Wyeast 3944 Belgian Wit - Over attenuation?

[VampireSix]

Does anyone have any experience with Wyeast 3944 Belgian Wit attenuating way more than it is supposed to?

The Wyeast website says attenuation should be between 72-76%. However, a batch of Belgian Wit I did (Midwest Supplies Grand Cru extract kit) went from 1.070 to 1.009 over 3.5 weeks. That's 87%, right?

Fermentation temps were 63-65 ambient for the first two weeks, then 66-68 ambient for the last two weeks.

 

[GinSlinger]

Since this is extract, are we safe in assuming you topped off? Are you positive the wort and water were thoroughly mixed when you drew your sample?

I ask because the Midwest spec sheet on that kit lists an OG of 1.054-.058. You didn't mention adding a tone of fermentables. If you didn't, and since extract kits are usually very close to expected OGs, you're looking at an AA% of 83-4%, but more importantly not too far off of the predicted 1.012-1.010 expected FG. In my limited experience with 3944, 76% is too low, and 80ish is about right assuming there is sugar in the recipe (the 2 lbs of honey in the kit).

 

[VampireSix]

Midwest's OG listing is incorrect on many (most?) of their kits, and even inconsistent between what the outside of the box says and the instructions within. While the instructions provided with the kit list an OG of 54-58, like you mentioned, the outside of the box says 1.063. Putting the ingredients into The Beer Recipator (http://hbd.org/cgi-bin/recipator/recipator) gives an OG of 1.070 for 5.0 gallons with 65% steeping efficiency.

Yes, I mixed thoroughly after topping off. If I hadn't mixed properly, the gravity sample would have been lower, not higher, correct? If so, then the apparent attenuation would have been lower due to the lower perceived OG, meaning this isn't the problem.

And to the honey... you may have a point here. I didn't realize honey was 100% fermentable. With 6 lbs of DME and 2 lbs of honey, does the 87% apparent attenuation make sense?

 

[GinSlinger]

Not being thoroughly mixed will usually provide a lower OG, but not necessarily (it is possible for a higher density liquid to float on top a lower density one for a short period).

The honey is 100% fermentable, yes. That would be 25% sugar. I did a golden strong with 3944 and 20% sugar that hit 90% AA, so it's within reason.

Your FG is within range for a golden strong (or even Witbier), and your OG puts you in the BGSA territory. Unless it's undrinkably dry (and I can't see that happening, but it may be the case), you should look at this as a serious success as many people go to great difficulties to get the kind of attenuation you've got.

Finally, that WYeast number is low. WY3944 is the same as WLP400, which White Labs lists as 80-90%AA here: http://www.whitelabs.com/beer/belgianchart.pdf

 

[highgravitybacon]

The attenuation data on the website is not a real world number. It's only a way to compare one yeast to another. It's not the attenuation of your wort, it's the attenuation of their [Wyeast's] test specimen which is held consistent across yeasts.

The best use of that data is for understanding the starting point. When you throw a simple sugar, or a lower mash temp, into it you can pretty much assume that you can't assume anything.

Here's an example: wyeast 3711. Attenuation 77-83%. We know 83% attenuation puts it at the high end of the yeasts they offer. But in reality, my beer attenuation was >90% with 5% simple sugars, and people routinely report apparent attenuation approaching 100%. So the numbers are off, but not off for their intended use.

 

[VampireSix]

Alright, thank you GinSlinger! Your help is much appreciated.