Hitting my OG

[jambop]

For a strike volume of 20 L and mash bill of 4.45 kg, I get your max mash SG @ 100% conversion as 1.0593. Your measured 1.055 at end of mash-out works out to 92% conversion efficiency. (This is using a rigorous method for calculating efficiency rather than the simple 55 / 59.3 = 92.75%.) I get your mash efficiency at 87.6%. I get a higher mash efficiency than your 84% because I correct for the moisture content of the grain (assumed to be 4%) which effectively decreases your grain bill weight.

So, even with a 100 minute mash (including mash out) you still are not achieving 100% conversion efficiency with your crush. But an 87% mash efficiency is nothing to sneeze at.

Brew on

I use Grainfather's ready made calculator Their calculator is suppose to be universal for all their products so I just go with their figures.

 

[DBhomebrew]

Is a fine[r] crush required for full conversion? Maybe

Is a fine crush detrimental (in regards to a bag in a kettle)? No.

 

[doug293cz]

I use Grainfather's ready made calculator Their calculator is suppose to be universal for all their products so I just go with their figures.

Even if the calculator you use isn't totally rigorous in accounting for all variables (eg moisture content), it is still useful for recipe generation, results predictions and comparison with actual results. Any absolute accuracy errors are self canceling when used this way.

The biggest problem with most SG prediction software (a part of most recipe generation software) is the failure to account for lauter efficiency changing with changes in the grain bill weight to pre-boil volume ratio (lauter efficiency decreases as ratio increases.) The change in lauter efficiency with grain/volume ratio also affects mash efficiency and brewhouse efficiency. So, if the user doesn't account for the lauter efficiency change in the brewhouse or mash efficiency they input into the software the SG predictions won't be very accurate.

The shortcoming in the previous paragraph is what leads to posts that can be paraphrased as: "I tried to brew a big beer, but my efficiency sucked, and my OG came out low. What happened?"

Brew on

 

[jambop]

One other issue I have with overly fine grinding malt grains is the possibility of extracting unwanted tannins etc from the much more finely ground husks which can very easily happen if water chemistry is out of spec .

 

[Hoochin'Fool]

@doug293cz Is there a chart (or formula) out there somewhere that maps out efficiency drop-offs based on how thick the mash is? No rinsing/lautering, just if you soak 1 lb malt in a 2 quarts of water (very thin) at 152F for 60 minutes, you should get be able to get 99% of the theoretically extractable sugars in the malt. And if you soak 1 lb malt in 1 quart of water (very thick) at same temp/time, you can expect to only get 65% of the theoretically extractable sugars...

Something along the lines of:
description | mash thickness | max efficiency
------------+----------------+---------------
very thin | 2.0 | 99%
thin | 1.6 | 95%
average | 1.33 | 90%
thick | 1.2 | 80%
very thick | 1.0 | 65%

If not, it seems like a simple enough experiment to try cheaply at home (small pot and small amount of malt, put it in an oven to keep temp consistent).
Obviously independent variables for different brewers: mill gap, water chemistry, malt choice*, malt freshness...

Bah, forum software doesn't actually do fixed-width font formatting

*Actually, if you're using brewing software for the recipe, it should know the max pts of sugar for each malt, so that's probably not a factor, tho freshness of the malt surely would be...

 

[doug293cz]

@doug293cz Is there a chart (or formula) out there somewhere that maps out efficiency drop-offs based on how thick the mash is? No rinsing/lautering, just if you soak 1 lb malt in a 2 quarts of water (very thin) at 152F for 60 minutes, you should get be able to get 99% of the theoretically extractable sugars in the malt. And if you soak 1 lb malt in 1 quart of water (very thick) at same temp/time, you can expect to only get 65% of the theoretically extractable sugars...

Something along the lines of:
description | mash thickness | max efficiency
------------+----------------+---------------
very thin | 2.0 | 99%
thin | 1.6 | 95%
average | 1.33 | 90%
thick | 1.2 | 80%
very thick | 1.0 | 65%

If not, it seems like a simple enough experiment to try cheaply at home (small pot and small amount of malt, put it in an oven to keep temp consistent).
Obviously independent variables for different brewers: mill gap, water chemistry, malt choice*, malt freshness...

Bah, forum software doesn't actually do fixed-width font formatting

*Actually, if you're using brewing software for the recipe, it should know the max pts of sugar for each malt, so that's probably not a factor, tho freshness of the malt surely would be...

Yes, there is a chart. I'm surprised you haven't seen it, as I've lost count of how many times I have posted it in different threads on HBT.

Mash thickness does not necessarily affect conversion efficiency, but it does affect rate of conversion, with thick mashes converting more slowly than thin mashes. This can lead to lower conversion efficiency if the mash time is too short for conversion to complete.

Mash thickness does affect the max possible SG of the wort at the end of mash. Go back and read post #22 in this thread for more information.

What is affected by larger beers, which often force thicker mashes, is the lauter efficiency (one of the factors in mash efficiency and brewhouse efficiency.) As the ratio of grain weight to pre-boil volume goes up, the lauter efficiency goes down. This is true for any sparge process: no-sparge, batch sparge, or fly sparge. The reason for this is that with more grain and less liquid, the grain retains a higher percentage of the total wort, and thus a higher percentage of the total extract (sugar, etc.) meaning a lower percentage of the extract created in the mash makes it into the BK - lower lauter efficiency. The chart below is for various numbers of batch sparges (including none) at two different grain absorption rates, and equal volumes for initial and all sparge run-offs.

Equal run-off volumes are used, as that maximizes the lauter efficiency, although the lauter efficiency varies little over the run-off ratio of 60:40 to 40:60 as shown by the chart below from Braukaiser:

A similar effect for grain weight vs. pre-boil volume occurs when fly sparging, and here's a chart that represents that:

Brew on

 

[doug293cz]

One other issue I have with overly fine grinding malt grains is the possibility of extracting unwanted tannins etc from the much more finely ground husks which can very easily happen if water chemistry is out of spec .

Yet another reason to mind your water chemistry. Then you don't have to worry about that. If it was actually a problem with finely ground grain, commercial breweries wouldn't use hammer mills, and homebrewers who BIAB wouldn't crush so fine.

Yes, too fine a crush can cause stuck recirculation in a mash, or stuck lauters, when using a traditional MLT. That's something you have to manage if you use a traditional MLT.

Brew on

 

[Hoochin'Fool]

Yes, there is a chart. I'm surprised you haven't seen it, as I've lost count of how many times I have posted it in different threads on HBT.

I'm embarrassed to admit that yes, I've seen those charts you've posted several times, and they just never sunk in until just now!

Anyways, that efficiency drop-off from lbs-grain-per-gallon does indeed match up very close to my observations (well, 3 different BIAB recipes brewed about 4 times each), and now that I finally see the connection, should be able to get much closer to predicted gravity on the first try.

So thanks, for those simulation charts! And for having so much patience with us dopes out here doing our best to make tasty beer!

 

[doug293cz]

I'm embarrassed to admit that yes, I've seen those charts you've posted several times, and they just never sunk in until just now!

Anyways, that efficiency drop-off from lbs-grain-per-gallon does indeed match up very close to my observations (well, 3 different BIAB recipes brewed about 4 times each), and now that I finally see the connection, should be able to get much closer to predicted gravity on the first try.

So thanks, for those simulation charts! And for having so much patience with us dopes out here doing our best to make tasty beer!

You are welcome. Thanks for the kind words. Doing tech analyses for brewing processes gives my mind a workout now that I am retired. I get a sense of accomplishment when I come up with what seems like a significant result, and even more of a sense of accomplishment if the analysis and explanation helps others understand how things work.

Brew on

 

[RogerGrahl]

My take on adding DME is to not, but it's certainly viable, normal, and etc.

I don't chase a gravity number. I take great care in recording volume and gravity data throughout the making process. By comparing these numbers across batches and throughout a brew, I can find where they 'don't add up' and which numbers are reliable. This has allowed me to find tune my software to the product, not the other way around. By making the software reflect the beer as it is, subsequent beers come out the way I intended with very little effort.

My most recent batch was intended to be 4G VIF @ 1042. It hit 1041 and I just filled 42 bottles. 4G/12oz=42.66

It took me a couple dozen batches to really get my software dialed in, but I'm thrilled with the repeatable results.

This is excellent advice.