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A Question About Pitching Lager Yeast

Started by Dr Jacoby, May 13, 2013, 10:55:20 am

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Dr Jacoby

Yesterday I completed an epic Bohemian Pilsner brew. It involved preparing a big starter, conducting a step mash, boiling for close to 2 hours and then chilling the wort down to 8C (I was aiming for 5C but time was against me).

Everything went pretty well up to the last step - pitching the yeast. I had a 3.5 litre starter sitting in the fridge at 19C for two days. The morning of the brew I turned off the stir plate and started to chill it down to pitching temp. However, when I went to take the starter out of the fridge it was clear that most of the yeast had not settled. With time against me, I decided to pitch the whole thing, liquid included. I figured this wouldn't be too much of a problem since the starter was just a little weaker than the wort. But then it occurred to me that lager yeast creates quite a lot of diacetyl at temperatures over 13C, and the whole point of pitching lager yeast at a low initial temp is to reduce the precursors of diacetyl.

So my questions is, if you pitch a full lager starter (as opposed to just the yeast slurry) are you introducing a diacetyl bomb even if you chilled the starter down to less than 8C? Is it important with lager starters to only pitch the slurry?
Every little helps

Dr Jacoby

I had a full response written to this but it was lost when I tried to post it. The nub of what I said is that I definitely plan to do a diacetyl rest and extend the lagering time (probably longer than 6 weeks). But I'd still love to know for future reference whether it is crucial to dump the wort from a starter and just use the yeast slurry. 
Every little helps

Ciderhead

As tube says when you have fermented bump your temp up to 16-17 degrees for 2 days and then lager after that.
Of more concern to me is the stress you put on the yeast by pitching a 19 Degree C starter into 8 Degree wort, ideally temp should be the same or worse case scenario a differential of no more that 3-5 Degrees. Lager or Pilsners are bitches for manifesting and promoting off-flavours.
I use extra light DME for my larger starters and give the whole lot a got shake before addition.
http://www.homebrewtalk.com/wiki/index.php/Fermenting_Lagers

Dr Jacoby

Quote from: Ciderhead on May 13, 2013, 02:46:42 pmOf more concern to me is the stress you put on the yeast by pitching a 19 Degree C starter into 8 Degree wort, ideally temp should be the same or worse case scenario a differential of no more that 3-5 Degrees. http://www.homebrewtalk.com/wiki/index.php/Fermenting_Lagers


The yeast wasn't 19C when pitched, it was 8C, the same as the wort. I only ever use extra light DME for starters (when I choose not to use wort I have made myself).
Every little helps

Ciderhead

Quote from: Dr Jacoby on May 13, 2013, 03:32:33 pm
Quote from: Ciderhead on May 13, 2013, 02:46:42 pmOf more concern to me is the stress you put on the yeast by pitching a 19 Degree C starter into 8 Degree wort, ideally temp should be the same or worse case scenario a differential of no more that 3-5 Degrees. http://www.homebrewtalk.com/wiki/index.php/Fermenting_Lagers


The yeast wasn't 19C when pitched, it was 8C, the same as the wort. I only ever use extra light DME for starters (when I choose not to use wort I have made myself).


oops sorry missed the starter chilling bit
Anyways to answer your question pitch the whole lot in.

DEMPSEY

Looking here on this site that has good info on Lager brewing,
http://braukaiser.com/wiki/index.php?title=Fermenting_Lagers#Pitching_rate_and_yeast_propagation

This quote might be of interest,
QuoteIndustrial lager brewing only does cold pitching because the proper pitching rates and yeast health can be ensured. Because of the initially higher fermentation temperatures, warm pitching is associated with an increased level of ester, diacetyl and fusel alcohol production which are components that, at higher levels, are not desired in a lager. Diacetyl will be reduced by the yeast during the maturation of the beer but most of the esters and higher alcohols can carry over into the finished product.
Dei miscendarum discipulus
Forgive us our Hangovers as we forgive those who hangover against us

Ciderhead

Thanks Dempse I couldn't find that link I posted 6 months back

mr hoppy

Lager yeast tend not to settle to well which is one reason they are lagered in the first place. It probably not essential but I'd try to chill the starter down for a day or two before pitching. It won't settle out but you should definitely be able to decant off two thirds of the liquid without loosing too many yeasties.

Also, diacetyl is to style for BPs. :D

Dr Jacoby

I think I might make my lager starters well in advance in future and chill them for a few days to settle as much of the yeast as possible.

Incidentally, I was reading what Palmer has to say on all this and I came across something strange. He says that it is possible to "miss your opportunity for a diacetyl rest" (http://www.howtobrew.com/section1/chapter10-5.html).

What's this all about? Why can't you just wait until you are close to terminal gravity and then raise the temp up for a couple of days? Why is their a window within which you have to perform the rest? Is he wrong about this or is there something he has not explained?


Quote from: mr happy on May 13, 2013, 11:19:05 pmAlso, diacetyl is to style for BPs. :D


This is technically true but the levels we're talking about are very low; i.e. just above the threshold of what most people can perceive. For the homebrewer, I'd still say it's important to do everything possible to minimise diacetyl production in a lager. 

Every little helps

mr hoppy

I guess you've missed your window if you've racked the beer off the primary yeast cake. Otherwise, I'm not so sure. Some of what Palmer says about lagers, particularly lagering temperatures, is pretty off the wall.

Ciderhead

Slightly off topic here but you can also get diacetyl from infections, never had one, in my beer at least! thank god.

mr hoppy

From pediococcus. From memory, in lambic's the brett cleans it up.

Slightly less off topic, but I've read and think I've found in practice that you can also get diacetyl in lager if you ferment too cold, because the diacetyl precursors are still in the beer when it's packaged at which point they turn into diacetyl.

Dr Jacoby

Any book recommendations for lager brewing? I was thinking about getting New Brewing Lager by Greg Noonan but the reviews are mixed. Does Randy Mosher cover lager brewing in Radical Brewing? Any other suggestions?
Every little helps

mr hoppy

While Palmer and Noonan are definitely worth a read, Mosher and Radical Brewing have some good stuff on styles, the best lager brewing resources I've found are probably on the internet. The braukaiser website is very good on technique (a lot more practical for homebrewers than Noonan) and I found some of the Jamil Show / Can You Brew It podcasts (specifically Oktoberfest and Boh Pils) had some good stuff in between the banter.

MAF

Quote from: Dr Jacoby on May 13, 2013, 01:30:58 pm
I had a full response written to this but it was lost when I tried to post it. The nub of what I said is that I definitely plan to do a diacetyl rest and extend the lagering time (probably longer than 6 weeks). But I'd still love to know for future reference whether it is crucial to dump the wort from a starter and just use the yeast slurry.
I would say dump the wort and use the slurry. I never control a starter like I would a full batch of lager. And control is key when lager brewing.