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I'm doing 6 lagers according to the Brulosophy Quick Lager method, where the temperature is raised to 65*F/18.3*C for the remainder of fermentation after attenuation has hit 50%. 2 of them have been at 65*F/18.3*C for 3 weeks, 2 at 65*F/18.3*C for 2 weeks, and 2 at 65*F/18.3*C for 1 week.

All 6 of these batches used the same yeast (Wyeast 2206 with 3, 1.6L yeast starters, initially fermented at 50*F/10*C), used the same hops, had the same OG (1.050), and had the same mash temperature of 156*F/68.9*C (Single infusion). The only difference was the grain bill.

I've taken tons of gravity readings with one of those expensive final gravity hydrometers that is calibrated very well. The first 4 batches appeared to hit their terminal gravity of 1.0175-1.0215 on the 7th to 10th day at 65*F. The last two batches are undergoing their 7th day tomorrow and are also hovering in that range. It appears that the batches with the most Weyerman Munich II malt tend to have higher FGs (the one exception is the 95% Munich/5% Carafa Special II has a figer FG than the 100% Munich).

These are the highest FGs I've ever had from a 1.050 OG. I've never used Wyeast 2206, but its attenuation rate is 73-77% and my FGs don't reach it. I'm wondering if this high FG is due to me messing up the Lager schedule or higher mash temperatures.

Edit for those who are curious:

Batch # 1:

66% Pilsener 
33% Munich 
("Final" FG = 1.0165)

Batch # 2:

33% Pilsener
66% Munich 
("Final" FG = 1.0200)

Batch # 3:

100% Munich 
("Probably Final" FG = 1.0210)

Batch # 4:

95% Munich 
5% Carafaspecial II 
("Probably Final" FG = 1.0215)

Batch # 5: Oktoberfest 

38.46% Pilsener
30.77% Munich
23.07% Vienna
7.69% Caramunich
("Current and not final" FG = 1.0200)

Batch # 6: Vienna

29.50% Pilsener
26.03% Munich
43.38% Vienna
1.08% Carafaspecial II
("Current and not final" FG = 1.0195)
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  • I assume you mean 156°F? 166° is way too high to be useful for single-infusion mashing.
    – Franklin P Combs
    Apr 4, 2015 at 22:39
  • @FranklinPCombs yes 156; edited.
    – Matthew Moisen
    Apr 4, 2015 at 22:55
  • Out of curiosity, do you usually mash at 156°? One tricky part about the question is that you're asking if mash temperature alone can account for the difference (it can), but you're also observing this across six beers with (presumably) six different malt bills, each of which will produce its own particular spectrum of sugars. It seems like this experiment may be better suited to show the effect of the choice of malts on fermentability, since mashing temperature is the same across the board.
    – Franklin P Combs
    Apr 5, 2015 at 17:39
  • @FranklinPCombs I started all grain 20 batches ago; the first 14 were all ales at 148 or 154, none with Munich malt and only 4 with Pilsener malt; all FGs were appropriate. These 6 were my first 156. I added my malt bills for each batch to the OP.
    – Matthew Moisen
    Apr 6, 2015 at 2:38
  • @FranklinPCombs the original intention of this experiment was to teach me the subjective tastes of the "lager grains" used in different proportions. However it turns it could have another use! Based on your experience, do my grain bills and FGs make sense to you?
    – Matthew Moisen
    Apr 6, 2015 at 2:47

2 Answers 2

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I think there are two things to consider here:

  • Mashing temperature: at higher temperatures you will have increasingly less β-amylase activity, even with high diastatic-power malt, and this will favor production of non-fermentable dextrins and hence increase the FG (at 156° you'll have basically no β-amylase activity); and
  • High proportions of Munich malt: The higher kilning temperatures (up to ~220°F) during malting destroy much of the enzymes and leave the finished malt with far less diastatic power (less able to self-convert starches) than a pale or pilsner malt would have.

Even though Weyermann explicitly says you can use either Munich I or II for "up to 100%", you really can't expect too much fermentability from these malts, given the tendency for enzyme destruction during malt kilning.

You could try mashing lower and/or longer with high %s of Munich, but the reality is that there's a limit for what you can get from them in terms of attenuation limit.

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7
  • (I used Munich II from Weyermann). Would it also make sense that the 95% Munich 5% Carafa Special II has a higher FG than the 100% Munich I made (if we assume I held all other variables equal), given that Carafa Special II is kilned at an even higher rate than Munich?
    – Matthew Moisen
    Apr 5, 2015 at 0:10
  • Sure though not strictly because of diastatic power. Carafa and other roasted malts contribute extract (like any malt) but very little of it will be fermentable (see some discussion of this here). So that will impact your FG as well.
    – Franklin P Combs
    Apr 5, 2015 at 14:37
  • "but the reality is that there's a limit for what you can get from [Munich malts] in terms of attenuation". Let's say in the future I try another Munich Dunkel, mashing at 148 for 90 minutes. What type of OG would I be looking at?
    – Matthew Moisen
    Apr 6, 2015 at 5:24
  • @MatthewMoisen Did you mash the batches above for 90 min? I would expect you get the same OG, but with more fermentable sugars in the mix. Your FG should be lower, although perhaps not much due to the kilning of the Munich malt. Nice experiments by the way. Are all those 5 gallon batches?
    – Cleber Goncalves
    Apr 9, 2015 at 19:30
  • @CleberGoncalves I only mashed for 60 minutes. After I drink all this beer I might retry this with 90 minutes. Yep these are all 5 gallons.
    – Matthew Moisen
    Apr 9, 2015 at 20:09
3

Yes, a higher mash temperature absolutely leads to a higher final gravity. Mash temperatures in the 154-158°F promote the conversion of unfermentable sugars.

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  • Incidentally to the question and answer, do you think an OG of 1.020 (from an FG of 1.050) could be justified alone through a 156*F mash?
    – Matthew Moisen
    Apr 5, 2015 at 0:13

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