Reasons For Low Effeciency

[SJW]

Would there be any reason why I only hit 67% eff. with this grist? The grist was very well cracked, I only mashed for 60mins and I mashed at 69 deg C. I just wondered if the was any obvious reason why the eff. was so low when I did everything the same as I always do. Its fermenting like a run away train at the moment.


64 Stout
Foreign Extra Stout


Type: All Grain
Date: 21/04/2010
Batch Size: 25.00 L
Brewer: Stephen Wright
Boil Size: 32.05 L Asst Brewer:
Boil Time: 75 min Equipment: Keg Beer
Taste Rating(out of 50): 0.0 Brewhouse Efficiency: 67.00
Taste Notes:

Ingredients

Amount Item Type % or IBU
5000.00 gm Pale Malt, Ale (Barrett Burston) (5.9 EBC) Grain 76.34 %
500.00 gm Barley, Flaked (Thomas Fawcett) (3.9 EBC) Grain 7.63 %
400.00 gm Black Malt (Thomas Fawcett) (1300.2 EBC) Grain 6.11 %
250.00 gm Crystal Malt - Dark (Thomas Fawcett) (350.0 EBC) Grain 3.82 %
200.00 gm Carafa Special II (Weyermann) (817.6 EBC) Grain 3.05 %
200.00 gm Chocolate Malt (Thomas Fawcett) (1000.8 EBC) Grain 3.05 %
20.00 gm Target [11.00 %] (60 min) Hops 21.6 IBU
40.00 gm Fuggles [5.70 %] (45 min) Hops 20.6 IBU
0.50 items Whirlfloc Tablet (Boil 15.0 min) Misc
11.00 gm PH 5.2 Stabilizer (Mash 60.0 min) Misc
1 Pkgs Nottingham (Danstar #-) Yeast-Ale

 

[bconnery]

I'm not an expert on the stabilizer, I just use the stuff, but perhaps the combination of this and a large amount of dark grain, which helps with PH adjustment already, caused the water PH to be a problem?
I can't say for sure though, my water chemistry is limited to using ph5.2, but I don't do it for dark beers based on the assumption that dark grains help with PH adjustment.

Also, not sure about your equipment but did you formulate for a certain volume and end up witha little more at the end?

 

[Cortez The Killer]

I find I get a few more points with darker malts

The darker malts do change pH a bit

Have you had the same issue with other stouts / porters?

 

[///]

pH, mash management and grist can have an effect. Also in some camps, mid 60's is not that low!

Scotty

 

[SJW]

Thanks guys. I am not that worried, just that I always hit 75% - 80% but I normally do a 90 min mash. Maybe the PH was out? My other Porters and Stouts are all 75% at least. Anyway at least I shot for a high OG anyway, 1.054 is still a good winter warmer.

Steve

 

[warrenlw63]

Steve

Another thing you can do to counteract the pH change thing is to add your roasted malts at the mashout. Then the bulk of the mash converts in a regular fashion.

That said I've never seen much in terms of efficiency drop when roasted malts are added to the mash for the complete duration either.

Warren -

 

[Sammus]

I consistently get 65-70% for some reason, no matter what the grist is. I have tried all sorts of things - ph adjustments, what chemistry stuff, fly sparging, herms, started with braid, went to a false bottom, different mash in ratios, use several different thermometers to reduce the chance of temp error, different temperature and length mashes, step mashes, etc... The only thing I can think of that I haven't varied (Which is out of my control) is my grain crack, which is done at my LHBS by MHB, and everyone else seems to get great results with it so I'm assuming thats not it either...I've just learned to live with it

 

[TidalPete]

Steve

Another thing you can do to counteract the pH change thing is to add your roasted malts at the mashout. Then the bulk of the mash converts in a regular fashion.

That said I've never seen much in terms of efficiency drop when roasted malts are added to the mash for the complete duration either.

Warren -

I might try that Warren.
Put down an Oatmeal Stout last Friday & finished up with the same problem as Steve with my efficiency. My previous (An Irish Red) got a couple of points above my 83-84% average at 87% but the stout finished up at 74%. Still trying to work out where I went wrong? Still got 4.98% ABV so it's not too bad.
I lowered all my mash water to Ph6.2. Maybe this is too low what with all the dark grains i used?

TP :beer:

PS --- The Ph of our local water (If my old 2nd hand Ph meter is correct?) was Ph8.4 last Friday.

 

[Stuster]

TP, it's not so much the pH of the mash water you need to worry about but the pH of the mash itself. Sydney water is around the 8 mark but it's very soft and with anything but a very light malt it will drop down to 5.2 or so in the mash. It makes sense that adding acid to your water to reduce the pH along with the dark grains will leave you with a mash pH that's too low (depending on the composition of your water).

SJW, I'm not sure about Newcastle water either, but the 5.2 stabiliser is apparently most suitable for hard water and it might be doing your pH too low in the mash if you have soft water.

 

[clay]

Am I correct in assuming you get lower efficiency with higher OG beers? I usually hit 80% for 1050 beers but hit 88% for an English Mild I did recently (OG 1034)

 

[BenH]

Am I correct in assuming you get lower efficiency with higher OG beers?

That makes sense to me. With a higher OG, your final runnings will be more concentrated - therefore the liquid retained by the grains will be a higher concentration, so more sugars are left behind in the mash tun.

 

[TidalPete]

TP, it's not so much the pH of the mash water you need to worry about but the pH of the mash itself. Sydney water is around the 8 mark but it's very soft and with anything but a very light malt it will drop down to 5.2 or so in the mash. It makes sense that adding acid to your water to reduce the pH along with the dark grains will leave you with a mash pH that's too low (depending on the composition of your water).

SJW, I'm not sure about Newcastle water either, but the 5.2 stabiliser is apparently most suitable for hard water and it might be doing your pH too low in the mash if you have soft water.

And there seems to be my answer to this Oatmeal Stout problem.
Just checked my Promash & got 84% effiency for my Chocolate Spiced Porter without any fiddling around with the Ph. ---- My bad.
Many thanks Stuster. :icon_cheers:

TP :beer:

 

[Frank]

SJW
Any chance the grain was weighted incorrectly?
Did your LHBS supply the grist ready to go? or Do you weigh your own grain bill out to ensure the accuracy?

Boston

 

[SJW]

Can't blame anyone else for that, as I buy all my base malt in bulk, so I do all my own measurments. I am not too worried as its turning out very nice.