OG five points too high...

[MizooBrew]

Like the title says: I brewed an AG Oktoberfest/Marzen on Saturday (recipe from Brewing Classic Styles), with an anticipated OG of 1.055 and anticipated FG of 1.015. I mashed slightly too high (only my forth AG brew, still having trouble getting my strike temps right), at ~154F instead of my desired 150F.

My grain bill:
5 lb Pilsner
4 lb Munich
3 lb Vienna
1 lb CaraMunich (60L)

My main question is how low of an FG can I hope for? I plan to ferment this at 50F with WLP820 (Oktoberfest/Marzen). This yeast is a notoriously slow fermenter, with somewhat low attenuation (65-73%). I pitched a starter that had been stepped up from one vial in 2L of wort twice, decanting both times. I was hoping to get this down near 1.015, as I plan to keg and serve this at an Oktoberfest celebration (come September). Any suggestions as to how low they would expect me to get? Perhaps I should raise my fermentation temp to 52F? Any help much appreciated.

 

[pericles]

Your higher OG is caused by greater-than-anticipated efficiency, not by (or not just by) your higher-than-anticipated mash temperature. The result is that you have two variables working against attenuation: extra sugars in the mash, and also extra unfermentable dextrines.

There are a couple of ways to goose the yeast into finishing low. The easiest is to rouse the fermenter (gently!) every few days in order to keep yeast in solution. You can also raise your fermentation temperature but, with a lager, you can't go too high without changing the character of the finished beer.

Another good option is to let the beer finish completely, and then pitch a dose of a better attenuating yeast like WLP001. It'll munch through whatever fermentable sugars remain in solution without impacting flavor noticeably, because it's only eating a couple of hundreths of a point worth of sugar. (WLP001 would also help chew through diacetyl, which can be a problem for lagers, so this is a good solution!) If you want to pursue this option, though, remember to pitch from a starter, because inactive yeast will not wake up if poured into an alcoholic, mostly fermented, beer.

One other option is to let the beer finish completely, carbonate, and then add sterile water to taste. To preserve the carbonic acid bite while you're sampling water additions, try adding measured amounts of selzer water to a measured glass until you're happy with it, and then size up the addition to fit your keg.

 

[jaysbrewing]

I just do the other option, I just add water.

 

[MizooBrew]

I was leaning towards pitching a higher attenuating yeast once fermentation is finished. Will adding water substantially impact the flavor? Seems like it would... If my OG was higher more due to greater efficiency than to extracting nonfermentables into solution, it would seem I might be able to get closer to my desired FG than possible. I'll keep an eye on it, and pitch another yeast once the first one gives out.

 

[tennesseean_87]

Your OG was higher because of greater extraction. Of the total sugars extracted, a higher percentage will be unfermentable than otherwise because you mashed high. When you mash, you aren't just extracting sugar--you're converting starch into sugar. what type of sugar (fermentable or non-) is affected by the temperature at which you mash, so you do have higher nonfermentable sugars than you would if you mashed at 150. You also have more total sugars, which is why pericles mentioned two variable working against you. How much of those fermentable sugars the yeast will actually eat is another variable, which you can manipulate with temperature, pitch rate, and yeast strain. This is probably way oversimplified, so feel free to correct me if you can.

 

[MizooBrew]

Thanks for the reply! I understand the issues associated with mashing at higher versus lower temperatures, I was more trying to get a potential estimate about what my FG might be with the parameters I described above. I expect it to not reach as low of an OG as I would desire due not only to the unfermentables now in my wort, but also because of the yeast strain I have chosen, which has low to medium attenuation.

With regard to a potential yeast strain I can use to clean up my lager at the end of fermentation, would using another yeast strain with high attenuation be somehow better than using a hybrid yeast like the WLP001 California Lager? I am currently leaning towards finishing it with WLP830 German Lager Yeast, which has attenuation of 74-79%, instead of the 65-73% for WLP820 Oktoberfest/Marzen. This is, of course, speculation at this point, but based upon my OG and the attenuation of this yeast I do not think it is likely to reach the level of attenuation I would like.

 

[biestie]

150 vs 154 isn't a huge difference. If I had to guess, you may be at most a couple of points high, barely perceivable. I'd leave well enough alone for now and see what you get. And as someone already suggested, let it finish out and if you end up a lot higher like the 1020 range, pitch a better attenuating yeast. If you're system's well calibrated, meaning that the temp you measured at 154 is in fact the actual temperature of the mash, you'll maybe be 1 or 2 points high, in which case, if it were me, I wouldn't mess with it.

The reason I mention system calibration, is because I was ALWAYS a couple points high when I first started all grain. I got to the point when if a recipe suggested 152, I'd mash at 148 as measured by my thermapen. Problem solved, dead nuts on ever since. Moral of that story is that 154 is just a number, it's really what you end up with in the end that matters, and that will vary from system to system.

The other thing I'll note is that stepping up in a 2L starter twice, is really only stepping up once. Another starter with the same volume and gravity does very little for you.

 

[tgmartin000]

Next time you can add water to your fermenter prior to pitching. Then you hit your og and you have more beer!

 

[MizooBrew]

:rockin:

Next time you can add water to your fermenter prior to pitching. Then you hit your og and you have more beer!

Totally should've done that. After some research and the responses to this thread it seems like I will probably be alright, and will likely only be a few points too high, if any. Another post made by an anxious homebrewer I suppose

 

[Buschbrew]

:rockin:

Totally should've done that. After some research and the responses to this thread it seems like I will probably be alright, and will likely only be a few points too high, if any. Another post made by an anxious homebrewer I suppose

I just had a similar issue and actually added water to my secondary. Were your volumes correct? At any rate. I scaled to get mine correct and everything turned out great. Instead of buying water, I just boiled a pot for ten minutes, let it cooled it to ferm temp then added it.

Cheers and good luck