91% Attenuation with Danstar Munich?!

I just bottled a batch of orange wheat which I was hoping would be a nice light, easy drinking summer beer, but...According to Beersmith I got 91.6% attenuation for an ABV of 6%! OG= 1.050 FG= 1.004. I checked my hydrometer and corrected for temps. Can anyone figure this out? Anyone else get similar results with Munich?


BeerSmith Recipe Printout - http://www.beersmith.com
Recipe: Orange Wheat
Brewer: Chance
Asst Brewer:
Style: American Wheat or Rye Beer
TYPE: Partial Mash
Taste: (35.0)

Recipe Specifications
--------------------------
Batch Size: 5.00 gal
Boil Size: 5.00 gal
Estimated OG: 1.046 SG
Estimated Color: 4.5 SRM
Estimated IBU: 18.2 IBU
Brewhouse Efficiency: 75.00 %
Boil Time: 60 Minutes

Ingredients:
------------
Amount Item Type % or IBU
1.00 lb Rice Hulls (0.0 SRM) Adjunct 11.11 %
5.00 lb White Wheat Malt (2.4 SRM) Grain 55.56 %
1.00 lb Caramel/Crystal Malt - 10L (10.0 SRM) Grain 11.11 %
1.00 lb Pale Malt (2 Row) US (2.0 SRM) Grain 11.11 %
0.50 lb Oats, Flaked (1.0 SRM) Grain 5.56 %
0.50 lb Wheat, Flaked (1.6 SRM) Grain 5.56 %
0.50 oz Tettnang [4.80 %] (60 min) Hops 8.6 IBU
0.50 oz Hallertauer [4.40 %] (30 min) Hops 6.0 IBU
0.50 oz Tettnang [4.50 %] (10 min) Hops 2.9 IBU
0.50 oz Hallertauer [4.40 %] (2 min) Hops 0.7 IBU


Mash Schedule: Single Infusion, Light Body, Batch Sparge
Total Grain Weight: 9.00 lb
----------------------------
Single Infusion, Light Body, Batch Sparge
Step Time Name Description Step Temp
60 min Mash In Add 11.25 qt of water at 161.4 F 150.0 F

Brew Notes:
Add 2oz fresh diced orange peel last 5min of boil. Add 1.5oz fresh orange peel last 4 days of primary.

My actual mash temp was 149F. Fermented at 70F for 7 days. Chilled to 58 for last 36 hours to clear it out some. Sample at bottling smells and tastes good. Some orange with a bit of banana...mmmm...

I haven't seen that kind of attenuation with that yeast, but I've never mashed a wheat at 149F. My last one was 155F and the attenuation was 71%.

I have been getting higher than normal attenuation as well, though with a number of Wyeasts.

Having done some research, I have come to the conclusion that the enzymes in my wort were continuing to break down sugars before I nuked them with the boil. I'm a stove top brewer and collect my wort into a bucket and then carefully laddle it into a pot (don't strike me down, HSA devotees!). I haven't been doing a mash out either. For example, I made Biermuncher's Cent Blonde and it finished at 1.004. Luckily, it's a light beer to start with.

I guess what I'm saying is that it may have been a process issue rather than a yeast issue. The yeast will do there thing based on how we treat them.

BTW: Nice looking recipe.

Mashing highly modified malts under 150F will produce a very fermentable wort. Did you do a mash out? If not, did you start heating your first runnings right away or wait until all the wort was collected? As Nugent mentioned, the enzymes will keep working and breaking the sugars down further and further until you raise the temp enough to denature them. A mash out will prevent this and "lock in" your wort profile. There was a recent thread here about crazy attenuation in a barleywine. Turns out the brewer did a partigyle brew without a mash out and the barleywine runnings sat for a couple of hours before he started boiling them.

I did do a mash out (hit 168), but now that I think about it my mash was probably about 90 minutes due to a slow runoff. I actually forgot the rice hulls so the mash was like paper pulp. I had to drain really slow to avoid getting stuck. Longer mash = more temp drop = more fermentables yea? Then again I've also heard the vast majority of conversion takes place in the first 30 minutes...so I'm not really sure. We'll see what happens next time I brew it and remember the rice hulls.

My understanding, though, is that the breaking down of longer chain sugars into simpler sugars continues to happen even after as much of the starch, that's going to be converted to maltose, has been converted. Once the enzymes go, or once the temperature drops too low, then the breakdown stops.

This is my understanding of it. Someone else probably knows more than I do, though.

RchanceN said:

I did do a mash out (hit 168), but now that I think about it my mash was probably about 90 minutes due to a slow runoff. I actually forgot the rice hulls so the mash was like paper pulp. I had to drain really slow to avoid getting stuck. Longer mash = more temp drop = more fermentables yea? Then again I've also heard the vast majority of conversion takes place in the first 30 minutes...so I'm not really sure. We'll see what happens next time I brew it and remember the rice hulls.

Click to expand...

If you did a mash-out and got the whole grainbed above 168 before draining, then a slow runnoff shouldn't have had any effect, as the enzymes would be dead. Maybe you're confusing the sparge with doing a mash-out? I personally don't do a mash-out, but I start heating my first runnings while I'm sparging to lock in the wort profile.

The vast majority of starches are broken down into sugars in the first 30 min of the mash, but the enzymes keep breaking the complex unfermentable sugars into simple fermentable sugars for as long as you let them. A longer mash will produce more fermentable wort even if you keep the temp constant the whole time.

Yea, you're right Juan. I double batch sparge and my sparges were at 168. So, sounds like my first runnings that go into the boil kettle are still converting complex to simple sugars.

Looks like a batch of amber ale I racked to secondary turned out a tad low on the FG as well. I've been doing everything I can indoors because it's so friggin hot out, but I guess I'll be moving it outdoors so I can start heating my first runnings also.

Thanks Nugent and Juan for helping me figure this out.

No worries. Your question was very timely and I only just figured the same problem out too. My technique has been identical to yours, hence the same problem.

Racked an extra pale ale to keg today - finished at 1.004. So it's 5.7% rather than 4.8%. Good thing it's really hoppy.

Good luck.