How is this attenuation possible?

[ClemTiger0408]

I made a Belgian IPA with Wyeast 3944.

OG was 1.060, I used both a hydrometer and refractometer and got nearly the same results.

FG... I am cold crashing now but I took a sample and the refractometer said 6.4. When I plug this into various calculators that's an FG of 1.006.

How could this be possible? I've been struggling since I switched to mashing in a tun vs. BIAB with efficiency and have been getting around 68%. I've been home brewing for about 3 years now, so I think I have a pretty good idea how to measure gravities. My target was 1.066 and I hit 1.060. I just cannot imagine the yeast dropped it down to 1.006.

Any ideas? I did ramp to 71F after a few days at 64 to try to get some yeast character, but I still can't imagine that much attenuation.

 

[iijakii]

Well, let's start with the easiest of possibilities -- it's not that low. Have you tried measuring with your hydrometer? Refrac calculators arent perfect.

Next, are you sure the thermometer is accurate and you aren't mashing way too low? Have you had overattenuation problems on other brews?

 

[spittybug]

They really liked it? Sounds like a good session beer.....not!!!!!

 

[ClemTiger0408]

Well, let's start with the easiest of possibilities -- it's not that low. Have you tried measuring with your hydrometer? Refrac calculators arent perfect.

Next, are you sure the thermometer is accurate and you aren't mashing way too low? Have you had overattenuation problems on other brews?

Admittedly, my mash temp was low. It was about 149 when I was hoping for 152. Could that make THAT large of an impact?

I didn't want to take a full hydrometer sample until I actually keg, but usually my refractometer is reliable to a hydrometer (after using the formula).

I should mention I calibrated the refractometer before and after.

 

[specharka]

Well, let's start with the easiest of possibilities -- it's not that low. Have you tried measuring with your hydrometer? Refrac calculators arent perfect.

Next, are you sure the thermometer is accurate and you aren't mashing way too low? Have you had overattenuation problems on other brews?

+1

Refractometers are notoriously lousy gauges post-fermentation.

Aside from that, 90% AA is high, but not unheard of for a sacc yeast. I will be brewing a Belgian DIPA soon and I am expecting attenuation in the same range (BeerSmith gives me an expected FG of 1.008). Low mash, favorable yeast conditions, and the addition of candi sugar will all promote higher attenuation. Consider it a blessing.

 

[Calder]

Admittedly, my mash temp was low. It was about 149 when I was hoping for 152. Could that make THAT large of an impact?.

Yes it can. Did you use any simple sugar?

 

[Bosh]

Yeah 90% attenuation isn't THAT high, saison yeast can blow right past that.

 

[ClemTiger0408]

Yes it can. Did you use any simple sugar?

I used some dextrose, yes. But I did use Beersmith and it didn't anticipate this at all.

 

[Qhrumphf]

Say it with me, "digestible".

I like most of my Belgians (including the big guys, Dubbels, Tripels, even Quads/BDSAs) finishing around 1.008, with Saisons and the like closer to 1.002. Mashing low (if your thermometer was off, and 149 was actually 147, then especially, but even at 149), yes, that kind of attenuation is entirely possible. My massive Quad goes from 1.105 to 1.008.

Edit: Especially if you're using sugar (aforementioned Quad uses quite a bit), you can easily get attenuation in the +90% range.

 

[beergolf]

Say it with me, "digestible".

I also like my Belgians and Saisons to finish low.. Drinking a Saison with brett right now... finished at 1.000. perfect.

 

[chickypad]

Belgian yeast - check
low mash temp - check
simple sugar in the recipe - check

I'd be more worried if it didn't finsh that low.

 

[Calder]

I used some dextrose, yes. But I did use Beersmith and it didn't anticipate this at all.

Now go to BeerSmith and change all your malt for Lactose (unfermentable), to get the same OG. You will get the same FG as you did for this brew ......... You will never take any notice of what BeerSmith says for FG again.

Still not convinced? Now change all malts to simple sugars, and FG should still not change.

BeerSmith, and all other brewing programs as far as I know, just use a % factor on the OG for whatever attenuation they have input for that particular yeast to get the FG. It makes no account for fermentability of the ingredients or mash temperatures.

 

[Qhrumphf]

Now go to BeerSmith and change all your malt for Lactose (unfermentable), to get the same OG. You will get the same FG as you did for this brew ......... You will never take any notice of what BeerSmith says for FG again.

Still not convinced? Now change all malts to simple sugars, and FG should still not change.

BeerSmith, and all other brewing programs as far as I know, just use a % factor on the OG for whatever attenuation they have input for that particular yeast to get the FG. It makes no account for fermentability of the ingredients or mash temperatures.

Eh. It changes some for all those factors. Simple sugar does drive the OG down. But yes, when you add in sugars, BeerSmith gets much less more accurate. Same goes for the extremes of mash ranges. An all-malt wort in the 152-154 range, I find BeerSmith is dead on every time. Go <150 or >156, or add in any fermentable/unfermentable sugars, and it's a dice roll.

 

[beergolf]

Those FG estimates are just an estimate. Brewing software does a good job with some recipes, but Belgians and saisons are usually waaaayy off. Try putting in a recipe that uses a yeast like 3711. It will probably five you a FG of about 1.010.. Hahahahaha, 3711 will laugh as it goes way past that number and finishes near 1.000.

I don't use Beersmith but I have adjusted the attenuation of certain yeasts in my software and now the estimates are much closer.