Should I use this yeast starter?

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guypettigrew
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Should I use this yeast starter?

Post by guypettigrew » Thu Jan 11, 2018 11:03 am

On Monday I started some harvested WLP 007 in a litre of 1.040 malt extract. The yeast was harvested about 5 weeks ago, I collected about 200ml of slurry from the dump valve on the chronical fermenter. It was kept in the 'fridge in a 500ml container with beer covering it.

The starter took 24 hours before showing any signs of activity. It then formed a low Krausen and did all the things yeast is supposed to do. Now, 2 1/2 days later, the yeast has settled to the bottom of the flask, with fairly clear 'beer' above it. There's probably twice as much yeast now as when the harvested stuff went into the flask.

It smells good and fresh but the gravity of the 'beer' over the yeast is 1.028, brix of 7.0.

I've never checked the gravity before. Just decanted most of the liquid off the top and then pitched the yeast into the FV. It's always worked fine.

What do you think? Will this yeast be OK to use, or have I somehow selected out a very low attenuating strain?

Thanks.

Guy

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Meatymc
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Re: Should I use this yeast starter?

Post by Meatymc » Thu Jan 11, 2018 12:33 pm

Don't have the knowledge/expertise to comment on the high gravity reading but I can say my scavenged yeasts (using IPA's method) have all seemed to be underperforming 'krausen wise' (fairly inactive as you describe) but have ripped through all 3 brews I've used this method on. Never occurred to me to check the gravity to be honest.

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Re: Should I use this yeast starter?

Post by MTW » Thu Jan 11, 2018 12:48 pm

Short answer, if it really is 1.028, I wouldn't use it. If 200ml of slurry really did take 24 hrs to get going in a 1L starter, that isn't great either.

You quote brix; have you measured 1.028 with a hydrometer, or is that a refractometer reading, to which (if it is) I assume you've applied some adjustment for alcohol?
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guypettigrew
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Re: Should I use this yeast starter?

Post by guypettigrew » Thu Jan 11, 2018 1:18 pm

Ah, excellent point about the adjustment for alcohol. Ooops--forgot!

Adjusting it gives a gravity for the liquid in the flask of about 1.017-1.020. Sounds a bit better, doesn't it!

Guy

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Re: Should I use this yeast starter?

Post by MTW » Thu Jan 11, 2018 4:15 pm

Ok, well I wouldn't trust the refractometer at all at this point, personally. Maybe have a backup ready (even a dry sachet) and take a hydrometer reading of the spent 'beer' on brewday before pitching, and make a final call. It just seems odd that it took 24 hours (for so much yeast for 1L) to get going, even 5 weeks on - though that's not something I've done. I suppose it depends on how much of the slurry was actually yeast, but even so...

Hard to say from afar.
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Re: Should I use this yeast starter?

Post by McMullan » Thu Jan 11, 2018 5:49 pm

That doesn't sound right, not for WLP007. It should have gone lower than 1.017. 200ml is a shed load for 1L. There was probably more feeding than growing, selecting for a geriatric culture. Just like people, they give up and drop out sooner. Try using about 20ml of slurry next time. 'Less is more' when it comes to yeast starters. Forget the 'logic' of adding more. As long as the starter wort is aerated and not nutrient deficient, the yeast will multiply to produce a good culture to pitch.

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Re: Should I use this yeast starter?

Post by guypettigrew » Thu Jan 11, 2018 5:58 pm

Thanks for all the input.

The yeast starter was made up by boiling 115g of malt extract from the Malt Miller in 1L of water. It was boiled for 10 or so minutes so would have been less than a litre when it went into the flask. I didn't measure the volume or take its Brix/gravity (eejit!) which is why it wasn't really possible to properly adjust for the alcohol after the yeast had settled.

Today was brew day so either the yeast starter had to be used or it would have to be one of the emergency packs of dried yeast in the 'fridge.

When it was time to pitch the yeast the liquid was poured off it to be measured with a hydrometer. I'd decided that if the hydrometer gave too high a figure (1.015 or over) then the dried yeast would be used.

The reading was just below 1.010. Very happy with that, so the yeast was pitched.

Thanks again for all the replies.

Guy

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Re: Should I use this yeast starter?

Post by guypettigrew » Thu Jan 11, 2018 7:03 pm

McMullan wrote:
Thu Jan 11, 2018 5:49 pm
That doesn't sound right, not for WLP007. It should have gone lower than 1.017. 200ml is a shed load for 1L. There was probably more feeding than growing, selecting for a geriatric culture. Just like people, they give up and drop out sooner. Try using about 20ml of slurry next time. 'Less is more' when it comes to yeast starters. Forget the 'logic' of adding more. As long as the starter wort is aerated and not nutrient deficient, the yeast will multiply to produce a good culture to pitch.
Hi McM

Are you saying I should only use 20ml of slurry, regardless of how much I've collected? Or are you saying I should change my collection method to only get 20 ml?

Perhaps collecting from the dump valve earlier on when the fermentation's still very active and not much has settled in the cone?

Guy

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Re: Should I use this yeast starter?

Post by McMullan » Thu Jan 11, 2018 7:39 pm

Yes, about 20ml stored slurry should be plenty for a good 1L starter. It produces a 'younger', fitter culture. Better than can be bought, in terms of liquid yeasts. Professional Brewers repitch harvested yeast within a few days or so, or dump it and start afresh. That's kind of what 20ml here is, starting afresh. And it's much easier at home-brew scales. (Below 1.010 sounds more like it :wink: )

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Re: Should I use this yeast starter?

Post by guypettigrew » Thu Jan 11, 2018 8:42 pm

Apologies for being stupid, but still not clear.

I usually collect 200ml or so of 007 yeast from the dump valve in the chronical. It comes out of the 3/4" valve like toothpaste. 007 produces loads during fermentation and it settles out really well. Unlike 001, where collecting 50ml counts as a success.

It's then stored in the 'fridge under beer for a while. Should I just use 20ml of it for the starter and chuck the rest away?

Thanks

Guy

McMullan

Re: Should I use this yeast starter?

Post by McMullan » Thu Jan 11, 2018 9:02 pm

Or save the rest for later. Keep the jar full of beer, to minimise oxygen levels.

Edit: the first harvest is probably cleaner than subsequent ones, so I'd work from that one.

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Re: Should I use this yeast starter?

Post by guypettigrew » Thu Jan 11, 2018 9:16 pm

Thanks. Understand now.

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Re: Should I use this yeast starter?

Post by orlando » Fri Jan 12, 2018 8:21 am

An analogy that helped me to understand innoculation rates is to imagine 100 Sheep being put into a field that only has enough grass to sustain 50. All the Sheep can feed a little but none of them will get everything they need. Be gentle, it is just an analogy not an equivalent.

This is a salutary tale about the limitations of refractometers, use a hydrometer folks. OP could have easily thrown away a perfectly serviceable starter, well maybe not perfect, but the next one will be. :D
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Fermenting:
Conditioning:
Drinking: Southwold Again,

Up Next: John Barleycorn (Barley Wine)
Planning: Winter drinking Beer

guypettigrew
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Re: Should I use this yeast starter?

Post by guypettigrew » Sat Jan 13, 2018 6:08 pm

Sheep--OK, that makes sense in a weird kind of way.

As an update you'll be pleased to know the sheep settled down well in the fermenter and started emitting plenty of gaseous bubbles the morning after pitching (herding) them into the FV.

Guy

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Re: Should I use this yeast starter?

Post by orlando » Sat Jan 13, 2018 6:17 pm

guypettigrew wrote:
Sat Jan 13, 2018 6:08 pm
Sheep--OK, that makes sense in a weird kind of way.

As an update you'll be pleased to know the sheep settled down well in the fermenter and started emitting plenty of gaseous bubbles the morning after pitching (herding) them into the FV.

Guy

=D>
I am "The Little Red Brooster"

Fermenting:
Conditioning:
Drinking: Southwold Again,

Up Next: John Barleycorn (Barley Wine)
Planning: Winter drinking Beer

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