Beer ABV anomaly?

[coatesg]

Well, I'm sorry but my last 4 brews have all been 1052 to 1056 for 5.5 gallons from a 4.5kg MO grain bill, plus a bit of crystal or choc or black or whatever.

Really? You'd need 100% efficiency to do it with 4.5kg Pale. (Crystal helps a bit, but not enough to bring the efficiency down a lot). 4.5kg at 300 points per kg per litre, gives 1350 total points, which for 25L at 100% gives 1054. Beer Engine gives the same figures for me. If you're getting near 100% efficiency, then that's pretty darn good! The other option is that the current malt is giving much higher extract than 300p/l/kg).

Hydrometers at dawn, you cad.

[Brotherton Lad]

I don't think I'm fibbing, though I've just checked and the 1056 was from 4.8kg MO, the rest were 4.5kg. It's Simpson's MO from Barley Bottom, 90 min mash and a long slow fly sparge till the hydrometer says it's time to stop (after adjusting for temperature). I've found that I can get about 7 gallons pre-boil and not far off 6 gallon into the FV (overflow into a demi-john), so 5.5 gallon for the keg and bottles after accounting for dead space and trub at the bottom. I was surprised myself, but it's consistent and I'm not complaining. But you're probably right, it's the malt.

I don't bother with software, just empirical measurements.

[coatesg]

But you're probably right, it's the malt.

Yeah - the 300 figure is a longterm average I believe - and it'll vary around according to season and variety.

I don't bother with software, just empirical measurements.

And nothing wrong with that (though anomalies like this make it very hard to base a recipe on them!). Commercials will undoubtedly suffer the same problems - most will have to adjust the gravities uring the brewing process to get them in the right areas.

[Brotherton Lad]

Yes, I was saying earlier on this thread, a recipe is bound to err on the safe side, just so that it works and keeps people happy. It could be an anomaly, but looking back at my notes, I had the same results from my previous sack of MO, though that too was from the same source. Do you know what kind of relative change occurs year on year? I understand hops can vary greatly and everyone knows about wine vintages (2009 compared with 2008, for example).

I'm assuming most of us are brewing with 2009 malt (...just reminded me, when I was a boy in about 1970, my godfather was a HGV driver and used to take me on runs to Lincs to collect barley for the Associated British Maltsters' house in Pontefract, or maybe we were bringing malted barley back on second thoughts, I seem to remember a big warm dusty floor and malt shovels. And a Foden wagon, la, la, la.)

[Horatio]

so, how does a commericial brewery (of any size) accurately repeat each brew? It seems like it would (could) be quite variable given relatively small changes?

Most likely because they know their system inside out. With my old system, beforfe I upgraded to 10 gallons, I would consistantly get 88% mash efficiency. My new system is only returning 75% as I need to work on my new sparging set up. If I do everything the same way each time I brew I get the same OG and the same brewlength. I suppose they do it the same way each time and that ensures even results. And as Brotherton Lad says, they also have the option of liquoring back to adjust the OG/Brewlength.

This is only my opinion, someone will most likely correct me shortly.

[Spud395]

I was talking to a commercial brewer about this a few weeks ago.
He says it's down to knowing your system and repeating procedure.
But then every brew has to be measured extremly accutatly ( down to 2 decmil points) and duty paid on that.
It's in their interest to keep it right!