Mash Efficiency

[vaudy]

After my visit as a guest to the site, I have now registered having completed my first brew this year, it is over a year since I last brewed.

I brewed a bitter, 10 gallons, carrying out the mash in two five gallone brew bins insultated, the temp dropped approx 4 deg C over the mash period.
The sparge went well, and I retrieved approx 10 gallons which was boiled for 1 1/2 hours. During the boil I added water to compensate for evaportation with a final top up along with hops and Irish Moss duirng the last 15 minutes.
The wort was then cooled and drained through the hops (in this particular brew, a large volume of hops). I retrieved 10 gallons without having to add any water.

Having worked out the efficiency of the extraction I was shocked when it was only 74%, do you think this could be due to the amount of extract retained by the hops, should I omit adding some of the water for evaporation and sparge the hops instead.
The brew came out at the desired o.g. having been generous with the malt in the beginning.

I look forward to any advice.

Cheers
Vaudy

[sagwalla]

I calculated my average efficiency based on 6 batches with the same grain bill and came up with 73%. I used that number to plan my last batch and I nailed the OG within one point, so I trust that it's about what I can get. I'm quite happy with that.

[Andy]

I understand what the mash efficiency is and how to calculate it however I'm not sure at what stage in the proceedings the post-mash gravity is taken. Is it post-sparge taken from the full volume of wort which is to be boiled ?

[Jim]

Andy, I calculate my efficiency for the whole process. So the ingredients will have a certain extract potential, and the final beer has a certain gravity. The difference between the two depends on the combined efficiency of mashing, sparging, run off after boiling plus anything else.

Pure mash efficiency is impossible to measure, because you can't measure it until after you've sparged the grains, but you could calculate your mash + sparge efficiency by measuring the specific gravity after sparging.

You always need to take the volume of wort when you calculate efficiency, whichever stage it's at.

I reckon I average around 80%.

[Andy]

Cheers Jim,

So you get approx 80% "end-to-end" as it were ?