### Author Topic: Struggling with formula for converting a recipe  (Read 881 times)

#### Lazy Ant Brewing

• Brewer
• Posts: 444
##### Struggling with formula for converting a recipe
« on: October 17, 2016, 03:37:44 PM »
On previous brewing, I calculated my mash efficiency to be 75%.

I wish to work with a recipe BYO magazine that lists Extract Efficiency at 65% under the recipe standardization headline.

What is the easiest way to do this calculation?

If the recipe begins with:

8.5 lbs pale ale malt
9 oz. roasted barley

What should my values be for those, and how would I derive them?

Could it be as simple as dividing the 65 by 75 and multiplying the result times each of the fermentible ingredients?

« Last Edit: October 17, 2016, 03:48:15 PM by Lazy Ant Brewing »
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#### Stevie

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##### Re: Struggling with formula for converting a recipe
« Reply #1 on: October 17, 2016, 03:52:00 PM »
I typically adjust the base grains only, but yes your formula works.

#### GS

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• Posts: 167
##### Re: Struggling with formula for converting a recipe
« Reply #2 on: October 26, 2016, 04:16:31 AM »
I plug in a recipe exactly as it is written. If the brew house efficency is 65%, I leave it alone.
If not, I take note of the grain percentages in the original recipe, change the brewhouse efficiency in Brewers Friend, then adjust the grain bill to match the original percentages. Problem solved.

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#### Stevie

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##### Re: Struggling with formula for converting a recipe
« Reply #3 on: October 26, 2016, 07:01:56 AM »
That doesn't always work. Let's say you have a recipe written for 75% efficiency. 9lb 2-row and 1lb c40. Convert that to 50% efficiency and you will end up with 1.5lb crystal malt and a much darker beer. Converting isn't always perfectly linear.

#### GS

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##### Re: Struggling with formula for converting a recipe
« Reply #4 on: October 26, 2016, 03:33:10 PM »
If I had to convert to 50% efficiency (because that's what my process gives me), the first thing I would do is take a look at my process, not grain percentages.

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#### Stevie

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##### Re: Struggling with formula for converting a recipe
« Reply #5 on: October 26, 2016, 04:30:24 PM »
If I had to convert to 50% efficiency (because that's what my process gives me), the first thing I would do is take a look at my process, not grain percentages.

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That's cool, just calling out that it doesn't always work using scenarios with simple math.

#### denny

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##### Re: Struggling with formula for converting a recipe
« Reply #6 on: October 26, 2016, 04:42:29 PM »
That doesn't always work. Let's say you have a recipe written for 75% efficiency. 9lb 2-row and 1lb c40. Convert that to 50% efficiency and you will end up with 1.5lb crystal malt and a much darker beer. Converting isn't always perfectly linear.

Wouldn't the increase in pale malt balance out the color increase from the crystal?

ETA:  Just ran your example through Promash.  Decreasing the efficiency from 75% to 50% the color remained the same.
« Last Edit: October 26, 2016, 04:45:09 PM by denny »
Life begins at 60.....1.060, that is!

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#### Stevie

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##### Struggling with formula for converting a recipe
« Reply #7 on: October 26, 2016, 05:13:19 PM »
Did you also increase the grain by 50% to compensate?

Per Beersmith.

90/10 at 1.055 75% efficiency (10lbs total) is 8 SRM. 90/10 at 1.055 50% efficiency (15lbs total grain) 10.6 SRM

The above example is a simple example to show there is a difference. The difference is noticeable with darker malts at relatively small variances. Not to mention the flavor differences caused by larger amounts of specialty malts.

90/7/3 - 2row/40/500 patent - 75% efficiency = 18.5. 70% = 19.4. 60% = 21.5

One can do whatever works, just should understand that it isn't a perfect linear scale.
« Last Edit: October 26, 2016, 05:16:39 PM by Stevie »

#### denny

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##### Re: Struggling with formula for converting a recipe
« Reply #8 on: October 26, 2016, 05:34:03 PM »
Did you also increase the grain by 50% to compensate?

Per Beersmith.

90/10 at 1.055 75% efficiency (10lbs total) is 8 SRM. 90/10 at 1.055 50% efficiency (15lbs total grain) 10.6 SRM

The above example is a simple example to show there is a difference. The difference is noticeable with darker malts at relatively small variances. Not to mention the flavor differences caused by larger amounts of specialty malts.

90/7/3 - 2row/40/500 patent - 75% efficiency = 18.5. 70% = 19.4. 60% = 21.5

One can do whatever works, just should understand that it isn't a perfect linear scale.

Yep, I increased the grain.
Life begins at 60.....1.060, that is!

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"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

#### Stevie

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##### Re: Struggling with formula for converting a recipe
« Reply #9 on: October 26, 2016, 05:41:33 PM »
The something is up with promash. Increasing the amount of a dark grain will change the color if the same volume of water is used.

#### denny

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##### Re: Struggling with formula for converting a recipe
« Reply #10 on: October 26, 2016, 05:44:28 PM »
The something is up with promash. Increasing the amount of a dark grain will change the color if the same volume of water is used.

But if you also change the amount of a lighter grain so the ratio remains the same?
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

#### denny

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##### Re: Struggling with formula for converting a recipe
« Reply #11 on: October 26, 2016, 05:44:56 PM »
The something is up with promash. Increasing the amount of a dark grain will change the color if the same volume of water is used.

Or Beersmith....
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

#### Stevie

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##### Re: Struggling with formula for converting a recipe
« Reply #12 on: October 26, 2016, 05:52:29 PM »
The something is up with promash. Increasing the amount of a dark grain will change the color if the same volume of water is used.

But if you also change the amount of a lighter grain so the ratio remains the same?
No, because the amount of color is not related to efficiency of conversion and even affected by base malts.

Easy examples
100% 2L 2-row - 10lbs at 75% 3.4 SRM, 12.5lbs at 60% 4 SRM
100% 10L Munich - 10lbs at 75% 10.3 SRM, 12.5lbs at 60% 12 SRM

Again, I'm just pointing out that it isn't a simple linear equation to scale every recipe. There is same fiddling that needs to be done.

#### Stevie

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##### Re: Struggling with formula for converting a recipe
« Reply #13 on: October 26, 2016, 05:53:11 PM »
The something is up with promash. Increasing the amount of a dark grain will change the color if the same volume of water is used.

Or Beersmith....
Touché

If I cared enough to try to remember the math, I'd show it by hand as well.

#### hopfenundmalz

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• Milford, MI
##### Re: Struggling with formula for converting a recipe
« Reply #14 on: October 26, 2016, 06:52:51 PM »
A local pro said that the color in Promash is not right. I usually don't care enough to calculate by hand.
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