Understanding 'efficiency'

[Spikesdad]

hi all,

When I see that the brew has an efficiency of '75% or 80%' etc, what exactly is it were looking for, and how do I calculate it?

Thx in advance, Dave

[OldSpeckledBadger]

Basically it's the %age of the malt which ends up in the FV as fermentable sugars. Many recipes use a value of 75% to predict the OG of the wort. If your efficiency is better than that you'll get slightly stronger beer. If it's worse you'll get slightly weaker beer. Program such as BeerEngine can calculate your efficiency for you.

[boingy]

I'm going to try to put it into different words!

Each grain type has an "extract potential" which is the maximum theoretical fermentable stuff that can be extracted from the grain during the mash. In practice, of course, we can't extract it all so the efficiency is a measure of how much we did manage to extract. A lower efficiency means that you need more grain to get the same OG. As Badger says, the easiest way to calculate it is to use some brewing software. You don't really need to calculate it at all unless you are trying to be very precise. If you consistently find your OG is lower than a recipe states then you just need to boost the grain quantities a bit next time you brew and vice versa. High efficiency is one of those things brewers like to boast about but as long as your efficiency is fairly consistent from brew to brew then it is easy to adjust for it.

[adm]

Just to add to Mr. Badger's answer, the way I think about it is that each different type of malt will have a certain amounts of "sugar points" that you can get from it per kilo.

There's a standard way to work out what that number is - and the maltsters provide malt specification sheets that give you this information (on the other hand, you can use rule of thumb numbers for this within reason - i.e. 300 points per kilo of Pale Malt)

For example, Fawcetts have a list here: http://www.fawcett-maltsters.co.uk/specif.htm

To take one specific one - they show their Maris Otter Pale Malt has a maximum extractable yield of 305 "points" per kilo of grain, when mashed. They use a test called a "Congress Mash" (I think) to establish these results - but it's not really important. What is, is that number - 305 points per kilo of grain. If you mashed one kilo of that grain and got that result, you'd have 100% efficiency.

So. How does that help us.....?

Well, let's say that we mash five kilos of Fawcetts Maris Otter, and get a result of 20 litres of pre-boil wort at 1.050......then what we have is actually 50 "sugar points" (just ditch the 1 at the front of the hydrometer reading) in each of 20 litres - so a total of 20*50=1000 "points" yielded from 5 kilos of grain.

But each of those kilos of grain actually had a potential of 305 "points"....5kg*305= 1525 potential points.

Now, we got 1000 out of the total available 1525 points - so our efficiency is (1000/1525)*100 = 65.57%

That's our efficiency for that mash - we got about 2/3rd of the potentially available sugar out of the grain.

If instead, we got 24L of wort at 1054, that would be 24*54=1296 points. In this case, our efficiency would be (1296/1525)*100 = 84.98% efficiency.

Simples!

[garwatts]

Couldn't have put it better myself

[Spikesdad]

Hi guys, thanks for those great replies, which leaves me with another Q...

How do I improve on efficiency, and how do I really know if I'm hitting 70% or 75% or whatever?

[OldSpeckledBadger]

How do I improve on efficiency,/quote]

How do you know you need to?

and how do I really know if I'm hitting 70% or 75% or whatever?

Put your recipe into BeerEngine, brew the beer, feed the volume collected in the FV plus its specific gravity (temperature corrected to 20C) and BeerEngine will tell you what your efficiency is.

[adm]

How do I improve on efficiency

I'm no expert, but I'd say:

Water treatment - getting your mash pH correct
Stable Mash Temperature Control
(Both of the above are about getting the relevant enzymes that convert starch to sugar working in the best possible way - you have to create the correct environment for them)
If you are batch sparging, stirring the mash well before sparging to rinse as much sugar into suspension as possible. If you are fly sparging, maybe using a well designed false bottom or manifold to make sure you are rinsing the grain well.

[CrownCap]

Don't worry about your efficiency. Commercial brewers do as it affects profitability. As a home brewer the differences are small - quality is likely more important, and high efficiency can be the enemy of quality.

Consistency and therefore predictability should be your goal.

[Spikesdad]

Hi thanks again for replies, i guess theres not too much sleep to lose over it, but here goes...

Water treatment - getting your mash pH correct

My pH was quite high... 5.6-5.7 ish... how can i lower this? I am in a soft water area.

Stable Mash Temperature Control

That wasn't too bad... lost just under 1 deg C., over 75 mins.

If you are batch sparging, stirring the mash well before sparging to rinse as much sugar into suspension as possible

Yes, i'm batch sparging untill i get a bit more confidence and eguipment to fly sparge. I used Daabs calc. http://www.jimsbeerkit.co.uk/batch_calculator.html to do the volumes.
Ok one more Q... when it says...

Total Quantity of Water Required For Batch #1: L


Mash Volume: L


Top Up With: L

the question is... at the- Top Up With: L -do i add that volume to the tun before first run off, or, run off, add that fist voume, run off again, then add second batch volume?

Thank again guys, sorry for being a pest

[adm]

OK - on the water treatment, if you get the Total Alkalinity correct, then you are 90% of the way there. To do this, you need to know the current Total Alkalinity (TA) of your water. If you are lucky, your water supplier will publish this number - so give them a call and check their website.

If not, then you'll need to test for it. You can buy a test kit (made by Salifert) from your local acquarium shop if you have one - for about £7, which will last you for almost ever....

Have a read up on here on some of the old but long running water treatment threads. Chris also did some videos of how to test your water with the salifert kit.

Once you have your TA number verified, you can then easily adjust your brewing water so that your mash pH will always settle somewhere around 5.2pH. It's easy to do using an acid called CRS. Again - there's lots of discussions here if you search.

For the batch sparging, you mash in with the first amount, then after the mash is complete, add the "top up" volume directly to the mash before you run anything off. Give it all a REALLY GOOD stir around, then let it settle, then run it off into the kettle. Once that's done, then refill the mash tun with the second batch amount, give it another really good stir and run off like the last lot.

[Spikesdad]

Great Stuff!!

Thanks guys.. I did a sort of "practise brew" friday, (being an eager beaver, an all), and all i think i might have got wrong is second batch temp too high, and sparging way too fast. But we live and learn.

I wont be too concerned about water treatment and efficiency jusy yet, will concentrate on the basics of the mash and sparge first, but, will monitor pH with future brews and take it from there.

Thanks again, dave

[benna]

Thanks a lot for all that adm, I had been wondering the same questions about working out efficieny, I'm yet to do my first ag brew but it is fast approaching and it's good to have an idea of efficiency even if it's not the be all and end all.

Just one thing to clarify then, if I can't get individual specification sheets for the malt I use can I just use Fawcetts as a standard?

Cheers,
Ben

[adm]

Just one thing to clarify then, if I can't get individual specification sheets for the malt I use can I just use Fawcetts as a standard?

Yep! Or just use a rule of thumb of 300 for pale malts and 275 for Crystals and Coloured malts and you'll be close enough for Government work!

[benna]

Brilliant! Thanks for that!