Adding new brew to old yeast cake

[JonGoku]

I am about ready to bottle my Scotch Ale and I have a Red Ale kit ready to go. My question is, what would the pro's and con's be of pouring my fresh brewed Red onto the yeast cake of the Scotch since they both use the same yeast?

I'm assuming the fresh yeast would be better then a dried yeast pack, but I'm curious about the trub that would be mixed in with the old yeast.

Cheers!

[brew captain]

This is a fairly common practice and can make good beer. Just remember that starting with a gigantic yeast population means that your yeast will not have to work as hard building up a sufficient population to consume the sugars in your wort. Less propagation generally means less flavor compounds so you won't get as much of the yeast's trademark flavor profile when you do this. Since dry yeasts have come a long way it is not safe to say that one would be better than the other. So far a trub goes, yes it can be a concern but I would not worry about it so long as you only intend to pour one batch on top of another just once. If you kept doing this over and over you would have a problem on your hands. Remember that trub contains important compounds that the yeasts need to thrive (fatty acids, or lipids to name one).

Personally I like to boil up a couple mason jars/lids and after transferring the beer from primary (save a pint or two) I will swirl the carboy and pour the slurry into the mason jars, trub and all (leaving the nastiest crub behind in the carboy as much as possible). This allows me to firstly clean and resanitize the carboy. Then, due to the effects of gravity the yeast slurry sediments (under refrigeration) with the yeast edding up mostly on top and the trub/hop bits from the previous batch settling mostly to the bottom of the jar. When I pitch to the next batch (within two-three weeks max after harvesting) I swirl the mason jar enough to get the top sediment in to suspension, but try not to disturb the bottom-most layers. Sometimes I just dump it all in too. Works like a charm!

[brahn]

Be prepared for it to take off like crazy and make sure you've got plenty of headspace in your fermenter.

[BrewMasterBrad]

I have done this before with no problems. I echo what Brent and El Capitan said. Another consideration is sanitation. If your first batch ends up infected, so will the second batch. The chances of that are small if you have good brewing practices. My procedure is similar to Brew Captain described. I would rather wash my yeast a little bit and ferment in a clean fermenter. It's more work, but I feel like I get better results that way. Also, your yeast population increases about 4x during fermentation. You do run the risk of overpitching and getting some funky or unexpected results.

[JonGoku]

Personally I like to boil up a couple mason jars/lids and after transferring the beer from primary (save a pint or two) I will swirl the carboy and pour the slurry into the mason jars, trub and all (leaving the nastiest crub behind in the carboy as much as possible). This allows me to firstly clean and resanitize the carboy. Then, due to the effects of gravity the yeast slurry sediments (under refrigeration) with the yeast edding up mostly on top and the trub/hop bits from the previous batch settling mostly to the bottom of the jar. When I pitch to the next batch (within two-three weeks max after harvesting) I swirl the mason jar enough to get the top sediment in to suspension, but try not to disturb the bottom-most layers. Sometimes I just dump it all in too. Works like a charm!

Thanks for the quick response and advice. I am undecided what I will do as I would like to have everything said and done in one session which has me leaning to just dumping in the new batch, however if I go with the yeast/trub transfer and re-sanitize method I have a few questions.
1) By "boiling some mason jars/lids" are you referring to sanitizing them, or are you talking about canning? I've never canned before so I'll have to read up on that to learn how.
2) I understand that under refrigeration flocculation occurs. How quickly does this happen and can it be sped up by putting in the freezer? The point would be to get this to occur fast enough to do in one session. I'm assuming though that this isn't possible and that refrigerating for at least a day may be required.

+1 to "Crub" nice combination of crud and trub.

[jward]

1) By "boiling some mason jars/lids" are you referring to sanitizing them, or are you talking about canning? I've never canned before so I'll have to read up on that to learn how.

I think he means boil to sanitize the jars to hold the harvested yeast. Canning wort can be fun too.

2) I understand that under refrigeration flocculation occurs. How quickly does this happen and can it be sped up by putting in the freezer? The point would be to get this to occur fast enough to do in one session. I'm assuming though that this isn't possible and that refrigerating for at least a day may be required.

Since the crub falls to the bottom quicker then yeast you can just pour the good stuff off of the top after a very short while. I would not refrigerate or put in the freezer any yeast I'd like to pitch right away.

[brahn]

2) I understand that under refrigeration flocculation occurs. How quickly does this happen and can it be sped up by putting in the freezer? The point would be to get this to occur fast enough to do in one session. I'm assuming though that this isn't possible and that refrigerating for at least a day may be required.

Freezing yeast isn't a good idea. In most cases, freezing = ice crystals = ruptured cell walls = dead yeast. I'm sure there are ways around this, but as a general rule I'd keep my non-dried yeast away from the freezer.

For doing it all in the same day, I'd suggest just pouring the new wort into the original fermenter. It's simpler and you've got fewer things to worry about sanitizing. That's not to say there aren't good reasons to go the other route, but for now and in this case, I'd go the simple route.

[JonGoku]

Since the crub falls to the bottom quicker then yeast you can just pour the good stuff off of the top after a very short while. I would not refrigerate or put in the freezer any yeast I'd like to pitch right away.

So if i swirl the crub and pour it into some sanitized container and wait 10-30min, the good yeast should still be in suspension and most of the baddies will be on the bottom? Or are you talking about pouring some of the top layer of sediment?

[BrewMasterBrad]

Since the crub falls to the bottom quicker then yeast you can just pour the good stuff off of the top after a very short while. I would not refrigerate or put in the freezer any yeast I'd like to pitch right away.

So if i swirl the crub and pour it into some sanitized container and wait 10-30min, the good yeast should still be in suspension and most of the baddies will be on the bottom? Or are you talking about pouring some of the top layer of sediment?

10 minutes would be a good wait time, 30 might be too long and most of the yeast you want you will settle out. Remember, you are selecting yeast by doiing this. If you wait too long you will be selecting the low flocculators and will end up with alot of yeast in suspension on your next batch.

As far as putting the yeast in the freezer - not a good idea. Like Brent said, you could kill it. Even if your intent is to on chill the yeast down and remove it before it freezes, you run the risk of forgetting about it and having an unitentional yeastsicle. Also, it is never a good idea to thermally shock the yeast with either hot or cold changes like that. The fridge is a more gentle way to cool them down.

[Rezzin]

Oh and in case you aren't using one yet - I highly recommend a blow off tube instead of a bubbler. You don't want to be cleaning your ceilings!

[JonGoku]

Oh and in case you aren't using one yet - I highly recommend a blow off tube instead of a bubbler. You don't want to be cleaning your ceilings!

Haha, did you say ceilings? I may look into investing into some tubing now if my ceilings are in harms way now.

A quick question on this topic; in my airlocks I use Shochu (Japanese Vodka) in case the fermentor inhales instead of exhaling. With a blow off tube in a small bucket, I'm assuming you'd never get enough suction from the fermentor cooling to draw up any liquid into the fermentor from the bucket correct? If so I will switch to sanitizer as I would hate to be charged with alcohol abuse.

[BrewMasterBrad]

Oh and in case you aren't using one yet - I highly recommend a blow off tube instead of a bubbler. You don't want to be cleaning your ceilings!

Haha, did you say ceilings? I may look into investing into some tubing now if my ceilings are in harms way now.

A quick question on this topic; in my airlocks I use Shochu (Japanese Vodka) in case the fermentor inhales instead of exhaling. With a blow off tube in a small bucket, I'm assuming you'd never get enough suction from the fermentor cooling to draw up any liquid into the fermentor from the bucket correct? If so I will switch to sanitizer as I would hate to be charged with alcohol abuse.

Either one will work. You only need enough to cover the end of the blowoff tube. I use a jar, like an old spaghetti sauce jar. If you put too much liquid in there, you can create too much head pressure and the yeast don't like that.

[JonGoku]

Either one will work. You only need enough to cover the end of the blowoff tube. I use a jar, like an old spaghetti sauce jar. If you put too much liquid in there, you can create too much head pressure and the yeast don't like that.

Gotcha, thanks.

[maltbarley]

If you put too much liquid in there, you can create too much head pressure and the yeast don't like that.

I've heard this before, but several respected breweries I've been into use a white plastic bucket with a very large tube going in about 12" of liquid. A full 6" high jar would be half the pressure. Either that's bunk or these breweries don't like healthy yeast.

[BrewMasterBrad]

If you put too much liquid in there, you can create too much head pressure and the yeast don't like that.

I've heard this before, but several respected breweries I've been into use a white plastic bucket with a very large tube going in about 12" of liquid. A full 6" high jar would be half the pressure. Either that's bunk or these breweries don't like healthy yeast.

There are also well respected breweries that ferment in open fermenters with no head pressure. I guess it may be depent on the yeast strain. Also, there may be a difference between the head pressure in a carboy versus a 15bbl+ fermenter.