Missing pre boil gravity from mash

I am 2 mashes into a bag of Canadian 2 row, where I have missed my expected preboil gravity target by about 10 points each time.  My expected pre boil volumes have been fairly consistent. 

I am relatively new to mashing, but my previous 4 or 5 mashes have been fairly good for meeting targets.  I just emailed the malting company for a spec sheet on this grain since I believe it is causing my issues.  I did an iodine test at the end of the mash and it showed no starch.

In order to get back to hitting my targets, what is my best bet? Should I:

1) change the average yield of this grain using beer Smith? (Adjust grain yield until the recipes show my value for preboil gravity, then average the result)

2) change my brew house efficiency until it matches my numbers

Or is there something I am missing totally? Beer Smith has been a lot nicer to use since moving away from extract, but it still causes some issues.. or perhaps it's just me. Haha

Any insight is appreciated!

What maltsters can do is both amazing and little understood by brewers. We brewers simplify it down to sprouting and kilning, without realizing that the malt undergoes a lot more scrutiny and quality control than we realize. Then, we blame the malt when a lot of other brewer process related issues could be the real issue.

Is this malt the same as what you were buying from your source, prior to buying bulk? If so, then this is likely an issue with milling. If it's premilled, and in a humid environment, the malt could be losing potency. I'm glad you asked for the lot analysis and would like to see it, too.

Do you check pH of your mash? If so, are you using a calibrated meter? Proper pH is probably at the top of the list for things that increase extract from the grain.

What's your liquor to grist ratio? Too much mash water can interfere with pH and reduce enzyme effectiveness.

How are you mashing and sparging? If you're doing a lot of recirculation (like HERMS ir RIMS systems), or are sparging very quickly, you could be compacting the grain bed, and the water could be channeling through the grain bed instead of percolating through it.

Thanks for the reply!  I have been doing a lot of further reading and have realized that I need to learn a few more things about the mash in general. 

The grain itself comes from a totally different supplier.  My last sack of 2row was gambrinus, and what I have now comes from 'prairie malting limited.'  I mill my own grain, and have yet to change the gap.  Perhaps that's also a contributing factor.

Ph is probably an issue, as I currently do not have a means of checking it.  This will change in the near future! 

My mash run is a 55qt rectangular cooler, and use a full size voile bag inside the cooler in lieu of a manifold.  I have been using a ratio of about 2.6L/KG of grain, mashing in at 75c in order to get a mash temp of about 69C(for added body).  I batch sparge twice and stir the bed before collecting the second and third runnings.  The gravity of the last running is typically down to about 1.01.  I check all runnings with a refractometer.

Although I am certainly not yet controlling all the variables, I have been quite constant in my methods. This is why I am looking at the malt as being the suspect in this case..

I have had to add about a kilogram of dme to make my targets after my last two mashes with this new grain.  I keep it around for such occasions, but would definitely prefer to sort out these mashing issues!

I have just recently been learning a bit about the water chemistry side of things too, so hopefully I'll be able to take control of a few more of these variables. 

Thanks for the help!

Gambrinus is an independent maltster, which just about all suppliers carry. Their malt plant is near Vernon, BC. Gambrinus owns Spoetzl Brewing in Texas, as well. You probably know that brewery better as the makers of Shiner Beers.

Prairie Malting is owned by Cargill since 2011 and is a listed but unspecified brand in their catalog. Their malting plant is in Biggar, Saskatchewan, which makes both base and specialty malts that are marketed under the Cargill brand.

That points to high quality malt standards. Cargill base malts have a minimum extract spec of 80% FGDB. They target low total protein (5% soluble, 11.5% total) and high diastatic potential (110 deg. lintner). Keep in mind that these are minimum specs to pass QA and individual lots typically exceed these values.

All of that to say that you've not bought inferior malt from what you're used to. However, that doesn't mean that it will act the same way in the mill or mash.

Buying a pH meter (with a resolution of +/- 0.02) will make a big difference in troubleshooting. Water chemistry can get confusing, but the main goal is to get the proper mash pH worked out. Then, using minerals to drive flavor goals (and adjust pH) becomes a lot easier.

Another metric is to take a first wort gravity reading. With your liquor to grist ratio, first wort gravity should be at least 1.090 with full conversion and extraction.

I agree,  if the Malting companies didn't live up to certain standards they probably wouldn't be in business very long.

I have come across that first wort potential before, and definitely did not make it on these last batches.  I will have to look into previous ones.  I believe I saw a table for first wort gravity on this forum.  Would that gravity be fairly consistent across beer styles, or would it differ for styles with more dark/roasted malt.

Finally, if I check the gravity of the mash on brew day and it is lower then that, what can I do to increase it? Would that be a function of it just mashing longer as long as the pH and temperature is proper?

GreatWhiteNorthBrewer said:

I believe I saw a table for first wort gravity on this forum.  Would that gravity be fairly consistent across beer styles, or would it differ for styles with more dark/roasted malt.

Finally, if I check the gravity of the mash on brew day and it is lower then that, what can I do to increase it? Would that be a function of it just mashing longer as long as the pH and temperature is proper?

Click to expand...

The table you're referring to is from http://www.braukaiser.com/wiki/index.php?title=Understanding_Efficiency and it's based on 100% pale malt. The number I gave you for your grist ratio is for a thinner mash that the chart predicts because I find it reflects brewery attainable results with specialty malts.

If the gravity is lower than predicted, you need to first address the crush. I've had issues with certain pale malts being too thin to properly mill, for me. A screen analysis of the crush is the most accurate way to calibrate the mill gap, but the old "credit card gap" is pretty reliable.

In real time, if the grain just isn't yielding the right first wort gravity, often a few extra minutes usually helps it finish. The longest I've ever had to wait is 30 minutes.