partial-mash efficiency question

[drlars]

So I'm new to partial-mashing and I'm enamoured enough that I don't think I'll ever be going back to all-extract. I am doing BIAB-style mash with a sparge. 3-gal partial boils. I have a trappist dubbel clone in the secondary right now and a hefewiezen in my primary.

When I back-calculalted the my efficiency on the dubbel I was pleased to find that my efficiency was 80%. (I used the Brewer's Friend online program.) In retrospect, I should have known that it was one of those "too-good-to-be-true" things, because using that same 80% number for planning my hefeweizen left me coming up really short on my O.G.

Here are the two fermentable bills (both are 5-gal, and were mashed at 155-ish for 45 min then sparged at 170-ish for 10 min):

Dubbel: mash: 8 oz Special B, 8 oz Caramunich, 8 oz Belgian Aromatic,
2 oz Chocolate, 2 lbs pale rahr 6-row
other: 4 lbs Pilsen DME, 1 lb Amber DME, 8 oz cane sugar
1 lb Belgian Clear Candi Sugar
(O.G. was 1.074)

Hefe: mash: 2 lbs pale wheat, 2 lbs pale rahr 6-row
other: 3 lbs bavarian wheat DME, 1 lb honey
(O.G. was 1.044)

It was well-shaken in the fermenter before sampling, so that wasn't the error. By back-calculating it in the same way, my efficiency for the Hefe was only 35%! It even caused the estimated ABV (4.2%) to fall slightly below the style guidlines for a Hefe, which was sort of depressing.

The only thing I can come up with is that either a.) the wheat malt has some mashing requirements that elude me, or that b.) some of the malts in my dubbel (e.g. Caramunich, others?) had falsely raised my efficiency since they were pre-converted?

Can anyone more experienced weigh in?

 

[RM-MN]

Who crushed your malt? The quality of the crush seems to have a big impact on the amount of sugars that get converted and extracted (efficiency). With BIAB you can get away with a very fine crush/grind and not have problems with getting the wort separated from the grains and since the particles of grain are very small they get wetted quite well and it is easy to get the sugars extracted from them.

Wheat malt has smaller kernels than barley and no husk. The kernels are also harder so they don't crush as well. Several people have mentioned problems with efficiency when mashing wheat.

 

[aiptasia]

Wheat is also a water absorbing beast and i've had to squeeze the hell out of it to get all the liquid out, but that's neither here nor there. A finer crush on the wheat can help. Just pulse it a few times in an old food processor. You can definitely stand to use more base malt on the hefe. Now, a word of caution on honey. Honey is nearly 100% fermentable and it's sugars are favored by yeast over malt sugars. What this means is, if you add it to your beer before primary fermentation is complete, the yeast is going to eat it first before going for the malts. The end result is it tends to create extremely dry tasting beers with little or no residual honey flavor. To create the honey flavor, try using honey malt as an adjunct grain or add the honey after the krausen has fallen, then cold crash the beer after a few days to preserve some of the honey flavor and sweetness, or just back sweeten the beer with honey at bottling/kegging time to taste and use it to prime your CO2.

Your use of more adjunct grains in the Dubbel lend more unfermentable sugars to the wort (as does the amber DME), which has two effects: 1) A higher OG/FG and 2) Malt sweetness. This is to be expected in higher gravity Belgian styles so you're on target there. Don't expect great attenuation from your yeast on this beer.

 

[drlars]

Thanks for the rapid replies, fellas.

For the dubbel, I actually crushed the specialty grains myself at the LHBS. I know the mill there is adjustable, but I'm not savvy enough to change the setting that was on when I got there. I generally buy the specialty grains unmilled by the pound, since I'm typically using less than that for each batch, so I've got a bit of a collection now (stored in the fridge).
The 6-row (for both batches) and the wheat malt were purchased crushed from Midwest Supplies.

So you think I would need to go more than 50/50 on the 6-row/wheat ratio? Thats actually why I added the honey - to lighten it (while preserving EtOH%) since I thought that was a already a higher barley/wheat ratio than the DME (65% wheat). Yeah, I figured any honey taste would die in the primary. I am doing a Blonde next, and I'm using some Gambrinus specialty malt with that.

So you definitely think its the wheat and not the pre-conversion thing, huh? I guess it makes me feel better that others have efficiency issues with wheat as well.... still, 35% was horrifying, coming off of 80%.

So maybe in the future for Hefes, re-crush the wheat with a couple-three pulses in the Cuisinart to make it a little smaller crush?