Need some expert advice

[drobaina]

Still newbie on extract kits so bear with me. I am thinking of brewing a MWS Irish stout and using the S04 that comes with the kit. I was then planning on brewing their imperial stout and dumping it right onto the trub cake left behind by the Irish on the day that I rack it. Good idea?

 

[CA_Mouse]

This shouldn't be an issue, but be aware of the fact that you could be severely over-pitching the amount of yeast you need, especially if you are racking a 5 gallon batch onto another 5 gallon batch.

 

[boydster]

You only need about 1/4 of the yeast cake - maybe a little more if the new brew is a really high gravity. The rest you can dump or harvest & store in a sanitized jar.

 

[jimyson]

Don't pitch on top. Take the time to rinse it and pitch the proper amount of slurry after.

 

[flars]

Don't pitch on top. Take the time to rinse it and pitch the proper amount of slurry after.

I agree with this statement. I just tried the 'pitch a half cup or so of your slurry' method. Almost two days with no fermentation activity. I'm going back to the rinse method so I know how many milliliters of clean yeast I have.

In my opinion this is the only way to know your volume of viable yeast and if a starter will be needed for the next brew.

 

[eastoak]

I agree with this statement. I just tried the 'pitch a half cup or so of your slurry' method. Almost two days with no fermentation activity. I'm going back to the rinse method so I know how many milliliters of clean yeast I have.

In my opinion this is the only way to know your volume of viable yeast and if a starter will be needed for the next brew.

if you want to nerd out you could just count the yeast in the slurry. or not.

 

[flars]

if you want to nerd out you could just count the yeast in the slurry. or not.

I was going to do that, but ran out of dye to mark the dead yeast cells.

 

[BigFloyd]

Still newbie on extract kits so bear with me. I am thinking of brewing a MWS Irish stout and using the S04 that comes with the kit. I was then planning on brewing their imperial stout and dumping it right onto the trub cake left behind by the Irish on the day that I rack it. Good idea?

What's the planned OG of the imperial stout?

For a typical 1.050 to 1.060 second ale batch, you ought to either remove 75% of the yeast cake before dumping the new wort on top of it or harvest a cup of slurry and re-pitch that on the wort in a clean fermenter. If you're brewing the Midwest kit that's around 1.080, you may want to consider removing about half the yeast cake.

If it's a really big ale (like 1.100) or a high gravity lager (lagers need 2x the cells of ales), I'd rather first do a much lower ABV 5-gallon "session beer" and pitch on top of the cake from that (or harvest most of it and re-pitch) than go through the process of making a really big stepped-up yeast starter.

 

[drobaina]

The Irish is a 1.046. The imperial is a 1.086.

 

[jimyson]

The big thing here is to rinse out all of the crap that was left behind from the last batch.

 

[BigFloyd]

The big thing here is to rinse out all of the crap that was left behind from the last batch.

Not really.

You might want to take a look at this - https://www.homebrewtalk.com/f163/cold-hard-truth-about-rinsing-yeast-boiled-water-451925/

And this - http://woodlandbrew.blogspot.com/2012/12/yeast-washing-exposed.html "The hops and other partials did not separate from the yeast. So when you are throwing out the junk, it takes just about as much viable yeast with it as it takes debris."


I used to rinse harvested yeast slurry and store it under boiled/chilled water. I've become convinced that the practice wasn't as good an idea as I had initially been led to believe.

 

[eastoak]

The big thing here is to rinse out all of the crap that was left behind from the last batch.

all that rinsing might be rinsing IN even more crap from the air.

 

[jimyson]

Not really.

You might want to take a look at this - https://www.homebrewtalk.com/f163/cold-hard-truth-about-rinsing-yeast-boiled-water-451925/

And this - http://woodlandbrew.blogspot.com/2012/12/yeast-washing-exposed.html "The hops and other partials did not separate from the yeast. So when you are throwing out the junk, it takes just about as much viable yeast with it as it takes debris."


I used to rinse harvested yeast slurry and store it under boiled/chilled water. I've become convinced that the practice wasn't as good an idea as I had initially been led to believe.

My recommendation was not for storing the yeast, however it was to take the cake out of the fermenter that the OP was going to pitch directly on top of and rinse it out. If done correctly, you can still separate out junk from good stuff. Maybe not 100% but some is better than none. Otherwise, you are keeping the trub, dead cells, etc. in the next batch.

Yes, you are correct in that long term storage should use sterile water that is achieved from holding water to a temp of 250F for 15 minutes.

“The question many homebrewers have is, “How do I select only the best yeast if harvesting the entire contents of the fermentor?” The answer lies in yeast rinsing. While it cannot completely replace selecting the ideal yeast with a shovel, it can help separate out the trub, dead cells, and alcohol from your pitch.”

Excerpt From: Chris White with Jamil Zainasheff. “Yeast.” iBooks. https://itun.es/us/BbALQ.l

 

[jimyson]

all that rinsing might be rinsing IN even more crap from the air.

Sure, rinsing will increase the probability that contaminants will enter the slurry but I bet there are a whole lot of other processes that we do that allow some form of contaminants.

My point is not to rinse more than once or twice either so if you take care in doing so then things should work out perfectly.

 

[boydster]

My recommendation was not for storing the yeast, however it was to take the cake out of the fermenter that the OP was going to pitch directly on top of and rinse it out. If done correctly, you can still separate out junk from good stuff. Maybe not 100% but some is better than none. Otherwise, you are keeping the trub, dead cells, etc. in the next batch.

Yes, you are correct in that long term storage should use sterile water that is achieved from holding water to a temp of 250F for 15 minutes.

Both methods have their merits, which was covered pretty well near the end of the "Cold, hard truth" thread. It's really not that big of a deal to separate out the trub, though, because it has nutrients for the new yeast colony. Also, you can still separate a fairly good deal of dead cells and trub from the yeast cake without using boiled and cooled water - the green beer sitting on top of the cake works just fine for that. Swirl, wait, pour. The stuff that settles out first is the stuff you want to leave behind. Whatever is still left in suspension you keep, or at least enough of it to pitch into the next beer.

Or you could rinse it, like you describe, and if you are pitching right away then you probably won't have any issues, especially if you are using boiled and cooled water. The only practical difference between the two methods when you plan on repitching the yeast immediately is that one requires the boiling and cooling of rinse water, while the other doesn't.

 

[jimyson]

Good point.