Author Topic: Struggling with formula for converting a recipe  (Read 769 times)

Offline Lazy Ant Brewing

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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?

Thanks in advance for your help.
« Last Edit: October 17, 2016, 03:48:15 PM by Lazy Ant Brewing »
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Offline 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.

Offline GS

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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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Offline 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.

Offline 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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Offline 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.

Online 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 »
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Offline 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 »

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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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Offline 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.

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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?
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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!

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Offline 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.

Offline 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.

Offline hopfenundmalz

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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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