National Homebrew Club Ireland

Brewing Discussions => Yeast Board => Topic started by: BrewDorg on January 10, 2017, 10:52:22 pm

Title: Repitch slurry or new starter
Post by: BrewDorg on January 10, 2017, 10:52:22 pm
Just kegged a 1.063 IPA and have collected a yeast cake of WLP007. I poured off as much beer as I could and scooped the cake at the bottom into an erlenmeyer flask with a sanitised spoon. I then added 500ml of boiled then cooled water and shook it up. I've never done this before, so I'm not sure this was the right thing to do.

This weekend I brew a 1.100 Russian Imperial Stout, 12.5L batch and I plan to use WLP007. Should I use the yeast I just collected or should I just make a starter from a vial I harvested already from a starter?

It seems like a waste of plenty of good yeast that I left behind. The IPA had a modest dry hop of ~50g so it's not too dirty. What is the best way of going about pitching this yeast cake if that's the best thing to do? Just looking for some opinions and advice thanks!
Title: Re: Repitch slurry or new starter
Post by: DEMPSEY on January 11, 2017, 12:06:34 am
Washed the yeast in 4 separate containers to help clean out the hops from the IPA. Brew your RIS then decant the wash from the top of each container  and pitch all the yeast leaving behind the dead gunk at the bottom  of each container. This yeast has already had one ferment which was like a big starter for your RIS. The second time around should have the yeast rearing to go.
Title: Re: Repitch slurry or new starter
Post by: molc on January 11, 2017, 08:41:24 am
I'd do it and not even wash. Normally I just pitch about 250ml into the next big brew, a calculator will give you the correct amount to use.
Title: Re: Repitch slurry or new starter
Post by: Bubbles on January 11, 2017, 08:50:15 am
I just pitch a portion of the yeast slurry. I haven't had any adverse effects over the years that would make me consider the pallaver of washing yeast.

If you're doing an RIS I'd consider pitching the entire cake. Very difficult to overpitch a beer style like that. I wouldn't expect any carryover of hop flavour in an RIS either.
Title: Re: Repitch slurry or new starter
Post by: neoanto on January 11, 2017, 10:46:28 am
Would pitching the entire cake not be a bit of overkill?
Seems a huge amount to be pitching!
Title: Re: Repitch slurry or new starter
Post by: Bubbles on January 11, 2017, 10:54:42 am
Quote from: neoanto on January 11, 2017, 10:46:28 am
Would pitching the entire cake not be a bit of overkill?
Seems a huge amount to be pitching!


It is in normal beers, but in an RIS (probably over 10%), I'd rather be overpitching than underpitching.

The biggest problem with overpitching is the loss of flavour development while the yeast is in a growth phase. But in an RIS (with lots of roast and malt flavours), I wouldn't consider a slight reduction in yeast flavours to be a massive issue.

But that's just what I do... ;)
Title: Re: Repitch slurry or new starter
Post by: DEMPSEY on January 11, 2017, 10:55:47 am
Maybe a little but look what he is pitching in to, a 1.100 gravity batch even if it is only 12.5 liters
Title: Re: Repitch slurry or new starter
Post by: BrewDorg on January 11, 2017, 11:03:47 am
Great stuff, thanks for the advice. Does the slurry above look typical and did I collect it ok? It was extremely compacted so I found it difficult to scoop into the narrow opening of my flask. I hope it is still sanitary. Even if my batch is only 12.5L, should I pitch the lot? That would be about 500ml of slurry?

The RIS will be above 10% for sure. I based the recipe on 65% but I have a sneaking feeling I will go beyond that. So either way I will have stronger wort or a larger volume of wort and therefore a need for more yeast  :)
Title: Re: Repitch slurry or new starter
Post by: DEMPSEY on January 11, 2017, 11:09:01 am
Learn to smell the yeast smell and use the smell test to see if its OK.
Title: Re: Repitch slurry or new starter
Post by: DEMPSEY on January 11, 2017, 11:10:46 am
Looks fine,fridge it to help it settle and when pitching,decant the top liquid and use the center portion.
Title: Re: Repitch slurry or new starter
Post by: BrewDorg on January 11, 2017, 11:19:36 am
I'm guessing it should smell similar to a healthy starter? I'll have a sniff  :D
Title: Re: Repitch slurry or new starter
Post by: Bubbles on January 11, 2017, 11:29:01 am
Quote from: BrewDorg on January 11, 2017, 11:03:47 am
Great stuff, thanks for the advice. Does the slurry above look typical and did I collect it ok? It was extremely compacted so I found it difficult to scoop into the narrow opening of my flask. I hope it is still sanitary. Even if my batch is only 12.5L, should I pitch the lot? That would be about 500ml of slurry?


That's a characteristic of a lot of English yeast strains. They settle like a hockey puck. :)

For a reduced volume, yes, I'd consider pitching a reduced volume of slurry, say 1/2 or 2/3. 500ml would be a lot alright.
Title: Re: Repitch slurry or new starter
Post by: BrewDorg on January 14, 2017, 10:40:23 am
So the yeast now looks like this. Compacted down to around the 250ml mark on my flask. Guess I'll decant and pitch it all later today.

Title: Re: Repitch slurry or new starter
Post by: Leann ull on January 14, 2017, 01:59:08 pm
That's loads, pour off as much of the beer as you can leaving 100ml to keep it fluid on a good shake, makes it easier to pour rather than it just glooping in.
There would also be trub on the bottom but it looks clean enough, smell ok?
Title: Re: Repitch slurry or new starter
Post by: BrewDorg on January 14, 2017, 02:12:39 pm
Smells hoppy but no weird or bad smell from it. Haven't decanted yet, I'll sniff it then too
Title: Re: Repitch slurry or new starter
Post by: Leann ull on January 14, 2017, 02:17:18 pm
Have a sip of the beer you pour off as well
Title: Re: Repitch slurry or new starter
Post by: DEMPSEY on January 14, 2017, 04:07:05 pm
Your new beer is 24 plato and your volume is 12.5 liters. To assume that your slurry is healthy it will have 0.8 to 2 billion cells per millilitres. Let's err and assume 1 billion cells. For ale a standard recommended amount of cells is 0.75 million per millilitres per  degree plato. The calculation is,
pitching rate x millilitre of wort x degree plato of wort =cells needed.
that's 750,000 X 12,500 X 24 = 225,000,000,000.
225 billion cells. So if we assumed you have 1 billion cells per millilitre in your slurry then you need 225 millilitres of slurry.
Title: Re: Repitch slurry or new starter
Post by: BrewDorg on January 14, 2017, 04:13:04 pm
Thought I'd smash the target but got a stuck mash so ended up missing it :(

1.095 OG so pitched all the slurry I had into it. Didn't taste the beer on top. Since I topped it up with 500ml water to begin with, I don't know if tasting that would have helped. The decanted slurry smelled fine though, mainly hops actually.
Title: Re: Repitch slurry or new starter
Post by: Leann ull on January 14, 2017, 07:48:08 pm
Stuck mash or sparge?, oat husks or a stir normally sorts that oak especially in bigger beers because of the weight of the grain
Title: Re: Repitch slurry or new starter
Post by: BrewDorg on January 14, 2017, 08:02:48 pm
Stuck mash. The overflow pipe is about 8cm from the grain bed and was being constantly used through the last part of the mash. I actually did a reiterated mash, the first part gravity  being spot on, the second part being 6 points low. I had rice hulls and all, just didn't bloody use them!
Title: Re: Repitch slurry or new starter
Post by: Leann ull on January 14, 2017, 08:11:20 pm
Ouch!
Title: Re: Repitch slurry or new starter
Post by: BrewDorg on January 14, 2017, 08:53:30 pm
I'll know in future. Rice hulls and mix the shite out of the mash a couple of times. Added some DME to hit my target so hopefully I'll still have my 10% stout next Christmas.
Title: Re: Repitch slurry or new starter
Post by: Leann ull on January 14, 2017, 09:11:16 pm
I know with oat you have to rinse not sure about the rice, might be no harm ?
Title: Re: Repitch slurry or new starter
Post by: BrewDorg on January 16, 2017, 10:47:58 am
Must rinse oat hulls is it?

The stout was off and running before I went to bed Saturday.
Title: Repitch slurry or new starter
Post by: Leann ull on January 16, 2017, 11:28:12 am
Yep, I chuck em in a bucket and pour through colander, easy to handle wet
Title: Re: Repitch slurry or new starter
Post by: BrewDorg on January 16, 2017, 12:34:31 pm
Good to know, cheers. I suppose that's why they tend to float so, because I usually don't soak them?