Repitching a Yeast Cake

[Zephyr259]

I brewed 15L of dark mild with Wyeast 1728 Scottish Ale which started at 1.038 so I'm planning on using the slurry to ferment my bock/wee heavy hybrid which I'm brewing tonight and likely pitching in the morning. I have about a litre of the mild's slurry in a jar in the fridge and it's mostly solids so I'm not sure how much to pitch and the internet hadn't cleared it up much as I'm not sure if they are taking about washed slurry or the straight-from-the-fermenter stuff I have.

This beer is planned for 23L at 1.064-ish and going to ferment around 13c which is the bottom of the yeast's tolerance to make it most lager-like. So its going to need a pitch somewhere between an ale and lager.

Anyone got any advice? Is there an issue with just using it all? Thanks

 

[Drunkula]

I'd pitch the lot. Possibly let it settle in the fridge and then use a turkey baster to pull off the white yeast layer but I've done plenty of 'beer on beer' brews pouring wort straight on top of a previous ferment. I just taste the beer that comes out to see if it tastes off.

 

[MyQul]

I'm with drunkula on this. Just pitch loads. Simply because it's quite hard to over pitch at the home brew level (you should see some of the massive amounts advised to be pitched on American forums) but if you underpitch you risk a stuck brew.
I never bother with yeast calculators and just eye ball how much yeast I've got. After a while you get to know how much you need to get the job done

 

[lancon]

I think that reusing the whole cake is massively overpitching, and while it is better to over rather than underpitch both can put a strain on the yeast. Also using the whole amount means a build up of trub. I generally use a third of the yeast and I still think it is overpitching, generally FG a few points lower than it should, but I've been doing it like that for a few years, as above I smell the existing beer to check for any offness and always err on the side of caution.

 

[Clint]

I've only done it the once...I sterilised a cup and just scooped a few out and ripped them in the fv with the wort. It was away within the hour.

 

[Zephyr259]

Thanks guys, I had been planning on just pitching it all as the only "white" layer is just a slightly less dark brown an isn't much of the jar. I don't generally pitch this way preferring to overbuild starters but this was much more convenient this time.

 

[Zephyr259]

Wort cooled down to 13c by lunchtime today so I pitched the whole lot. I later used the jar to store some sanitiser and found that it's actually about 600ml not 1L. Still the same amount of yeast though I guess.

 

[lancon]

It would be interesting to know what the gravity finishes at, there are some blogs that have experimented with under and over pitching.

 

[rats_eyes]

I think you did the right thing there. If you're fermenting at a low temperature, your high pitching rate will be an advantage i would think. I've done this a few times by simply emptying a fermenter and pitching fresh wort directly on to the cake with decent results. Sounds like you've been more careful so hopefully this will be a success!

 

[Zephyr259]

I shall do my best to report back, should end up on my brew day thread also.

Thanks mate, figured that at twice the OG and being fermented almost as a lager the extra yeast wouldn't hurt. The main reason for the extra step was I knew I'd have to chill in the fridge before pitching as I can't hit 13c out of the CFC unless it's the depths of winter. Took 12 hrs to go from 23c to 13c. Also meant I didn't have to bottle on brew day.

 

[Llamaman]

My second brew I pitched the whole yeast cake of my first. It turned out fine, but it took off like a rocket and escaped the FV (and that's going some - it was a 12L brew in a 15L+ bucket). Fermenting at a cooler temp, hopefully you won't get the same problem. The only other time I did it, I repitched rinsed yeast that had been in the fridge a few weeks. As a result, it was far less lively and I didn't have the same blow off.

One thing I did the first time, which might not be best practise but worked for me, is that I transfered the yeast cake to a sterilised container, washed out the FV, then returned the cake to the FV before pouring the fresh wort on top. I did this to remove dried krausen from the FV and to rinse out the tap, which it occured to me were infection risks if left for repeated brews. I may be wrong.
You can also use this step as an opportunity to separate the yeast from most of the trub, if you feel the desire to do so (probably no need unless you repitch so many times you end up with tons of trub)

 

[Zephyr259]

Thanks for the information, I also had the FV totally cleaned between brews since I knew I'd want to chill the wort before pitching. Seems to be working fine, took a day to get going but part of that will be the cooler temp meaning CO2 is more soluble so it takes longer to start moving the airlock, that's my theory at least. Been chugging along nicely at 13c for a few days, much calmer than my usual brews which ferment at 20c. Started ramping up 0.5c per day as of Sunday.

 

[gar]

does this process work with dried yeast?
I'm about to bottle a stout that I used a sachet of Gervin ale yeast.
I'm planning to make another similar stout a few days later, and collecting and re-using the yeast would save a quid or so. I am very tight!
cheers

 

[Zephyr259]

does this process work with dried yeast?
I'm about to bottle a stout that I used a sachet of Gervin ale yeast.
I'm planning to make another similar stout a few days later, and collecting and re-using the yeast would save a quid or so. I am very tight!
cheers

Yeah will work fine, yeast is yeast once it's active. when I started doing 1 gal AG batches my first was a bitter using S-04 then I brewed a barleywine which got put right on top of the yeast in the demijohn, fermented fine with the proviso that it was my second batch as so it's a bit rough compared to what i brew now. Still have 8 bottles of the 10% fruitcake barleywine stashed away, wonder if a second year has smoothed it anymore.

 

[divrack]

does this process work with dried yeast?
I'm about to bottle a stout that I used a sachet of Gervin ale yeast.
I'm planning to make another similar stout a few days later, and collecting and re-using the yeast would save a quid or so. I am very tight!
cheers

I've done it a bunch of times and it works fine ish.
There is a school of thought that says you shouldn't due to something sciency in the process of making dried yeast and some such stuff I read somewhere from someone who seemed clever, but then hey. Beer wants to be beer.

 

[Zephyr259]

Oh I meant to say that you probably shouldn't use the whole yeast slurry if you're making a similar strength beer. My 2nd batch from the start of this thread was 1.5 time the volume at twice the OG.

 

[NIGHTSKY BREWING]

Have used that yeast ....it's certainly different .

 

[Zephyr259]

Have used that yeast ....it's certainly different .

Which yeast you referring to? There's been several mentioned, but I'm assuming the Gervin?

 

[Cwrw666]

I re-use dried yeast all the time. In Greg Hughes book it says you can't but he's wrong.
After bottling I collect about half a mug of yeast slurry and store that while I clean out the FV. I do no chill anyway and like to transfer hot to the FV for further sanitisation. After it's cooled pitch the mug of slurry.
Actually I've noticed the second batch usually finishes fermenting at a slightly higher FG, so maybe I'm underpitching a bit.
The beer is still perfectly fine though.

 

[Zephyr259]

Brew has gone from 1.070 to 1.025 in 2 weeks, odd given my 63c/72c step mash with 30 mins at each rest, maybe it's still going? Will check again in a couple of days.