High mash temperature and effects on alcohol %

If a mash was subjected to higher temperatures causing more unfermentable sugars and the resulting final gravity of that beer would be much higher than anticipated, would that cause the alcohol to be reduced as well? The reason I ask is because the amount of fermentable sugars shouldn't have changed as temperatures in the higher ranges will also release fermentable sugars at the same rate. So if my final gravity is stuck at 1.035 can I assume that the alcohol content is higher than calculated?


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I believe it will be lower..What was the OG?

 

1.057 OG target FG 1.015



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I use this calculator http://www.brewersfriend.com/abv-calculator/

Looks like your ABV will be 2.89%

If you hit 1.015 it would be 5.51%

 

Unfermentable sugars add to the gravity correct? If they do then wouldnt that add to the final gravity but at the same Time the fermentable sugars which should've produced at the same rate during the mash if it was at 150F. Those sugars should've been converted into alcohol in their entirety causing a higher final gravity but the same alcohol percentage.


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"Unfermentable" means that the yeast can't break them down to alcohol. Fewer fermentable sugars would mean a lower alcohol content and a sweeter tasting beer.

 

My last brew that I bottled today had a mash temp that got away from me while I was not paying attention. It went up to around 165 or a bit higher before I caught it. It was only about 10 deg higher than the 156 mash temp I wanted but I was worried. OG was 1.063 and I ended at 1.012 so it worked out for me with roughly a 7% ABV

 

Thanks for the definition....


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Attenuation effects maybe?


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my issue was a location/failure of a gauge and I believe the entire batch was mashed very high. I hit OG though so enzyme activity wasn't detrimentally effected.


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Your OG is based on all the sugars you extracted during your mash, fermentable & non- fermentable.
With the high mash temp you pretty eliminated the beta amylase activity and probably the alpha amylase activity was at best limited.
All of this wi give you a good OG but the yeast cannot convert it to EtOh and CO2, ie, alcohol. Thus, even though your OF was good your FG was diminished because your yeast had less fermentables.

 

This is absolutely correct, there Isnt additional sugars created at the higher temp, the existing sugars just aren't broken down completely so they never ferment into alcohol in the first place...

 

In the book homebrewing engineering I thought there was a series of graphs at various temperatures and all of them showing the alpha rate staying consistent with the beta rate obviously increasing with increased temperature. Obviously I'm missing something


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That could be what I'm missing. I was under the impression that both were present


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Thanks guys I need to go back and reread something but in the end it looks like I have a low Alcohol percentage beer no biggie, just trying to understand it a little better.


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The beta amylase works best at lower mash temps and the alpha at higher. There is a range, the brewers window, which is best for both.
That being said, the OP, far exceeded the effective temp range for both.
He did get some activity as the denature get process isn't instantaneous but he certainly missed the "window"!

 

I had a similar issue. Mashed a bit low 148F thinking my og would be a bit higher then did a 169 batch sparge for 15 minutes. Ended with og 1.086 but then its stuck at 1.036.. Not sure if its unfermentable or under pitched and Im thinking repitch... What do u think?

 

The graphs on page 44? I guess it's a little hard to tell, but the slopes are different. The fermentability results on page 46 might demonstrate the difference better.

 

Maybe this will help.

 

Thank you


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Yes it was page 44, just got back home and pulled it out.


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Woodland love your book, I must have interpreted the graphs incorrectly. Tough to remember everything out of every book you read and my minds eye failed me. Thanks everyone for straightening me out a bit. I just finished my 6th all grain batch and I'm hoping the bugs have been worked out of my system.


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I'm still trying to get all the bugs worked out of my brew system, and I've been brewing since 2009

 

Thanks! I'm glad you have enjoyed it. One of the things I like most about brewing is that there is always something to tweak.