Poor Mash Efficiency with BIAB and Wheat

[seilenos]

I'm closing in on around 50 BIAB batches and my mash efficiency is pretty consistent around 81% using a full volume/no sparge/squeeze method. The exception to this is when I have a wheat-heavy recipe. Observed mash efficiency drops to around 60%-65% if I am around 50% wheat.

All my grain is double-milled (either once at LHBS and once at home or twice at home).
I have my mill set very fine (0.030").

I do single infusion mashes for 60 min with mixing at 20/40/60 min.

I use brew'n water to calculate the appropriate additions for a pH of 5.4. (That being said, my pH meter broke a bunch of batches ago and I haven't replaced it.)

Short of assuming a crappy efficiency and adding additional wheat to the bill, is there anything obvious I am missing?

I can try a longer mash time but will have to deal with greater temp drop. I'm not sure if that would be a net gain or not.

 

[kh54s10]

I would try milling the wheat separately and inspecting the crush carefully. You may need to go tighter on the mill. Wheat is smaller and harder than barley. You might not be getting a good enough crush on the wheat.

 

[Griffin495]

Are you milling the wheat mixed in with the grain or doing them separately? I mill mine separately as they are a different size and have not noticed any difference in efficiency.

 

[seilenos]

I've been milling the grains together under the (possibly wrong) assumption that 0.030" is 0.030". I will certainly try separate grain bills for the wheat and double milling it finer the next wheat-heavy batch to see if that helps.

 

[Carolina_Matt]

I had a similar thing happen last week. I've only brewed about a half dozen BIAB so far, but my brewhouse efficiency has always been somewhere around 80%. I brewed a Blue Moon clone (6 lbs 2-row, 5 lbs White Wheat, 1 lb Flaked Oats) and my efficiency was awful. I think my OG was 1.044, rather than 1.050.

My first BIAB was this same recipe, direct (and milled) from Morebeer. I tried using my own ingredients this time, and the efficiency suffered. Next time I'll mill all of my ingredients separately instead of putting them together. I did notice that the mill wouldn't spin a few times, so something definitely seemed 'off' when I was milling. I use a Cereal Killer at the lowest mill setting (.025"). Live and learn.