ABV Calculations on First BIAB and Mash Temp Question

[Ultryx]

I used a refractometer to get my SG post-boil for both my APA and IPA I brewed. These were both my first brews on my new BIAB setup. I just wanted to make sure I am doing these calculations correctly as fermentation has (likely) ended at this point. Both were brewed on 2/15/20.

I used the Brewer's Friend Refractometer Calculator. Let me know if these seem right!

APA
SG: 1.057 (14.02 Brix)
FG: 1.029 --> w/correction = 1.013 (3.29 Brix)
ABV: 5.86% (expected 5.6% via Brewfather)

IPA
SG: 1.058 (14.26 Brix)
FG: 1.034 --> w/correction = 1.020 (5.09 Brix)
ABV: 5.06% (expected 6.3% via Brewfather)

I feel like my APA went really well and I nailed that one. Even squeaked out slightly more ABV. The IPA I let run too hot during the mash. I was supposed to mash at 154 F, but was at around 164-167 F for at least 20 minutes.

Anyway, I could be wrong but I think from what I've learned, that is the cause of my lower ABV. The higher mash temperature made less fermentable sugars and therefore my beer is a lower ABV than I expected. Does that sound right to you guys? Seems unlikely that my fermentation stalled. The APA next to it had zero issues.

 

[McKnuckle]

Yes, without much doubt you are correct. A mash temp between 164-167 for 20 minutes would have denatured beta amylase, and is above the effective working range of alpha amylase as well.

Twenty minutes is a long time. So, whatever conversion happened before temps reached that range was basically all you got. 65.5% attenuation is a reasonable number, given that occurrence.

 

[IslandLizard]

I would urge you to cross check with a (calibrated) hydrometer and make notes of deviations between the 2 depending on the wort or beer being tested.

Aside from calibrating/verifying the refractometer against the hydrometer, it may also shine light on how to refine the "wort correction factor" used in the refractometer calculations.

On a side note, many beginner brewers seem to be overly obsessed about ABV. It doesn't define or describe a beer at all, and has the least of my interest wherever I go (some exceptions noted). I never calculate ABV unless someone specifically asks me for it, or when I need or want to "declare it" when serving at a beer event.

 

[Ultryx]

Yes, without much doubt you are correct. A mash temp between 164-167 for 20 minutes would have denatured beta amylase, and is above the effective working range of alpha amylase as well.

Twenty minutes is a long time. So, whatever conversion happened before temps reached that range was basically all you got. 65.5% attenuation is a reasonable number, given that occurrence.

I figured that's what happened. I should still have a drinkable beer, but hopefully it's not too sweet.

I would urge you to cross check with a (calibrated) hydrometer and make notes of deviations between the 2 depending on the wort or beer being tested.

Aside from calibrating/verifying the refractometer against the hydrometer, it may also shine light on how to refine the "wort correction factor" used in the refractometer calculations.

On a side note, many beginner brewers seem to be overly obsessed about ABV. It doesn't define or describe a beer at all, and has the least of my interest wherever I go (some exceptions noted). I never calculate ABV unless someone specifically asks me for it, or when I need or want to "declare it" when serving at a beer event.

My refractometer is definitely calibrated. Just got it and set it with fresh distilled water prior to all this. Also, the pale ale is right on point where it should be so I'm certain it's all been measured correctly.

As far as the ABV goes that's more for my own knowledge and that's just a result also of doing the calculations of specific gravity/Brix.

 

[IslandLizard]

My refractometer is definitely calibrated. Just got it and set it with fresh distilled water prior to all this. Also, the pale ale is right on point where it should be so I'm certain it's all been measured correctly.

Distilled water is used to calibrate only the null point. 0.00 Brix.
Once you put beer on there it becomes much more complex:

Refractometer Calculator - Sean Terrill

 

[Ultryx]

Distilled water is used to calibrate only the null point. 0.00 Brix.
Once you put beer on there it becomes much more complex:

Refractometer Calculator - Sean Terrill

I'll give your calculator a try when I get home tonight. Should be fairly similar to the Brewer's Friend Refractometer Correction page.

 

[IslandLizard]

I'll give your calculator a try when I get home tonight. Should be fairly similar to the Brewer's Friend Refractometer Correction page.

There's a lot of information on Sean Terrill's page on how the calculator estimates gravity. A wort correction factor of 1.040 seems to work OK generally, but adjusting it may get you results closer to those of a (good) hydrometer, which is the only way to measure gravity accurately. Once you correlate refractometer readings with accurate hydrometer readings you can rely on your refractometer more closely.

Wort is a complex mixture of sugars, so refractometer readings of different wort compositions may/will show (small) deviations from true. Alcohol presence complicates things, while shortening the measuring scale, making estimates potentially less accurate.

Aside from quick gravity measurements pre-fermentation, refractometers can still be very useful during fermentation too. For example, to track fermentation progress one drop at a time, measuring relative changes. As long as consecutive readings drop it's still attenuating.

If and when you decide on buying a hydrometer, stay away from the abundant tri-color scale ones. Get one with a plain white scale measuring only Brix and SG. They may throw in a "potential alcohol scale" for good measure, but it's pretty much useless for most beer. Select one with a scale that's as long as possible. A 1/2 inch extra between 1.000 and 1.100 makes a big difference for more accurate readings. They make precision hydrometers for measuring final gravity, but they're overkill, IMO, and are just as or even more fragile.

Close enough is fine for me. Besides, you really can't change FG once you get there. The bulk of the alcohol is created from OG down to 70-80% apparent attenuation. Diminishing returns from there, down.

 

[bracconiere]

is there a typo in the OP? it say the IPA had a similar OG, but more alcohol....and higher FG?


and everyone knows i love gluco for these situations...

edit: i didn't read it was the prediction, sorry.....i'd still say gluco would get you to around 8%

 

[Ultryx]

There's a lot of information on Sean Terrill's page on how the calculator estimates gravity. A wort correction factor of 1.040 seems to work OK generally, but adjusting it may get you results closer to those of a (good) hydrometer, which is the only way to measure gravity accurately. Once you correlate refractometer readings with accurate hydrometer readings you can rely on your refractometer more closely.

Wort is a complex mixture of sugars, so refractometer readings of different wort compositions may/will show (small) deviations from true. Alcohol presence complicates things, while shortening the measuring scale, making estimates potentially less accurate.

Aside from quick gravity measurements pre-fermentation, refractometers can still be very useful during fermentation too. For example, to track fermentation progress one drop at a time, measuring relative changes. As long as consecutive readings drop it's still attenuating.

If and when you decide on buying a hydrometer, stay away from the abundant tri-color scale ones. Get one with a plain white scale measuring only Brix and SG. They may throw in a "potential alcohol scale" for good measure, but it's pretty much useless for most beer. Select one with a scale that's as long as possible. A 1/2 inch extra between 1.000 and 1.100 makes a big difference for more accurate readings. They make precision hydrometers for measuring final gravity, but they're overkill, IMO, and are just as or even more fragile.

Close enough is fine for me. Besides, you really can't change FG once you get there. The bulk of the alcohol is created from OG down to 70-80% apparent attenuation. Diminishing returns from there, down.

Incredibly detailed post. Thank you! Yeah I actually own a hydrometer too. I thought I was saving myself beer by owning a refractometer since I only need drops of beer instead of several milliliters from the hydrometer method!

 

[bracconiere]

Eat It - Weird Al Yankovic

Incredibly detailed post. Thank you! Yeah I actually own a hydrometer too. I thought I was saving myself beer by owning a refractometer since I only need drops of beer instead of several milliliters from the hydrometer method!

ad an extra cup or two of water to the boil to compensate....

edit: i don't know how "eat it" ended up in this post....

 

[IslandLizard]

edit: i don't know how "eat it" ended up in this post....

I was wondering about that too.
Unless you wanted to be really funny, you must have done a "multi-quote."

To see where it came from, click on the little up-pointing arrow behind "marchuk96 said:" in the quoted segment.
It leads to this post:
https://www.homebrewtalk.com/forum/threads/music-match.32824/page-899#post-8793883

 

[bracconiere]

I was wondering about that too.
Unless you wanted to be really funny, you must have done a "multi-quote."

To see where it came from, click on the little up-pointing arrow behind "marchuk96 said:" in the quoted segment.
It leads to this post:
https://www.homebrewtalk.com/forum/threads/music-match.32824/page-899#post-8793883

i left it in to be funny, that's for sure...but yeah multi quote i didn't know how to delete....lol

 

[IslandLizard]

i left it in to be funny, that's for sure...but yeah multi quote i didn't know how to delete....lol

When clicking on the black [Insert Quotes...] button that appears under your avatar next to the reply box, you can see them. Rearrange or remove before committing to insert them.

You can always edit your posts...

 

[bracconiere]

When clicking on the black [Insert Quotes...] button that appears under your avatar next to the reply box, you can see them. Rearrange or remove before committing to insert them.

You can always edit your posts...

i know, but that would be work...lol, just thought it would be fun to get more music match players

 

[shetc]

Get one with a plain white scale measuring only Brix and SG.

I'm looking for a new hydrometer - can you recommend a model?

 

[IslandLizard]

I'm looking for a new hydrometer - can you recommend a model?

I use a fairly common $8-10 hydrometer from my LHBS. Mine is branded "TRUE BREW." It's pretty decent and good enough for me.

Looks like this, which has the BSG logo on it:

I simply hate those multi-color ones that are included with most kits, they're confusing, hard to read and have a short (compressed) scale. So I carefully selected one that has a simple to read, white scale. It contains 3 scales, SG I use the most, Brix sometimes. The 3rd, potential alcohol %, never, it's useless for beer, and I don't care anyway.

The deviations are easy to read, straightforward, no nonsense. Because of it's fairly long scale, 4" between 1.000 and 1.170, about 30% longer than the crappy multi-color ones, it gives me just enough precision.

Mine is off by 1 point (reads 0.001 higher), so it gets subtracted in my mind. If I break it I hope I can find one that's like it or close. Maybe buy a 2nd for insurance...