Efficiency And Malt Potential

[Simon W]

I've been using the trail Beersmith and downloaded the Joe White grain list for it, but am a little confused.

I'll try not to confuse you:

I have beersmith set for Metric units, and the listing for JW pils potential says 1037, which ofcourse is gravity/pound/gallon, no problem there.
But what gallon does beersmith expect this potential figure to be? US or UK? I'd say US.

Beersmith gives me a pre-boil efficiency of 90.1% for 1.73Kg of JW pils and 0.16 JW dark crystal grain in 9L(2gal UK) This is worrying.

I sat down with pen, paper and a calculator and did it the old way(pre-PC), I get 90.2% efficiency figure for 1037 lb/gal US(very close to Beersmith).
But I get 75.1% with 1037 lb/gal UK, which is more realistic.

So, is it possible that the 1037 figure for JWpils is actually given in Imperial gallons and Beersmith assumes it's US gallons, therefore there's no conversion done?
(ie: 1 USgal / 1 UKgal = 0.833 x 1037(lb/UK gal) = 1030.8(lb/US gal)

If I plug 1045 into Beersmith (1UKgal / 1USgal = 1.2 x 1037 UK = 1045 US) it brings pre-boil down to a more realistic 75.9%

Or maybe I'm getting a staggering 91.2% efficiency? I doubt it.
Whats going on?

 

[sosman]

Don't sweat on it.

First of all a figure like 1037 is not PPG, if it was 37 it would be.

2nd it doesn't matter whether you use imperial or US units because the lb/gal in both systems is the same.

As for 90% efficiency great, that is achievable. I would add with the small batch size you used, your measurement accuracy probably means a real efficiency between 85% and 95%. And don't forget malt potential varies from batch to batch, adding further uncertainty to your figure.

The bottom line is, make good beer and make it consistently. If you are interested in some numbers, check out this:

http://brewiki.org/wiki/homebrew/attachmen...wHouseStats.pdf

 

[Simon W]

Hi sosman, thanks for the reply.

The 1.037 potential is the measured specific gravity per pound per gallon right?

Isn't a US gallon equal to 3.78L and Imperial equal to 4.54L? (6:5 ratio)
So sugar extracted from one pound(same in UK/US) of grain in an Imperial gallon would have the same quantity of sugars as one gallon US, but lower density and therefore lower specific gravity?

I'm more confused now! lol

Doesn't realy matter tho, you've pretty much answered my question, 90+ % efficiency pre-boil isn't unheard of. Cool, thanks.


Edit: cleaned up so more understandable.

I just found something that answers my question: One pound of white sugar in one US gallon is 1.045 SG, and in Imperial gallon is 1.037 SG, so the 1037 for JW pils is in US units.