Consistent mash efficiency

[James Sturman]

Hello,

I was hoping someone might be able to provide some advice/knowledge so that I can better understand the mashing process and obtain more consistent mash efficiency making it easier for me to prepare and stick to my recipes.   

Some background info for consideration...

I recently had a 50lt keg converted into a HLT with an electric element installed and temperature control. Over this past weekend I brewed my second batch using this new equipment and the mash efficiency was significantly lower than that of the first batch I brewed before Christmas. The mash efficiency of my 1st batch was around 80% and this second batch was around 65-66% so quite a big discrepancy.

The differences between batch 1 and 2 are:

The recipe. Batch 1 used golden promise as the base malt and a good hit of dark malt. The base malt for batch 2 was Malteurop Pale Malt. Is golden promise easier to mash or did the addition of dark malt help? FYI the volume of malt was almost the same for both batches, but more hops were added to the boil of batch 2.

Sparging. I performed what I believe is called fly sparging for both batches with the sparge liquor set to 78°C, but the rate of runoff was slightly faster for Batch 2 at approx 750ml per min (around 500ml per min for batch 1). Perhaps this was too fast?

Mash temp. The mash temp for Batch 1 was around 66°C and for Batch 2 it was 68-70°C. In addition, it took me a while to get my mash temp for batch 2 correct. I spent extra time stirring it and messing around trying to hit my desired mash temp and get even temperatures throughout the grainbed. 

Everything else was more or less the same. I just use tap water and don't mess around with it. I aim to mash for 60-75mins and to sparge for around 1.5hrs.

I have read that the pH of the mash is important and that a pH value of 5 or 5.2 is desirable. Apparently dark malts can help with this as well as the addition of salts and minerals to the water. Does anyone measure the pH of their mash or brew in Wellington and add brewing salts to the water?

If I could consistently hit a mash efficiency of 70-75% I'd be a happy man. 80% would be awesome.

Thanks,

James  

[Karl Hayes]

Hi James.

I'm no expert but here's my 2 cents in any case.

First of all, which efficiency are you talking about? Into the kettle or into the fermenter? I'll presume into the kettle and these numbers are still acceptable for someone at the beginning of all-grain home-brewing.

Golden Promise has about 5% less sugar yield per weight than Malteurop Pale Malt so your first batch should be less efficient on this basis alone.

Sparging speed will cause a difference but 750ml per minute is still within normal limits

Temperature difference might be the biggie - you may have killed some enzymes and gotten poor conversion, especially with the uneven temperatures you experienced.

My advice would be to first concentrate on getting your strike water right for a consistent mash temp. You can worry about PH levels some way down the track. (There are numerous threads on this forum about PH levels, and one in particular with a copy of the water report from the city council I think)

Having said all that, we amateurs are in the enviable position among brewers of being able to spend a couple of extra dollars in order to get a less efficient but tastier beer. My approach has been to use taste as a judge of a good beer and let the efficiency take care of itself.

Best of luck..

[Karl Hayes]

Found this link which has a go at explaining the link between mashing temperature and efficiency. Have a look at the table a third of the way down the page.

[Murray]

Hi Karl,

Nice link, I think it refers more to apparent limit of attenuation (fermentability of the extract), rather than efficiency or total sugar extracted.  I don't believe OG would be greatly affected by temp (but personally haven't pushed a mash outside of a 64-69c range to find out! Raising the temp at the end of the sparge does help, as does a slower sparge. 

James, were the two grains crushed the same? That have have a huge impact in my experience. Even running two basemalts through the same mill gap can give a different crush due to grain size and so significantly effect eff%.

80% is pretty darn good for homebrewing (much more your start getting some nasty tannic character from the husks in my experience).

On water, WCC (capacity infrastructure services) can give you current numbers on water in your suburb.

One final thought, when I first started all-grain brewing I calculated my first batch at 82% efficiency only I hadn't accounted for the fact I only had 19.5 litres of wort (instead of the recipes 23), so in fact I only had 70% efficiency, easy mistake-a to make-a.

Hope that helps

[James Sturman]

Hi Karl and Murray,

Thanks for the advice. I think Karl may be right about the temperature difference in batch 2. It's likely that my mash temp was too high for too long and I killed/deactivated some enzymes. Next time I'll have more confidence in my strike temp and let the temp of the grainbed settle down before I start messing with it.

I had both of the grains milled at the homebrew store so I assume the crush was similar for both batches. This is something I have no control over as I don't own my own mill... yet.

Regarding water I'll get in contact with WCC and ask for a water report. I was playing with John Palmer's Residual Alkalinity Spreadsheet last night and it would be interesting to see what happens when I enter the stats for Wellington water. A brewer friend in Germany recommended the use of acid malt to bring the pH down if required. Apparently, having the correct mash pH can help increase efficiency. 

Thanks again

[Liam Callaghan]

I still have issues with mine mate and I have been using it for 10 years haha.  Your certainly not on your own.

Some good tips above, doesn't always help on the day :p

Look away and your strike water is stting at 88 instead of 78... DOH!

[Dan]

Hey James

I brew with Wellington water (Te Marua supply), the figures for it are on this forum somewhere, just do a search. It is quite soft water so adding  a little gypsum to bring it up to 50ppm can help.

I batch sparge in a false bottom chilly. I certainly have not mastered yet (have done about 10 brews) and  swing between 65% and 55% sometimes!!  For me my sparging volumes and times are the key thing and I get the crap eff when I rush the sparge.