Marris Otter efficiency problem??(all grain)

OK, I couldn't get Marris Otter last year so the shop subbed in Golden Promise. The GP has worked well and I've averaged 88% efficiency with my system and a thin mash 1.4qt/lb.

I brewed an old ale with Marris Otter grain and some wild hops yesterday, and at 85% efficiency, I should have hit 1.071. I got 1.052.

Has anyone else had this problem? I have a couple of bags of GP and one bag of MO, but I'm planning my strong scotch ale in AG for the first time (at home anyway) and would like to use the MO but am worried about the 65% effeciency I saw yesterday!! (actually planning a party guile)

Anyone experienced a lower efficiency with MO?

I've experienced it in recipes with non-malted grains, and attributed it to the lower diastatic power of Maris Otter. But I'd think the DP of MO would certainly be adequate to convert itself!

I've been using Munton's MO as the base for most of my beers and usually get around 80%. I've also used Munton's Pale Malt with no noticeable change.
Most English pale malts do have less diastic power than American 2-row pale malts but unless you are doing mashes with 50+% adjuncts then the diastic power of MO should be sufficient.
It is possible that the grain is slightly smaller than you were using, which would mean the crush was not as fine. This might cause an efficiency loss. Just a guess as i have not seen the difference.

Craig

I use MO for 80% of my beers and have not experience any issues. In fact, I brewed an APA on Friday using domestic 2-row and my efficiency went down 3-4%. The variance is nothing like what you experienced but it did go down. I attribute it to a faster sparge (I was a little impatient). Not sure what your mash technique is (fly or batch sparging) but if you do fly sparge, did you sparge quicker? And as CBBaron said, maybe your crush was different?

MO is smaller than other barley malt grains so it may be your crush isn't fine enough. I really crank down my mill when I use MO (0.036" gap) and have no problems with efficiency using it.

As the last three posters have noted, blame not the Maris Otter; look instead to your techniques.

Man, I gotta stop reading Tolkien.

Anyway, it's true. Start looking at what you're doing with the ingredient before looking at the ingredient. Chances are the ingredient isn't bad or off, per se; after all, Golden Promise is a UK malt, too.

If you can get a copy of the malt analyses for each malt from your supplier - or at least baseline, 'average' examples - compare them. You might find the difference right there. Let's look at two typical analyses from Briess.

The most important data from an analysis, in terms of extract yield, are Extract FG and Extract CG, both Dry Basis. FG = Fine Ground and CG = Coarse Ground. I like FG, because most of my grists are ground pretty fine. Comparing 2-row Brewer's Malt and 6-row Brewer's Malt (PDFs), we find that 2-row FG Extract is 80.5% and 6-row is 78.0%.

Another important datum is how plump is the corn. In our example PDFs, the 2-row Plump is 80% and the 6-row 75%. That translates into mill adjustment! You need a narrower mill gap to get the same crush on 6-row.

The list goes on. Google "malt analysis" for more information.

Cheers!

Bob