Belgian Golden Ale Fermentation/Beersmith

[Jsbeckton]

I am taking a shot at Jamil's recipe from BCS, just scaling back to 3 gal. I will have a 1L WLP570 starter w/stirplate as recommended and a starting gravity of 1.072 (~75% Belgian pils and 25% beet sugar) mash at 148F and all seems well. However Beersmith predicts a FG of 1.001???

I am targeting 1.007 and think this will be tough to get to, so I have no idea where BS is getting 1.001 from? I plan to add the beet sugar during fermentation but even when I specify that it doesn't change anything.

Funny thing, if I remove the beet sugar from the recipe it predicts a FG of 1.007. I thought that beet sugar was 100% fermentable so I would think that adding it would increase the ABV but not the FG so I must be missing something.

Any thoughts?

 

[ZombieBrew83]

I'm fermenting the same recipe right now. IIRC Duvel (the classic BGSA) is fermented below 1.007. They also get something crazy like 93% AA from the yeast. I do not use beersmith but I would take their FG prediction with a grain of salt. The fermentation conditions (temp, O2 levels, time) will have a great impact on your FG.

Why did you target 1.007 specifically?

 

[Jsbeckton]

1.007 is the FG target listed in Jamil's book. Just seems strange that Beersmith is predicting something that low for these conditions?

 

[sherma]

1.007 is the FG target listed in Jamil's book. Just seems strange that Beersmith is predicting something that low for these conditions?

Weird. I just put that recipe in and got the same thing.

I played around with it and it is the sugar that is doing it. When I make the recipe start at 1.072 with all Pilsner malt, it has an FG of 1.017.

Still, it doesn't seem right to be at 1.001 with the sugar. I would email Brad. He's pretty good about responding and will get back to you.

 

[Jsbeckton]

I would email Brad. He's pretty good about responding and will get back to you.

Took your advise, will post any resolutions offered.

Thanks

 

[highgravitybacon]

That's a fair amount of sugar, so it's very possible that with a low mash temp (<149F) you may indeed ferment out that low especially if following the BCS ramped fermentation temp to finish at or above 80F. I have used Wyeast 1388 which is similar but not identical to WLP570 and it indeed does finish quite low. I foolishly used 1388 as a bottling yeast in a cider fermented with US-05. The US-05 stopped fermenting about about 1.001, however the 1388 continued to ferment even further. The cider went from very slightly sweet to dry as the desert in the bottle and was carbed a bit more than intended suggesting that 1388 found sugars to munch on that US-05 was too lazy to get to.

To give you some perspective, I used a similar recipe to that in BCS but dialed the sucrose back from 26% by weight to 15%. It resulted in a beer with a terminal gravity of 1.006 down from 1.074 for 91.8% apparent attenuation. Jamil is no fool when it comes to his recipes, and who am I to doubt them, but with my equipment and my recipe, I think that the 26% sugar was a bit on the high side.

One suggestion I found was to not think of the sugar as a percent weight of total grain, but rather as a percentage of total fermentables. Since sucrose is 100% fermentable, but most pils malts are ~78% fermentable, the total contribution of the sugar is much higher. I suspect that BeerSmith, which is a really nice program, is considering the total contribution of the sugar as fermentables and adjusting the theoretical finishing gravity accordingly. The software I use, Brewtarget, does not and the attenuation figures it provides are based exclusively on the yeast's published attenuation.

 

[sherma]

One suggestion I found was to not think of the sugar as a percent weight of total grain, but rather as a percentage of total fermentables. Since sucrose is 100% fermentable, but most pils malts are ~78% fermentable, the total contribution of the sugar is much higher.

Aha. I think you're on to something there.

 

[501irishred]

Got a response back from Brad about a similar situation concerning dextrose and lactose (highly fermentable to non fermentable, all treated as a standard 78%). These have been an issue since inception. His reply was that it is on his "to do" list. Non critical bugs have been temporarily put on the back burner while he has been investing most of his time recently on new products like the fully editable iPhone app. He mentioned he will be getting back to all the bug fixes "in a couple months", and that reply was mid January if I recall correctly. Then again, per the BS forum, the lactose issue was discovered and responded to by Brad (will fix in upcoming release) back in June of 2011. Fix upcoming? Aggravating, but all in all I still love the program......

 

[Jsbeckton]

One suggestion I found was to not think of the sugar as a percent weight of total grain, but rather as a percentage of total fermentables.

That's what I mean, the 100% fermentable sugar shouldn't impact the non-fermentable portion of the pilsner malt. That's what puzzles me, you would think any sugar addition would only impact ABV and not FG because the non-fermentable sugars remain unchanged.

 

[highgravitybacon]

That's what I mean, the 100% fermentable sugar shouldn't impact the non-fermentable portion of the pilsner malt. That's what puzzles me, you would think any sugar addition would only impact ABV and not FG because the non-fermentable sugars remain unchanged.

It will because alcohol is less dense than water.

 

[Jsbeckton]

Ok, heard back from Brad:

"Hi,
I made a modification to the program so it now takes into account sugars separately with a higher than average attenuation. The reason for this is that most sugars (including beet sugar) are almost 100% fermentable and ferment much more so than maltose. So that's why it is estimating a much lower FG with the sugar.
Cheers!"

So if Beersmith is just assuming that the sugar will be 100% fermentable that is no problem. Does this mean that Jamils recipe should contain more pilsner malt to return the goal of 1.007 FG after taking the sugar into account?

Seems that if this were the case there would have been many people saying they had a very low FG but I haven't seen that.