Thanks browndog
Does that mean I can I write a bit more now? LOL. (Crundle have a read of the below and then I am going to PM you.)
Why 2% Improvements in Efficiency are Impractical to Measure
There is nothing wrong with trying to improve efficiency, nothing wrong at all but there is a reason why very experienced and successful brewers like browndog are a little dismissive of it. In fact, you'll find only two groups of brewers obsessed by efficiency - new brewers and experienced brewers who love the science of brewing.
This is all good and enjoyable but we need to look at it realistically. Let's have a look at just how hard it is to see if your efficiency increases by 2% or more using a finer crush.
[This will be a ridiculously long post and no need to read it all. The number of points in this post alone should show how difficult it is to measure small efficiency increases and this is the sole aim of this post.]
Let's have a look at some of the minimal equipment you will need to test if a finer crush gives better efficiency than a coarser crush and by how much.
1. 15kg accurate scales. - You'll want to weigh your own grain for the brews you do. Scales will come in handy for measuring your spent grain as well - lol
2. Filter Paper - To get accurate hydrometer readings you will need to filter all your wort samples. (Thanks Nev, I didn't know that one until you told me.)
3. Accurate Hydrometer - These are rare and make sure you use the same one on each brew.
4. Calibrated Scientific Jug - Use this to calibrate
all your other volume equipment.
Next you need to determine at what stage of the brew you are going to measure your efficiency. To measure the true difference between the two crushes,
you will have to measure how much clear beer you get from your fermenter.
Your
efficiency into the kettle will not answer the question. There are three questions to answer here and the third is very important but can't be answered at the into the kettle stage. The three questions are...
1. Did I get more or less wort into the kettle?
2. Was it of higher or lower gravity?
3. How much trub did I get in my kettle?
The only scientific way of measuring efficiency is clear beer from the fermenter. Just the same as comparing a counter-flowed beer or no-chilled beer to an immersion chilled beer. The former will have a higher efficiency into the fermenter (due to a tad more trub) but probably the exactly same efficiency from the fermenter.
A testing of finer versus coarser crush would be even more important to test at the 'from the fermenter,' stage as you really would want to know just how much of that extra volume into the kettle is solids etc.
Now we have all the above sorted, we need to get to the actual measuring side of things - lol!
For example, any experienced traditional brewer knows that you can leave the wort draining from your mash tun for a long long time and this can add at least 1.5 litres to your kettle - more if my memory serves me correctly. There's about a 5% increase in efficiency straight away! So for traditional brewers, you'd have to set a time when you turn the mash tun tap off. For BIABers, it will be harder to get consistent results. How hard are you going to squeeze and/or how long are you prepared to hang and drain your bag? You will have to do it the same way for every brew.
Next you will need to measure your OG and the latest stage you can do this is into the fermenter. But you can't measure the true volume at this stage as you don't know how much extra or less a finer crush will add trub to your fermenter.
To get your volume, you will have to wait until the brew is fermenterd out, drain the same clarity of wort from it and then measure the trub!!!
I haven't even talked about the inaccuracies of measurement but an article* I read a while back acknowledges a plus or - 5% measurement error just on the measurement side of things alone! So, I wasn't exaggerating in my last post when I said that you would need to do 20 brews to detect a 2% increase in efficiency. Do 10 identical recipes with the coarse crush and then 10 with the fine crush!
[*Couldn't find that article quickly but
here is one that looks interesting.]
I could write more on the problems of measurement but surely the above is enough?
Efficiency is fun to explore and talk about but we do need to be realistic and convey efficiency figures usefully which is quite difficult.
A better goal for new brewers is the consistency that browndog mentioned. A new brewer is far better off in the long run establishing convenient cut-off points of measurement. For example, a new traditional brewer should say turn their mash tun tap off at the start of the boil, whilst a new BIAB brewer might like to squeeze or hang until the boil start.
New brewers focussed on measurement would also be far better off getting some accurate measuring jugs and seeing how much trub settles out at varying stages of the brewing process. This can be a bit of fun and certainly educational.
The
ONLY benefit I can see for a new brewer having a basic understanding of efficiency is to know if something is majorly wrong. And guys like Crundle will be hard pressed finding good quality information on even the term 'efficiency.' He is probably measuring his efficiency on the more honest end of the scale. Even 55% from the fermenter is perfectly acceptable.
The more you brew and learn, the more you realise that any efficiency figure you see quoted will probably be a lot more useful to the person quoting it than you. Efficiency is very individual to the brewer and their equipment. It is a very mis-used term.
The most useful figure to convey to other brewers who wish to replicate your brew is simply the OG you measured and even then you better cross your fingers that their hydrometer reads anywhere near yours - lol!
Thanks heaps browndog. I'm even more relaxed now!!!
:beer:
Pat
