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Efficiency-darker Beers Vs Lighter Beers

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Bidtfaun

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I have found over the course of several brews both light and dark, that my efficiency for darker beers is substantially less than with lighter beers.

I get around 80% for the lighter coloured beers, and around 72% for darker beers.

I speculate that it is related to water profile, which I don't make any adjustments to. Mashing temps are always correct relative to the body I am after depending on style, and I use a multi meter with thermocouple for accurate temp monitoring.

Generally mash until starch test is negative and fly sparge for at least 45 minutes and keeping an eye on SG (with refractometer) to avoid tannins and too low a preboil gravity.

Has anyone experienced this too?

thanks
 

MHB

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Well naturally if you use the same amount of grist you will get a slightly lower yield.
Most good base malts yield around 80% in the lab (0.8Kg of extract per 1Kg of malt).
Chocolate, Black, Roast, Carafa and the like generally yield just over 70%.
Without worrying about your particular brewhouse efficiency if you mashed 5Kg of pale malt with a yield of 80% and collected 25L of wort (ignoring losses) your OG would be 5*0.8=4Kg, 4/25*100=16oP or 1.064
If the grist was 10% Roast Barley with a yield of 70% (4.5*0.8)+(0.5*0.7)=3.95Kg, 3.95/25*100=5.8oP or 1.0632, but thats only a couple of percent lower and doesnt really account for the 8% you are talking about.
Remembering that Crustal and other Malts like Munich, Amber and Brown all have lower yields than Base Malt and its pretty easy to drop a few points of yield when you are making darker beer but I wouldnt be expecting a huge reduction.
Maybe you need to have a look at your mash pH, as darker worts tend to have a lower pH the extra dark malt might be pushing you out of bounds.
If the beer tastes good and you couldnt be arsed mucking around with the water chemistry you could just accept the lower yield and bump your grain bill up by the 8% you are losing (add more base malt) on a 5Kg grist you are only looking at adding 400g call it a dollar or two, give or take.
The pragmatist in me says just up the malt a bit, the other half would absolutely have to know why my yield was dropping.
Mark
 

QldKev

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Also the brewing software (assume you are using something) should take this grain bill into account.

Have you calibrated your thermometer, and check the mash pH?

QldKev
 

Bidtfaun

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ok so I have a couple of things to try-I don't at this point do any pH checking/adjusting so i might do that next dark batch (I guess I need something alkaline to bring it up to around the mid 5s-correct?)

in respect to calibration of my meter & thermocouple-no it has not been calibrated (however I have popped it into boiling water and noted readings that are in line with the temperature water boils at close to sea level -100degC)

I use BS1.4 and I know I don't use it to it's full capacity-not to worry-am still learning about AG brewing and it's intricacies.

thanks guys
 

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