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01-02-2013, 03:34 AM   #1
BetterSense
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 BIAB mash efficiency question

I just brewed a batch. Hopville says I got 85% efficiency, but I calculate 60%.

10 pounds of malt gave me 5.7 gallons of wort at 1.053 or 13.0 plato.

My calculation: (21 kg of wort)(13% plato) = 2.73 kg of extract = 6.0 lb extracted.

6lb extract from 10lb of grain would be 60% mash efficiency. Is this correct?

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01-02-2013, 04:42 PM   #2
alestateyall
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That is not the correct efficiency equation. Efficiency is the percent of available sugars (in gravity points per gallon [PPG]) that you extracted.

Sugar has 46 PPG.
Two Row has 37 PPG.
All malts and other fermentables have PPG values.

If your brew was all Two Row then your available sugars were 37*10/5.7=64.9 PPG. If you have more than two row each grain contributes to the available PPG by adding its available PPG times its weight divided by the total volume.

You achieved 53 PPG (OG*1000-1000).

Your efficiency is 53/64.9 = 0.816 = 81.6% (assuming all two row malt). Your higher number suggests other malts in the grain bill or the other tool assumed a smaller volume. Lots of tools use the target volume when calculating efficiency which is only correct if you actually ended with the target volume.

Sounds like a good days work.

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01-02-2013, 06:17 PM   #3
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The grain bill was 10lb of weyermann vienna crushed at LHBS and mashed at 68C for 1 hour stirred occasionally, not mashed out and not sparged. I originally got 1.060 in the fermenter but diluted back to 1.053 at 5.7 gallons.

I suspected that I was calculating efficiency wrong. Doing it my way, 100% efficiency would mean the entire grain, husks and all, would dissolve, obviously I need the PPG values in order to calculate efficiency the way everyone else does. Where can I find those PPG values for different malts?

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01-02-2013, 07:14 PM   #4
alestateyall
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Use the last 2 digits from the potential SG column on this chart.

http://beersmith.com/grain-list/

Alternatively, if you know the grain's extraction percentage from the manufacturer multiply that number times 46 (the PPG for table sugar). Extraction percentage values are typically in the 70-80% range.

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01-02-2013, 07:19 PM   #5
alestateyall
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PS. You can measure efficiency before or after dilution. Just make sure you divide by the volume of the wort you used measure the specific gravity.

I have read here in HBT that it is better to measure before dilution because you need to stir a long time to get an accurate specific gravity measurement after dilution.

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01-02-2013, 09:39 PM   #6
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Quote:
 Originally Posted by kehaar Alternatively, if you know the grain's extraction percentage from the manufacturer
I would rather know that, because I avoid using lobotomized units (i.e specific gravity) for brewing. I can back-calculate extraction percentages from the PPG info, but does anyone know of a more generic chart or guide for extraction percentages (e.g. lab efficiency)? Can I just assume 80% for base malt, 75% for toasted malts, etc?

Weyermann lists the extract % of their vienna at 79% in the datasheet on their website.

My new calculation: (21 kg of wort)(13% plato) = 2.73 kg of extract = 6.0 lb extracted.

6lb/[10lb(.79)lb] = 76% which sounds reasonable.
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01-02-2013, 10:12 PM   #7
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Your efficiency is effected by your equipment and brewing process. Once you have a few batches with consistent numbers you can plug your efficiency into the recipe SW.

Each grain has a different potential points per point. In general darker = more adjunct and less conversion.

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01-02-2013, 10:33 PM   #8
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Does anyone know how to convert from PPG into lab efficiency (extraction %)?

That beersmith list is really great, but I'm not sure how to convert.

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01-02-2013, 11:04 PM   #9
alestateyall
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Quote:
 Originally Posted by BetterSense Does anyone know how to convert from PPG into lab efficiency (extraction %)? That beersmith list is really great, but I'm not sure how to convert.
Do you work at TI? I used and lived in Richardson, TX.
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01-02-2013, 11:22 PM   #10
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Yeah I work at TI. Nobody here knows how to convert from PPG to lab efficiency extract %; go figure

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