Over Attenuation?

[arcaniment]

I just brewed an imp stout, and my FG was way low. Any ideas on what could cause this? I was using a new mash tun, and overcompensated for heat loss. My mash was around 155 instead of 152.

 

[Pappers_]

Hi and welcome to HBT.

Your higher than expected mash temperature would have the impact of increasing your final gravity (with more complex sugars in your wort). Lower mash temps = more fermentable wort; higher mash temps = less fermentable wort.

As for diagnosing the issue with your imperial stout, it would be helpful if you posted your recipe and process. Also, what did you base your expectations about the FG on - running the recipe through Beersmith?

 

[arcaniment]

sorry, I haven't had a chance to post in the last couple of days. My recipe was a kit from Midwest.

18 lbs. Domestic 2-Row barley
12 oz. Chocolate Malt
4 oz. Caramel 120°L
12 oz. Roasted Barley

3 oz Glacier @ 60 minutes
1 oz Willamette @ 2 minutes

White Labs British Ale 005. (Mr. Malty called for roughly a 4L starter. I did a 1.5 L starter, and pitched an extra vial).

Mashed @ 155, sparged @ 170

Boiled 60 minutes. 6.5 gallons starting, 5 gallons after the boil.

 

[aiptasia]

Tons of base malt, pico amounts of adjunct grains. The makings of a very dry tasting imperial stout. No wonder it over attenuated.

Raising the amounts of your adjunct malts and using a poorer attenuator like Windsor yeast might help with that "lack of malt depth and flavor issue you're missing.

 

[arcaniment]

Yeah, I noticed that when I sampled it. estimated F.G. per the kit was 1.022 - 1.035. My F.G. after 3 weeks was 1.012. The kit actually came with a packet of champagne yeast. It said to add it after 7 days. I've brewed plenty of beers in the 1.08 range, some of which I didn't even make a starter, and had no problem fully attenuating. Needless to say, I didn't add the champagne yeast. As I said, this was a kit I picked up from Midwest. What would you recommend to make it better?

 

[baldric]

Take some of the two row out. and substitute it with a character base like Maris Otter or Munich.
Replace some of the two-row with up to 3/4 lb of brown malt and 1/4 pound of Carafa.

Just sayin...

 

[cluckk]

As for overcompensating for heat loss, try something like Brew Smith. I've used it for a couple batches now and find that when I set everything right in the mash area I hit my temperature almost exactly.

 

[RM-MN]

Check the accuracy of your thermometer. You need very good accuracy for mashing and with that attenuation I suspect your thermometer is reading high so that your true mash temperature is nearer 148 than 155.