@PeteB--When it gets to the U.S., let me know! Always looking to expand my whiskey horizons.
And I've never seen oil in my finished rye fermentations, but that doesn't mean it's not there.
Milling's effect on yield is significant, and I'll see if I can dig up a paper or two on it.
Enzymes (malt or concentrated) can only do so much, and if you're not exposing substrate to begin with, their effect (on yield) will be minimal to what they're supposed to do.
@Tom Lenerz
396.18 L at 40% abv- converted to proof gallons is 396.18L * (80p/100p) * (1gal/3.785L) = 83.7pgs., and is 7.92% abv for a 2000L fermentation.
For ferm efficiency, if calculated theoretical is 9% abv = 88.04% efficiency. I wish I could advise on whether or not this is good, but it's definitely not low, and if you're letting it ferment too long and oxidize, you may be reaching your peak earlier in the process, and losing EtOH to aldehydes.
@Greenfield
What is your cooker and/or fermenter density in terms of dry substance? This is a good number to know off the top of your head when it comes to yield.