High ABV

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Laurentic
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High ABV

Post by Laurentic » Wed Apr 24, 2019 7:56 pm

Hi, I have a couple of queries so I will put them into two threads so one doesn't detract from t'other!

First up is ABV. I brew all grain using recipes from Graham Wheeler's "Brew your own British Real Ale" book, typically recently has been Exe Valley Autumn Glory, Courage Directors and Timothy Taylor Landlord.

In all cases I follow the recipe for a 25 litre brew. I use a Bulldog Brewer Mk1 system, using 20l water for the mash (which you have to do otherwise with the system there is insufficient water) recirculated, then about 10l water for the sparge.

However, in all cases I end up with a higher OG at the start and so it results in a higher ABV at the finish, say instead of 1046 OG I will get say 1056. My FG will end up at about 1010, won't go down any further, so a ABV of 5.9% instead of 5%.

Any ideas why anyone?

Chris

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alexlark
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Re: High ABV

Post by alexlark » Wed Apr 24, 2019 8:24 pm

First thing I'd say is your efficiency is probably higher than that of the recipe. Happens to me all the time, especially with recipies using less malt. It seems to increase my efficiency further as I brew BIAB.

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Re: High ABV

Post by guypettigrew » Wed Apr 24, 2019 8:47 pm

Laurentic wrote:
Wed Apr 24, 2019 7:56 pm

However, in all cases I end up with a higher OG at the start and so it results in a higher ABV at the finish, say instead of 1046 OG I will get say 1056.

Any ideas why anyone?

Chris
If you're getting 10 points of OG higher then expected, this is a 20% increase in efficiency. A huge amount!

Can you tell us a bit more, please, with an example?

Guy

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chastuck
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Re: High ABV

Post by chastuck » Wed Apr 24, 2019 9:39 pm

Having spoken to Graham Wheeler long ago about extract rates, may he rest in peace, he did say that he rather assumed that brewers would get a poor efficiency in their processes and couldn't possibly rival commercial brewers extract rates. We also have to remember that his books are quite old now and malts available to home brewers at the time were not as good as we get now. Hence, you should not be surprised that using his recipes with modern malts and using modern home brew equipment gives you a higher efficiency.

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Kev888
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Re: High ABV

Post by Kev888 » Thu Apr 25, 2019 9:31 am

Yes, as above: different grains will offer different amounts of malty sugariness, and (in particular) different brewing systems and methods will extract and then lose different percentages of this. To hit the intended numbers therefore, recipes will always need adjusting to suit the brewer's own circumstances, at least unless they happened to be formulated on the same brewing system and using the same techniques.

With experience and measurement, you will be able to identify how your setup and technique performs, and so then predict what adjustments are needed to arrive more or less at the intended Original Gravity. It helps to have records to build this picture, so in addition to fermenter gravities, record other things including the grain amounts and its potential gravity, the pre-boil wort gravity and volume, the post boil wort gravity and volume and the volume making it to the fermenter.

Another common reason for unexpected gravity is that the volume isn't as expected - e.g. through using different amounts of liquor, or having a different evaporation rate during the boil. If there is less liquor used or if there was more evaporation then this will concentrate the sugars, making the gravity higher, so you can't really judge extraction efficiency without knowing both the gravity and the volume.

As you may gather, another common cause of differences is in the measurement. Errors with weights and volumes, not just gravity, can give a misleading picture. Don't trust manufacturer's volume markings until you've verified their accuracy, and make sure the wort is at or around your hydrometer's calibrated temperature when taking gravity readings, and test that it reads 1.000 in water (as some are not very accurate).
Last edited by Kev888 on Thu Apr 25, 2019 10:07 am, edited 1 time in total.
Kev

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Cobnut
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Re: High ABV

Post by Cobnut » Thu Apr 25, 2019 9:37 am

I had a similar issue when brewing GW's Fuller's ESB clone using my Grainfather (one of my early brews with the GF). Target ABV was c. 5%, but I ended up at around 6%. I agree with others that the assumed efficiency in these recipes is quite a bit lower than can be achieved and I now adjust my efficiency assumption for "normal strength" beers. Higher ABV beers (not that I grew many) do not achieve such high efficiencies typically.
And occasionally, I get a brew which doesn't hit my expectations, but it's usually perfectly drinkable!
Cheers!
(b)
Fermenting: Keyworth Mid-season single hop pale ale
Conditioning: SMASH Keeping Ale (Chevallier, First Gold, Voss Kveik)
Drinking: Munich Helles, Haflinger (rather odd weizenbock), Mocha Stout, 'Ol 'Enry Brut IPA, Cherry Chocolate Dubbel Trubbel, A Galaxy Far, Far Away Black IPA (or maybe it's an American Stout?)
Planning: Looking for suggestions...

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Re: High ABV

Post by Kingfisher4 » Thu Apr 25, 2019 4:06 pm

My recollection is that GW did state somewhere in that book what the assumed malt sugar extraction efficiency would be for the recipes, off the top of my head I think it was about 70%, hence your higher starting gravity with his recipes.

I have found exactly the same, with my Grainfather achieving approximately 85% “efficiency”.

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charliemartin
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Re: High ABV

Post by charliemartin » Fri Apr 26, 2019 7:53 am

You are only using 30 litres total water, of which approximately 1 litre per kilo of grain will be absorbed by the grist.
That leaves 25-26 litres pre-boil, but you are aiming for 25 litres post-boil if you are following Graham Wheeler's 25 litre recipes.
The boil will evaporate some of the wort leaving you with less than 25 litres, hence a more concentrated wort.
For my system I usually aim for about 32 litres into the kettle which boils down to 23 litres after losses to evaporation and hop absorption etc.
How much wort do you have going into your FV after the boil?

Cheers,
Charliemartin

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Laurentic
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Re: High ABV

Post by Laurentic » Sat Apr 27, 2019 12:19 pm

Hi - as per my other current post, sorry for the lack of reply but I have been somewhat sidetracked this week.

Reflecting on the comments made, it was interesting to hear that we can expect to achieve higher extraction efficiencies using todays available malts and brewing equipment. Being a relative newcomer to the hobby I am not sure how to compensate for higher efficiencies, but I am guessing it must be in either the amount of grain used or the time taken for the mash.

As everything I read quotes a mash time of 90 minutes I am reluctant to go down that route, but how does one arrive at adjusting what amount of grain to use? Is it by trial and error or by calculation? If by calculation this would be reasonably simple I assume if using just one grain malt, but recipes using say crystal malt, black malt and/or torrefied malt as well would have to have all those item quantities also modified? And what about the hop quantities, do they get modified too?

I am using mostly Maris Otter Pale Malt, but sometimes Golden Promise, hops as per each recipe.

Charliemartin - sorry to have slightly mislead you on volumes, the OP should have read that I use about a minimum of 10 litres of sparge water. Sometimes I use a bit more. If I am doing a 25 litre brew then at start of boil then I ensure I have 30 litres in the Bulldog Brewer, if doing a 23 brew then about 28 litres at start of boil. I find this gives me about the 25 or 23 litres I am looking for in the FV with a minimum left in the Brewer. Evaporation rates seem to vary according to what power I set the Brewer to obviously, but also it seems as to how I add the hops; I used to add hops in a weighted muslin bag, then I tried a hop spider - once, the binned the idea, temperature inside the spider was up to 9 deg.C below boiling! - and am now just adding the hops loose straight into the vessel. If evaporation rates look like resulting in too little water I boil up a litre of two and add a bit to the boil during the boil period, or if the volume in the FV doesn't make the mark I add sufficient cool water to the FV to bring it back up the required volume. I can't start with more than 30 litres in the Brewer at start of boil as that is the max it will hold!

Guy - you asked for an example; one of the worst examples was an OG of 1056 and a FG of 1010, giving an ABV of about 5.9%, against the recipe figures of OG 1046 and FG 1008 giving an ABV of 5%. This was for Courage Directors bitter recipe from Graham Wheelers British Real Ale book, following the recipe ingredients and method exactly as suggested in the book but using water volumes to suit the Brewer.

Chris

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Re: High ABV

Post by guypettigrew » Sat Apr 27, 2019 1:34 pm

One of the ways to work out your grain amounts is to use Graham Wheeler's Beer Engine. Available from the JBK links above. Or just go to this link.

It allows you to enter your efficiency, then it works all the rest of the stuff out for you as you enter your intended grain and hop details. Or you can enter details from a brew and it'll calculate your efficiency.

Like most new things, it's a bit confusing to start with, but well worth getting to know it. I find it invaluable.

Guy

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Kev888
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Re: High ABV

Post by Kev888 » Sat Apr 27, 2019 2:29 pm

Use grain quantity (not mash time) to adjust for efficiency. The maltster will usually offer figures for the potential extract of their grains - which is the extract that it will give in a standard lab test. This differs between grains, but if you can't find it for your particular grain then there are rough figures for what is normal for the grain type around the net, or a lot of software already has this info built in. (This is not efficiency, it is about the actual grain).

If in your mash/sparge you got the same extract as the lab's potential extract, then your efficiency would be considered 100%. Normally though you will get a lower amount, say 80% of the potential for example.

The convention is to quote potential extract as gravity achieved in the volume it is diluted by per weight of grain used (e.g. litre degrees per kg in metric). So if a pale malt were to offer an official potential extract of 300 gravity points per kg of grain in 1 litre, then that is equivalent to 30 points (1.030) in 10 litres or 3 points (1.003) in 100Litres. If you had a mash efficiency of 66.6% (which would be unusually low, but for the sake of easy example) you would actually achieve 66.6% of the official potential - i.e. 1.020 in 10 litres or 1.002 in 100 litres per kg of grain.

You won't know your own efficiency in advance, it will be discovered as you brew. But once known it can then be used to predict how much of a given grain you need to achieve the desired gravities in future brews.
Kev

Laurentic
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Re: High ABV

Post by Laurentic » Sun Apr 28, 2019 11:10 am

Now reading "How to Brew" by John Palmer which goes into some detail the theory and calculations I need to know about most aspects of brewing it would appear at first glance.

Chris

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