Having said that mathematically it is not possible to get past the whole, entire, 100%,one
I was struggling with this concept too during the first unit of the brewing course at Ballarat University, untill the lecturer helped me figure it out.
Say you do a congress mash (which is a standard grain crush then laboratory mash) and get 100g/L sugar extracted. That is your set point for 100% efficiency, when compared to a congress mash.
A brewery running a mash tun setup performs their mash (coarser grind because a mash tun requires it), and gets 90g/L sugar extracted. Their mash tun efficiency is therefore 90% (compared to a congress mash)
A second brewery running a high pressure mash filter and hammer mill crushes their grain finer than the brewery using the mash tun, even finer than the laboratory does for the congress mash. So because of the finer grind and the mash filter they manage 110g/L extract. That's 110% extract compared to a congress mash.
The point is the congress mash does not indicate the absolute total amount of extractable sugars from the grain, it is just a standard by which everyone can compare. If you performed biochemical analysis on the malt for the congress mash to determine the total amount of potential extractable sugars, it might come back as 130g/L or 140g/L (actually starch because it hasn't been hydrolysed, but that's just complicating things).
At the risk of confusing the issue (ignore this if it does). Say a congress mash might extract 80% of the malt's weight in sugar, so:
From 1kg of malt, congress mash gives 800grams of extract
In the brewery you get 80% efficiency compared to the congress mash:
80% of the above 800grams = 640 grams from 1 kg malt
Another brewery might get 110% compared to the congress mash:
110% of the above 800grams = 880 grams from 1 kg malt
Notice both are below the 1kg of malt that was added.
So yes in brewing it is possible to get greater than 100% extract when compared to a congress mash. And the important part is
when compared to a congress mash.
Of course it's nonsense to say you can put in 1 kg of malt and get back 1.1kg of extract. Nobody is saying that.
James