Stepping up yeast starter/ Is it too late?

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PaulMcArthur
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Stepping up yeast starter/ Is it too late?

Post by PaulMcArthur » Thu Sep 21, 2017 2:11 pm

Hey all,
I'm pretty new to the world of yeast starters though i made one that's currently bubbling away happily in a milk stout.

My last brewday was cancelled and I'd made the 1L starter with WLP-001 on the Thursday morning in anticipation of brewing Saturday/Sunday with friends. On the following Monday night i took the starter off the stir plate, put clingfilm around the tinfoil lid/flask and popped the starter in the fridge to crash.

We're now brewing this Saturday so the flask has been in the fridge for 3 days and I'm planning on decanting the wort then feeding the yeast 2L of new DME wort, then cold crash again Friday night for Saturday's brew.

Is this too much stress for the yeast? Was 5 days on a stir plate as a 1L starter detrimental to them? With no way to measure their activity, I'm unsure if i should just start again!

Cheers,
Paul

PaulMcArthur
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Re: Stepping up yeast starter/ Is it too late?

Post by PaulMcArthur » Thu Sep 21, 2017 2:21 pm

I should add - the beer I'll be making (a pumpkin beer for next month's festivities) will be weighing in around 5.4%

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Kev888
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Re: Stepping up yeast starter/ Is it too late?

Post by Kev888 » Thu Sep 21, 2017 5:16 pm

I wouldn't start over again! The 'beer' in the starter may be quite oxidised after that long on the stir plate so pouring it off would be sensible, but the yeast will still be in reasonably good health provided the stir plate wasn't running excessively fast. Just give them some fresh wort and they'll do their stuff.

If the current starter isn't sufficiently large, there would be ample time to step up between now and Saturday's brew (provided the starter wort isn't too cold). You 'may' not have time for it to then settle out though; if so then you could consider pitching the whole starter.

Pitching the whole starter at 'high krausen' is a recognised technique, which is quite useful in such circumstances - some people even prefer it, since the already highly active yeast reduce lag time. If the starter has gone beyond high krausen you can wake it up again with some fresh wort on brew day - I take some wort from the boiler as early as possible to boil & cool it quickly in a saucepan for this purpose, whilst the main batch continues as normal.
Kev

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Re: Stepping up yeast starter/ Is it too late?

Post by PaulMcArthur » Thu Sep 21, 2017 5:56 pm

Phew! Thanks Kev, that's reassuring to hear - my stir plate gets fast enough to create a mini-vortex, but it's not excessively fast.

Does topping up with 2 litres of wort sound like a good idea? I guess that is just going to create 1 litre more of less-than-tasty wort which will be going into the final 5 gallon batch...

Good tips on using fresh wort from the boiler during the brew. I'll try that, hopefully they'll crash and settle overnight on Friday through to the end of the brew session on Saturday

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Kev888
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Re: Stepping up yeast starter/ Is it too late?

Post by Kev888 » Thu Sep 21, 2017 7:23 pm

There are two schools of thought; some people prefer to pitch very active yeast, others don't like to pitch the starter's beer/wort into the main batch.

My own take on it is that neither is a particular problem, in most cases. Starters are small and merely bland, not bad tasting (especially if you used wort and either a slow stir-plate or a non-stirred method) so they don't adversely affect flavour in most beer styles. On the other hand the extra lag from pitching healthy but settled yeast slurry may tax them a little more but is rarely large enough to cause concern in terms of infection or overall fermentation performance.

But certainly in situations where time is limited then pitching at high krausen is a very reasonable thing to do IMO. I'd certainly take this over delayed/late pitching or using some random dried sachets from the store cupboard.

If there is time you can achieve a kind of middle ground by letting the yeast settle and decanting the starter beer, then adding some fresh wort to wake them a bit somewhat prior to pitching. Drawing off wort early on brew day (and boiling + cooling it) for this purpose makes the starter closer to the intended batch, but sadly it was't my idea, I got it from Dennis King.
Kev

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Re: Stepping up yeast starter/ Is it too late?

Post by PaulMcArthur » Mon Sep 25, 2017 1:55 am

I did this and the yeast looked like it was working it's magic on the Friday pretty well - it was pretty vigorous and blew over the side of the flask with a heavy krausen.

I left it stirring until a couple of hours before pitching. The yeast actually settled pretty well on to the bottom of the flask so i decanted about half of the starter wort then pitched. It took a few hours but the fermentation kicked off fairly quickly and from the bubbling in the airlock, this seems to be the most vigorous fermentation I've had so far. Thanks for the advice!

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Re: Stepping up yeast starter/ Is it too late?

Post by Kev888 » Mon Sep 25, 2017 9:34 am

No worries, and I'm glad to hear it went so well.

Some strains can settle out quickly after finishing, and it sounds like this happened here so all well and good. For future reference, some strains can be more stubborn, and in those cases discarding starter-wort too soon would risk losing yeast and may also inadvertently select cells of certain characteristics for the brew (e.g. those which settled out quickest may include the more flocculant cells and also the less healthy ones too).
Kev

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