Reusing Fermentors And Yeast From Previous Fermentation - Question

[clarkey7]

Background:

I made an all grain Oatmeal Stout 18 L.

My Experiment:

I split the wort into 2 fermentors 9L of wort in each.
I added US05 dry yeast to one and WLP004 Irish Ale liquid yeast.

My Dilemma and Question:

I made a double batch of all grain Dark Ale which I will be chucking straight on to the yeast cakes (I just bottled them) to continue my experiment of these 2 different yeast cultures with the same wort.

As each of these fermentors will now be home to a full size batch......the wort level will be higher then the "scum line" from the previous fermentations (halfway up the wall of the fermentors).

I think I read somewhere that this "scum" should never be stirred or added back into the beer as crap beer (very harsh flavours) will result, but I'm pretty sure I also read that it is insoluble so my thinking goes:

As long as I don't muck with it - it shouldn't effect my brew.

Anyone?? :excl:

PS . I have been dreaming up ingenius ways of removing this "scum" in a sterile manner, but my brewer brain tells me it would be best not to play in the fermenter if I don't need to.

Is this a can of worms?

Thanks in advance,

PB :blink:

 

[peas_and_corn]

Yes.

Don't worry. Do you secondary? If so, then it'll settle out in the secondary and you won't have any problems.

 

[clarkey7]

No secondary....I just bottled.

I'm ready to tip in my dark ale wort now!

PB :chug:

 

[Zwickel]

...but my brewer brain tells me it would be best not to play in the fermenter if I don't need to.

congrats, you have a wise brewer brain

very often Im doing brews in a row, just put the wort into the used fermenter without any clean. So far those beers became my best ones.

Cheers :icon_cheers:

 

[clarkey7]

Thanks.....

OK. No major cases against at this stage..

I'm going for it.

PB

 

[Cracka]

Background:

I made an all grain Oatmeal Stout 18 L.

My Experiment:

I split the wort into 2 fermentors 9L of wort in each.
I added US05 dry yeast to one and WLP004 Irish Ale liquid yeast.

My Dilemma and Question:

I made a double batch of all grain Dark Ale which I will be chucking straight on to the yeast cakes (I just bottled them) to continue my experiment of these 2 different yeast cultures with the same wort.

As each of these fermentors will now be home to a full size batch......the wort level will be higher then the "scum line" from the previous fermentations (halfway up the wall of the fermentors).

I think I read somewhere that this "scum" should never be stirred or added back into the beer as crap beer (very harsh flavours) will result, but I'm pretty sure I also read that it is insoluble so my thinking goes:

As long as I don't muck with it - it shouldn't effect my brew.

Anyone?? :excl:

PS . I have been dreaming up ingenius ways of removing this "scum" in a sterile manner, but my brewer brain tells me it would be best not to play in the fermenter if I don't need to.

Is this a can of worms?

Thanks in advance,

PB :blink:

Or scoop out whats is required, wash fermenter, then add back in

 

[pint of lager]

I would do what Cracka suggested.

Transfer the yeast sediment to a sanitised jar, wash out the fermenter, you can even let it soak overnight, then make up your next brew and add a few dessertspoons of yeast to the fresh brew.

Be a devil try some of that brown scum, it won't hurt you but will help convince the brewer brain that clean fermenters are a good idea.

 

[brettprevans]

you dont need the whole yeastcake. I have a few times brewed something, bottle it then take a good few cups of trub (the crap at the bottom) into a sanatised jar, then wash fermentor and sanatise, drop new brew in and drop all of the collected trub into the fermentor. its a lazy way of doing it (ie not ashing the yeast as described above) but it works (so long as sanatisation practices are good). I have even used the trub from a dark ale/stout straight into a pale ale. worked a treat.

 

[pint of lager]

Best not to use the whole yeast cake. The brew will take off like a rocket. Fermentation generates a small amount of heat. Fast fermentation generates alot of heat which will make your brew too hot unless you have very good temp control in place.

Yeast washing is another step again which needs some specialised knowledge. Without access to a decent source of acid and the right gear, it is best avoided. Stick to a few fresh desertspoons of yeast from the bottom of the fermenter to kick off a new brew in a fresh fermenter.

 

[drsmurto]

Best not to use the whole yeast cake. The brew will take off like a rocket. Fermentation generates a small amount of heat. Fast fermentation generates alot of heat which will make your brew too hot unless you have very good temp control in place.

Yeast washing is another step again which needs some specialised knowledge. Without access to a decent source of acid and the right gear, it is best avoided. Stick to a few fresh desertspoons of yeast from the bottom of the fermenter to kick off a new brew in a fresh fermenter.

POL

I tend to collect the yeast cake from primary and wash it several times with sterile water making sure i separate the yeast from the cold break/trub etc. I then spilt that up and store that or dump it back into a fresh wort. Is this an OK practice? The yeast smells and tastes fine and is usually only in the fridge for a matter of 2-3 weeks. If its there any longer i wash a few more times and spilt it into 50mL vials and make starters from them.

Cheers
DrSmurto

 

[newguy]

Best not to use the whole yeast cake. The brew will take off like a rocket. Fermentation generates a small amount of heat. Fast fermentation generates alot of heat which will make your brew too hot unless you have very good temp control in place.

Yeast washing is another step again which needs some specialised knowledge. Without access to a decent source of acid and the right gear, it is best avoided. Stick to a few fresh desertspoons of yeast from the bottom of the fermenter to kick off a new brew in a fresh fermenter.

I pitch onto the yeast cake all the time - no problems at all. My beers turn out great, time after time. In my mind, removing the yeast, washing it, then pitching it is an unnecessary risk (infection).

 

[pint of lager]

POL

I tend to collect the yeast cake from primary and wash it several times with sterile water making sure i separate the yeast from the cold break/trub etc. I then spilt that up and store that or dump it back into a fresh wort. Is this an OK practice? The yeast smells and tastes fine and is usually only in the fridge for a matter of 2-3 weeks. If its there any longer i wash a few more times and spilt it into 50mL vials and make starters from them.

Sounds fine Dr Smurto. So long as a brewer understands the risks and has the knowledge to follow such a method, go for it. They need to follow very strict sanitary methods and need to understand the difference between sterile and sanitary. The smaller the volume of yeast, the higher the risk of having an infected batch. Am sure you already know this, just putting it in for any newer brewer.

 

[Interloper]

I pitch onto the yeast cake all the time - no problems at all.

What do you do about the scum/left over krausen residue? I have a Coopers Irish Stout that should be ready in about 7-10 days and I'm thinking of whacking a Porter straight onto it - any advice on avoiding the fairly thick scummage that the stout has left on the fermenter?

No fear pitching straight onto the full yeast cake?

As an aside, could I harvest yeast from the trub after 2 brews or would the yeast be thrashed?

 

[pint of lager]

I pitch onto the yeast cake all the time - no problems at all. My beers turn out great, time after time. In my mind, removing the yeast, washing it, then pitching it is an unnecessary risk (infection).

I agree, washing the yeast is an extra step that newer brewers should avoid. However, pitching onto a full yeastcake does have problems with heat generated. It obviously works for you, but does have a risk factor.

Reusing any yeast can lead to bad brews if there is an infection issue.

 

[newguy]

I agree, washing the yeast is an extra step that newer brewers should avoid. However, pitching onto a full yeastcake does have problems with heat generated. It obviously works for you, but does have a risk factor.

Heat isn't an issue in my basement except in the middle of summer, but that only lasts a couple of weeks. I also tend to pitch pretty cool, so I suppose that helps.

Reusing any yeast can lead to bad brews if there is an infection issue.

Absolutely, and that's why I only do 3 brews from a single pack of yeast. I could probably do more, but I'm leery about the infection risk. I suppose this also answers one of Interloper's questions.

Interloper, the scum is as close to insoluble as tar is. I don't worry about it and my beers turn out great. As long as the beer you racked off of the yeast is okay - no sourness, no phenols, no "funky" aromas/flavours, go ahead and pitch another batch directly onto it.

 

[floppinab]

What do you do about the scum/left over krausen residue? I have a Coopers Irish Stout that should be ready in about 7-10 days and I'm thinking of whacking a Porter straight onto it - any advice on avoiding the fairly thick scummage that the stout has left on the fermenter?

No fear pitching straight onto the full yeast cake?

As an aside, could I harvest yeast from the trub after 2 brews or would the yeast be thrashed?

Similar to original poster it all comes down to how good your sanitary practises are. If they hold up well there should be no problem throwing your next wort straight on top of the existing cake, the krausen line should cause you no problem at all. However, if you sanitary practises aren't quite there that krausen line is a great place for bacteria to get hold in the period between brews and infect the second brew. You need to keep the fermenter as sealed up as possible and minimise the time between draining and throwing in the next brew.

As some others have posted you don't need the whole cake, particularly for Ales, I would probably drain .....half... maybe a bit more of the trub to avoid a very quick ferment/krausen climbing out of your fermenter. For lagers, you can cold pitch on the whole cake, although again I usually drain off a fair whack of the trub as well.
That is pretty much what I do, also I tend make sure I start with lighter brews (say a pilsner) then pitch a darker brew as the second one (say a Bock) to avoid any effecting of colour from one brew to the next. In your case Stout to Porter should be OK.

Edit : forgot to answer your last question. Again as always, those sanitary practises are the key. The professionals will reuse......someone will correct me here........ 7/8/9 times. For home brewing yep I'd probably harvest from 2 brews without too much of a risk.

 

[Interloper]

Thanks for the responses, most helpful.

As for the smell of the Coopers Irish Stout no there are no funky aromas - it is nothing short of superb after 5 days. Ferment has slowed right down, still a few bubbles and when they burst they are deliciously fragrant.

My hygine is like an OCD housewife with a germ phobia so no probs there.

I guess after 2 brews I will be soaking the hell out of the fermenter as it will be way crusty.

I'll do the Porter to about 18/19L so it is at a lower level than the stout, but if it won't dissolve or 'screw the brew' I won't be too scared of the wort touching it.

I have a lager with Nottingham yeast in it alongside in another fermenter, so I reckon that will be the yeast I harvest for teh next few brews.

 

[newguy]

Edit : forgot to answer your last question. Again as always, those sanitary practises are the key. The professionals will reuse......someone will correct me here........ 7/8/9 times. For home brewing yep I'd probably harvest from 2 brews without too much of a risk.

A micro here reuses their yeast ~50x before reculturing from a fresh source. They "plate" each batch of beer (smear some on agar that's been treated with something that kills yeast) to see what grows. If anything grows, it has to be bacteria because of the yeast killing chemical (not sure what that chemical is). If the plate is fine, they harvest the yeast and set it aside for the next brew. They can harvest enough yeast from one batch for another 2 or 3, depending on how easily the harvesting operation goes.

They go ~5 repitches before acid washing the yeast. Every 15-20 repitches, they do a complete wash which involves another chemical which I can't remember that apparently selectively kills bacteria and not yeast.

 

[Interloper]

They can harvest enough yeast from one batch for another 2 or 3, depending on how easily the harvesting operation goes.

Fascinating. I love beer science

Any idea what the yeast is they do this with? Must be pretty robust.

 

[newguy]

Fascinating. I love beer science

Any idea what the yeast is they do this with? Must be pretty robust.

It's one of the Wyeast English strains, 1099 or 1098 for all their ales. Can't remember the exact strain. They also do this with one of the Wyeast lager strains for their lagers. Not sure what that strain is, though.

Their harvesting operation is anything but glamorous. A sanitised bucket with a length of sanitised twine and a squeegee stuck on the end of a 2m piece of plastic conduit. Messy.