Author Topic: How beersmith 2 computes estimated ABV?  (Read 468 times)

Offline virtualpaul

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How beersmith 2 computes estimated ABV?
« on: February 05, 2020, 09:00:40 AM »
I am trying to design a beer based on one I already did in the past.

I am using the last release of BeerSmith 2.

1- I see the 'Est ABV' displayed but if I remove the mash step 'saccharification 1 beta amylase'  and just keep the mash step 'saccharification 2 alpha amylase', the 'Est ABV' does not change and I am wondering why?  What is the proper way of changing the ratio alpha/beta amylase (non-fermentable/fermentable sugars)?

2- Also, after I removed that mash step, I closed the tab for that beer without saving but it seems to have saved it anyway.  Is this normal?  I would prefer if I could decide when to save.  Is there an option for this?

Offline Oginme

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Re: How beersmith 2 computes estimated ABV?
« Reply #1 on: February 05, 2020, 01:56:16 PM »
It would be nice to know what the steps actually were.  Without knowing what temperatures rests were removed, it is hard to comment on why the change did not alter the ABV.

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Offline virtualpaul

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Re: How beersmith 2 computes estimated ABV?
« Reply #2 on: February 05, 2020, 03:51:50 PM »
There was a lot of step...

So I duplicated another simpler recipe with only two mash step.
40min at 145F
40min at 158F
Beersmith shows 5.5% Est ABV.

When I keep only this (removed the other one):
40min at 158F
Beersmith shows 5.5% Est ABV.

When I keep only this (removed the other one):
40min at 145F
Beersmith shows 6.8% Est ABV.

Offline Oginme

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Re: How beersmith 2 computes estimated ABV?
« Reply #3 on: February 05, 2020, 04:59:00 PM »
OK, so here is what is happening

BeerSmith 2 has limits on the mashing range to match the gelatinization temperature  of starch runs from 59C (138.2F) to 63C (145.4F).  This limit means that it ignores the affect on wort fermentability for mash temperatures below 146 F.  It then takes the next temperature in the saccharification zone (158F) and uses that to calculate out the fermentability of the wort.  So when you erase the lower saccharification rest, it does not affect how the program calculates mash fermentability and thus no change in the predicted FG and therefor no change in the ABV.  When you remove the rest in the saccharification zone, it defaults to the lowest fermentability of wort calculation which then gives you a lower FG/higher ABV.

This range was expanded in BeerSmith 3 at the request of many users.

The other factor at play is that there is no good model for multiple saccharification rests.  Too much depends upon what temperature rests are used and how much time is spent at each rest in order to develop a reasonable estimation model for fermentability.  Thus, most models use the first temperature rest within the saccharfication zone.  I do not know if other programs put caps on the zone like BeerSmith does, but they will give users the idea that they can achieve unreasonable results if they do not.
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Offline virtualpaul

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Re: How beersmith 2 computes estimated ABV?
« Reply #4 on: February 17, 2020, 07:14:56 AM »
Thanks for your detailed answer.

I tried to change the 145 to 146.1 and added a 'bogus' mash step of 1 minute to make sure there was something but got the similar results:

40min at 146.1F
40min at 158F
Beersmith shows 5.5% Est ABV.

1min at 146.1F
40min at 158F
Beersmith shows 5.5% Est ABV.

40min at 146.1F
Beersmith shows 6.7% Est ABV.

Is there a way to make this work?

Also I am still wondering how to prevent beersmith from automatically saving any changes I make.  I like to edit a recipe before I 'save as' but get screwed every time since it 'scraps' my original recipe when I do this.
« Last Edit: February 18, 2020, 09:11:43 AM by virtualpaul »

Offline Oginme

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Re: How beersmith 2 computes estimated ABV?
« Reply #5 on: February 18, 2020, 09:37:42 AM »
The way to exit out of a recipe without saving any changes is to click on 'cancel' right next to the 'OK' button.

With regard to your estimation of ABV, I cited in my first response that there is no good way to estimate the fermentability of multiple rests within the fermentability range.  I think you are looking to a definitive answer to a model which does not have the distinction to give you exacting results.  The actual estimation of final gravity is very much dependent not only upon the fermentability of the wort, but also the health of the yeast, the strain of yeast used, fermentation temperatures, oxygenation of the wort prior to pitching the yeast, cell count of the yeast, etc.  There are just too many factors that end up making small but inevitably significant differences in how much sugar gets converted into alcohol.  The fermentability of the wort can also be affected by the age of the grains and storage conditions, the amount of enzymes present and ratio of base malt to adjuncts, unfermentable dextrins in the specialty malts, etc. 

In the end, until you actually brew your beer using the steps you want will you really know the true ending gravity and ABV.  Doing a forced fermentation test on a quart of wort will give you a target based upon the best possible fermentation you can achieve from that given wort so that you can identify the affects of other fermentation factors.
Recycle your grains, feed them to a goat!

 

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