Timing And Temp For The Fermentation Of A Dortmunder Lager

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I have been a long time lurker in the forums and this is my first post! :unsure:

I have dortmunder export (JZ all grain recipe) that is currently fermenting at 12 degC (fridgemate) using S-189 yeast. I pitched cold (10 degC) using two packs from craft brewer which were re-hydrated in accordance with fermentis instructions and had a healthy fermentation 24 hours later.

My dilemma is I'm going away for a week when my fermentation will be at the two week mark. I can see that it is slowing down now after 9 days and from my previous experience reckon it will be 3/4s done soon.

Do I raise the temperature to 15 degC for a diacetyl rest/complete fermentation before I go away and leave it for a week while away at 15 degC or keep it at 12 degC for the week Im away and raise the temperature when I get back?



Im assuming that at 12degC after 3 weeks it will be completely fermented and the raising of the temperature may not have any impact.

Any opinions would be greatly valued.

 

[argon]

Mate... i'd leave it sit at your current temp of 12C for the extra week... all my lagers are set an forget for a minimum of 3 weeks although i do 'em at 9-10C... only do a d-rest if you taste a sample and think it needs it... and i reckon S-189 @ 12C you more than likely won't get and diacetyl anyway... but definately taste it before raising temps.

 

[unrealeous]

Welcome to the forums.

I'd also be quite comfortable leaving it another week at 12 degrees, and give a few days D rest when you get back. Because 12 degrees is quite cool - the yeast stays in good shape and lets it ferment out completely, so another week at 12 won't do it any harm at all.

 

[[email protected]]

Argon,

You mention that you ferment your lager at 9-10degC which is what I understood as fairly standard. The only reason I used 12 degC as this is what is fermentis' recommended temperature for S-189.

What is the difference between doing at 12 as opposed to 10 for the s-189? Will the taste profile be different?

 

[argon]

I think you'll not notice any difference between 9-10c or 12c. Just with my regime and my ferm fridge I'm more comfortable to ferment cooler and wait longer. I don't really 100% trust that my batch is actually at the temp the probe is telling me and always err on the cool side as a tolerance.

If any difference the cooler temps will be cleaner and crisper. But as you found from the website 12c is perfectly fine for s189. It'll come out nice.