Is higher attenuation attainable with Belgian Ardennes?

[kds1398]

Started an AG Belgian Dark Strong Ale yesterday. I'm using Wyeast 3522 Belgian Ardennes which is has a rated attenuation of 72-76% & alcohol tolerance up to 12%.

My SG ended up @ 1.1004. I mashed @ 148 for 90 minutes, and I have 3 pounds of candi sugar (2 clear, 1 amber) for ~16% of the total sugar in the wort. Based on 74% attenuation that would only get me down to 1.027 FG, which isn't nearly as dry as I would like it for this beer. I'd prefer that it ends up somewhere around 1.008-1.015.

I've used some yeasts, Chico (American Ale, 1056) from Wyeast is a good example is rated @ attenuation of 73-77%... I've gotten 85-90% apparent attenuation out of it in the past fairly regularly, so I know the rated attenuation isn't to be trusted as an exact number to base your FG on. What has everyone's experience been with the Belgian Ardennes yeast? Attenuation higher/lower than rated? Does my range of 8-15 FG seem attainable?

I pitched @ 10pm last night... there is a full head of krausen to the top of my Better Bottle & it's bubbling like a demon as of 7am this morning. Seriously, like a machine gun of CO2 bubbles. It's gorgeous. I love watching the fermentation process. So turbulent & angry looking. I hope my 1/2 inch blow off tube can handle this fermentation without getting plugged causing an explosion. I did drop some fermcap S in this morning. Hopefully that helps a little bit.

Update: Checked the gravity. 1.019 right now. Fermentation might be done with 80-81% AA & 11% abv.

 

[kds1398]

Some additional info I didn't put in there @ the beginning.

I used 2 packs of the Ardennes yeast in a 2L stirplate starter with 1/4tsp. of Wyeast nutrient. I decanted the spent wort off after 24 hours & ended up with ~800ml of slurry (I wasn't too agressive with the decant). The slurry was extremely thick & even a bit chunky & it looked like it was full of tons of yeasties.

I added 1/2tsp of nutrient to the main wort 10 minutes before the end of the boil, and I aerated using pure O2 for 60 seconds with a wand/stone.

My ambient temperature is is ~60F in the basement where it is fermenting. Should I move it upstairs where it can be in the 67-70 range? The stick on thermometer is currently reading 65F... exothermic fermentation FTW.

Looked through other related threads, saw some some with 83-92% AA, which is pretty promising. Not sure what I should do about the temperature. Some of the ones with higher listed attenuation also mentioned that the beer hit temps in the mid 70s.

 

[SickTransitMundus]

Higher attenuation is always possible to some extent. I took a 1.090 Dark Strong to 1.012 with Ardennes (87% attenuation) earlier this year. Now I've got some brettanomyces chewing it down to 1.006.

Things that help - healthy starters, pure oxygen, and temperature control. You have two of those already. Never try to artificially cool a Belgian ferment - the yeast will stop dead and won't revive. I pitch my Belgians at 65F in a chest freezer, then I shut off the thermostat and let it heat up to whatever it wants to. After I get about 70% attenuation I put the carboy in a 75F closet until it hits final gravity. Rousing the yeast now and then helps.

60F is really cold for this yeast. I'd definitely move it upstairs and consider raising the temperature even further.

 

[kds1398]

Never try to artificially cool a Belgian ferment - the yeast will stop dead and won't revive. I pitch my Belgians at 65F in a chest freezer, then I shut off the thermostat and let it heat up to whatever it wants to. After I get about 70% attenuation I put the carboy in a 75F closet until it hits final gravity. Rousing the yeast now and then helps.

60F is really cold for this yeast. I'd definitely move it upstairs and consider raising the temperature even further.

When I get home I'll move it into my spare bedroom. It's at least 70 in there. Not sure of the exact temp until I measure it tonight.

 

[PaulHilgeman]

That yeast is a beast, depending on how much crystal malts etc. in there, I would definitely expect it to get down to 1.015 or less even.

It is practically a saison yeast in that it tastes good fermenting up into the low 80's. I have used that yeast several times, pitching at about 65 and letting it go on its own for about 4 days, it will get into the low 70's, then I actually heat it up into the high 70's while it finishes.

 

[kds1398]

I moved this one upstairs to the spare bedroom. Room temp has been between 70-72. Beer has been fermenting in the high 70s-low 80s. As the crazy initial fermentation starts to slow a bit the temp is dropping. I checked it this morning & it was at 77.

 

[SickTransitMundus]

If you want to get serious about Belgians (or if you already are), you should read Brew Like A Monk. I was leafing through my stained, dogeared copy last night and found a good discussion of how to increase attenuation.

Basically, yeast companies publish conservative attenuation ranges for all-malt grain bills. Wyeast lists Ardennes at 72-76% attenuation in a temperature range of 65-76F. The attenuation values likely came from multiple all-malt ferments in the middle of the temperature range. I don't know what saccharification temp Wyeast uses for their test batches, but I bet it's middle of the line, 152-154ish.

We already talked about temperature range. Beyond that, Belgians have a couple of attributes that help increase attenuation. Low saccharification temps (I shoot for 147F) and high non-malt sugar content. Both of these increase the amount of simple carbohydrates available and therefore push attenuation higher than the range published by Wyeast.

It would be grossly inappropriate for this style, but you can also increase attenuation by adding Beano to the ferment.

Aside from my Dark Strong I mentioned above, I also used Ardennes in a dubbel and tripel this year, each with 10% sugar in the grain bill. The tripel started at 1.082, the dubbel at 1.070. Both finished out at 1.008, with attenuations of 89% and 87% respectively.

 

[BrotherBock]

I am doing a Belgian Golden Strong. OG was 1.071 and its gone down to 1.010 in two weeks. I added my second sugar addition (bringng OG to 1.077) and the yeast got real excited.I'm expecting to get down to 1.010 at least. Which is 86%. Ardennes is great.

 

[beergolf]

The attenuation numbers for Belgian yeasts are usually very conservative. I routinely get higher. attenuation than predicted. I just bottled a BDSA that went from 1.097 to 1.010.

 

[PaulHilgeman]

I just took a 1.100 quad down to 1.011 in about 10 days with the Ardennes yeast. I starte it around 68 and peaked at 84 for the final 3 days. Smells and tastes amazing.

 

[BrotherBock]

So the BGS I just posted about was split between me and a friend. His half feremnted out to 1.004. 94% attentuation. Granted we had about 18% cane sugar. But that was intense. Mine is now aat 1.008. The only difference was his fermenter got up to 75 for the last 5 days of primary.

So yeah....higher attenuation is very attainable.