitching rate means the next brew gets going in no time. If you're worried you can put the trub in a sanitised jar and separate from the yeast, while you sanitise the fv.

[HighHops]

I have only done this before on one occasion and didn't notice any difference. I m using good yeast in s-04 so is it really necessary or will airing the wort and then pitching be adequate?

I usually rehydrate just because if it looks or smells funny or off then I don't want to put it in my wort. It's meant to get it started quicker, but you can just bang the yeast in and it's usually ok.

Also when this one has finished fermenting, to reuse the yeast is it just a case of scooping some from the bottom of the FV and putting it in the fridge? Does anything else have to be done to it?

You can scoop it out the fv, but use a sanitised spoon and a sanitised jar. Let the yeast settle from the beer and pour off the top of your jar. Then top up with cooled preboiled water (so it doesn't oxygenate) and store in the fridge for 2-3 weeks tops.

[PEACOCKSUIT]

So how many spoon fulls oy yeasty sludge does it take to get a 23l batch of ale going then? Im thinking what is left at the bottom of a vessel is several spoon fulls.....

Do you need the whole lot?

Also I have always been told that dead yeast cells on the bottom of a FV once a beer has fermented can effect the taste if you leave it ontop for too long. If I scoop this stuff up to use to ferment a future batch, will I not be adding a lot of dead yeast cels to the beer as well as living ones, and will this not tarnish the taste at all?

Cheers.

[cwrwfawr]

Experts recommend that you pitch your wort with a concentration of 10,000,000 cells per milliliter. When you take yeast from the bottom of the fermenter you get a concentration of around 100,000,000 cells per milliliter, as this is the concentration reached when they stop reproducing and start making alcohol. Obviously you will have some deads ones in there so it will be a bit less than 100,000,000. So what you need to do is scale up that 100,000,000 per millilitre to 23 litres (Unfortunately I have a very nasty hangover and can't work that out this morning, maybe someone can help).

Also as HighHops suggested you can clean the yeast by placing it in a santised jar of cold water, let it settle and pour off the dark stuff(trub and dead yeast) at the top, top up with cold water and refigerate. I used to do this but it was a bit of a hassle so now I don't bother. And I would start with fresh yeast after four or five cycles.

Hope this helps

[cwrwfawr]

After thinking about it seems sensible to use about 10% of the slurry from a 23 litre batch to give you the required concentration for the new 23 litre batch. The issue is not to over pitch because you need the yeast to reproduce to get to the 100,000,000 concentration in order to get the lovely flavours from the yeast.

Having said all that, it's all a matter of personal/recipe prefernce. Under pitching could give you more esters, over pitching could give you a cleaner brew.

There are so many wonderfull variables to mess around with !!!!

[PEACOCKSUIT]

Brilliant, cheers. Recycling yeast will come in handy when I start brewing lagers/pilsners as you have to pitch so much.