Help-my FG is too high!

[flaminpi3]

A couple of weeks ago I decided to brew an RIS with the following grain bill:

13# MO
1.25# Chocolate malt
1.25# Roasted Barley
1# Crystal 120L
1# Flaked Barley

I mashed at 153f (was shooting for 154) and was expecting an OG of 1.088. Well, it didn't go as expected and I ended up with a pathetic 50% eff and an OG of 1.060. The problem was a poor crush, as a large portion of the grain was not even cracked.

In anticipation of a higher gravity I built a 1 gallon starter of wyeast 1028. I went ahead and pitched the whole slurry expecting a quick and easy fermentation, but after six days it was only down to 1.022. After 8 days...1.022, so I stirred up the yeast and after 14 days...1.022.

I know I didn't underpitch, so what could be my problem? The only thing I can think of is that a lot of the grain was uncracked, so I had a much larger proportion of flaked barley being converted than intended. Would this contribute to a higher FG? Did I overpitch? I fermented at 65f.

 

[TipsyDragon]

my guess is you didn't get very much fermentable sugars in your wart because of the cracking. see what others say before making a decision.

 

[COLObrewer]

I think it is done, you have a bunch of crystal 120L in there which is mostly unfermentable, coupled with bad crush and semihigh mash temp. What did you use to calculate your expected FG?

 

[flaminpi3]

Ah, I see... so you're saying that with the same grain bill, the FG will be the same no matter what the efficiency/OG? I use beer tools to do my recipe calculations.

 

[Yooper]

Ah, I see... so you're saying that with the same grain bill, the FG will be the same no matter what the efficiency/OG? I use beer tools to do my recipe calculations.

Not really. The FG is a product of many factors- yeast strain and the attenuation from it, the temperature of the mash, the ingredients (some ingredients are less fermentable than others), etc.

So, if your yeast strain has an average attenuation of 68%, in a "normal" recipe, you would have had approximately 1.018 as a projected FG. However, since you used some crystal and roasted barley, that is a bit less fermentable. Simple sugars are nearly 100% fermentable, and leave less residual sweetness.

Since many factors go into the determination of the FG, software can only be so accurate in estimating the FG. My Beersmith software is usually pretty good with straight forward recipes, but when I use honey or lactose, the estimate is usually pretty far off.