ABV low

Post #1 made 9 years ago
Hi!
I have completed about 5 or 6 BIABs now, and currently I'm working on my ABV readings and calculations and I feel like I have been coming up short on the ABV readings. For example, here are the numbers from my last batch:

Target volume was to be 10.5 gallons into fermenter, but my boil loss calculations were off and I ended up with 9.25 gallons into fermenter. We decided not to add water and simply assumed everything was going to be more concentrated, which would make a greater ABV.
Target post boil OG = 1.050
Actual OG = 1.057, I assume I met my target OG and surpassed it because of the higher concentration.
Target FG = 1.011
Actual FG = 1.022
Target ABV = 5.11
Actual ABV = 4.59

Fermented around 68 degrees for 10 days according to recipe. Bubbling had stopped. All hydrometer readings corrected for temp. Wort was aerated into primary by splash-pooring.

Since I was expecting a higher ABV than the recipe and ended up with a lower ABV, I have two concerns. Are my assumptions correct... do I understand how all of this is working? If so, then why am I not reaching fermentation targets?

Thanks!
Jeff

Post #2 made 9 years ago
vonBobo wrote: All hydrometer readings corrected for temp.
What was the temp when you took the first reading? Was it hot?

MS
Last edited by Mad_Scientist on 16 Apr 2015, 03:52, edited 1 time in total.
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Post #4 made 9 years ago
What temp did you mash at? Fermentability is greatly affected by mash temperatures......

---Todd
WWBBD?
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Post #5 made 9 years ago
.... as well as the yeast & its viability.

It could be due to what Todd has mentioned, or even yeast type.
I am guessing you expected the yeast to attenuate to 77% based on the targets, however, you got 60%!
What yeast did you use? was it pitched from packet or did you use a starter? Out of date? Just some other things to ponder.
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
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Post #6 made 9 years ago
Jeff, the first thing I am going to say is that you need to acknowledge prior posts. For example, I wrote a reply to you here that would have taken me a good 30 mins or more to write but I received no acknowledgement that what I wrote helped you.

I think I could help you really well in your question above but it would take me at least 3/4 of an hour. I know you, as a new brewer, get enthusiastic and run out of time but, I think, when I don't get a response from prior answers, that my answers are not in the style you need :).

Here is the short answer though that you do need...

If you don't want to waste your time (and ours) you need to learn the BIABacus and use it. It will, in as short as time as possible, narrow down any brewing fault. Very few, if any, brewing faults can be determined after one brew. ABove you offer one brew with vague figures that are not confirmed on the brew let alone by other brews.

The posts above are correct but there are a hundred more questions that could be asked and until you provide and record enough detail on your brews, these questions are just guesses at what your problem might be.

Do the due diligence, record the right numbers (as the BIABacus asks) on a few brews and then we can talk.

For now, all we conclude is... nothing.

EDUCATORS HERE

MS, thughes and myself can't be expected to be on the ball 24 hours a day. One sentence answers are hardly ever any good so please direct Jeff to any posts that will help with....

1. You can't trust single measurements on a single brew.
2. Common causes of a low efficiency reading.
3. There must be heaps of other essays written here on the relationships between gravity and volume. Maybe search "Gravity Points"

Please pass the info or links on.
Last edited by PistolPatch on 16 Apr 2015, 19:57, edited 1 time in total.
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Post #7 made 9 years ago
Thanks everyone for your replies.

Mash temp was 154, mash ended at 45 minutes and temp was 152. (I was worried about this to begin with... maybe this was for 3v system where a 15 minute sparge was assumed and not listed??? Is this where the iodine test would be helpful?)
Yeast was Wyeast Northwest and Wyeast American Ale (two primaries were used). Yeast was within date, smacked about 5 hours before pitching and swelled the usual amount, and also passed the "smell check".

I apologize for running off on that prior thread. I didn't post it with enough time before my brew day and my LBS ended up performing the calculation for me.

Post #10 made 9 years ago
I think this is really an attenuation question.

One of my last beers didn't attenuate good. I chalked it up to too cold of fermentation temperature and rehydrating dry yeast a wrong way, as my mash temperature was never much above 150F at any length of time. So for me, I felt I did everything right on the hot side of things (sweet wort production). It's really frustrating for sure with 10 gallons of finished sweet beer. :argh:

Could your mash temperature have spent quite a few minutes above 158F, which would have allowed the alpha amylase to make long
sugars that were un-fermentable?

MS
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Post #11 made 9 years ago
VonBobo, looking over the BIABACUS file you ended up with 40.75L of VAW, where as the Projected volume was 46.31L.

That difference may have given you 1.057Sg instead of the 1.050Sg Projected.

The recipe used 68 parts of Pale Ale, and 32 parts of stewed Grains, or 32% of the grain bill has been pre-heated.

The Caramel, carapils, Munich, and Chocolate malt will give a lot of Body, and a lot of Un-fermentable Sugars.

This may be Part of your 11% lower ABV than desired.

This Must be a nice Dark, slightly Sweet, Brown Ale.
Honest Officer, I swear to Drunk, I am Not God.
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Post #12 made 9 years ago
Mad...
Well, the hot liquor started at 160f to balance the incoming grain at 70f. Im sure it spent a few minutes above 158. But I was under the impression this was standard practice?

I also thought the high wort mark for preventing long chain sugars was 170?

Where do I go to find fermentation temps? The recipe will say one temp, the yeast package (same from recipe) will say another temp, then the old timers talk about a range of temps they utilize throughout the fermentation process for each type of beer, each degree processing a different flavor profile in the beer. Confusing!
Last edited by vonBobo on 17 Apr 2015, 04:43, edited 1 time in total.

Post #13 made 9 years ago
joshua wrote:VonBobo, looking over the BIABACUS file you ended up with 40.75L of VAW, where as the Projected volume was 46.31L.

That difference may have given you 1.057Sg instead of the 1.050Sg Projected.

The recipe used 68 parts of Pale Ale, and 32 parts of stewed Grains, or 32% of the grain bill has been pre-heated.

The Caramel, carapils, Munich, and Chocolate malt will give a lot of Body, and a lot of Un-fermentable Sugars.

This may be Part of your 11% lower ABV than desired.

This Must be a nice Dark, slightly Sweet, Brown Ale.
Correct, it is a Fat Tire clone- Amber Ale.

The 68 base/32 body ratio is the same as the recipe I got it from, but their calculation for the ABV is much higher than what I ended up with.

My assumption was the same about the VAW, I had a lot less wort after the boil than I calculated so of course the wort is more concentrated. So I assumed I had met and exceeded my target OG... aside from the higher concentration that everything went "ok" with the mash. So then after fermentation I was expecting a higher concentration of alcohol, but ended up with a lower ABV than even the recipe called for. That is why I am thinking I have a fermentation problem?

Jeff
Last edited by vonBobo on 17 Apr 2015, 04:36, edited 1 time in total.

Post #14 made 9 years ago
Jeff, The only Problems I have had with Fermentation is Not enough aeration,and Too Low temperature for the Yeast.

If you know your Thermometer is right on, and you poured/re-poured, stirred or Used Pure O2, Then I believe the 70/30 grain Bill has given you a lot of Body, and lower ABV.

You may have a Fat Tire Clone - Light Porter.

Which should be a good beer. Let us know how it finishes!!!!
Honest Officer, I swear to Drunk, I am Not God.
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Post #15 made 9 years ago
Q&A #1
I can see that in the BIABacus Section X, if the strike temp factor is set to "5" (for thin walled electric urns) and the grain is at 70F, then the strike temp does say 160F. In that scenario the temp should settle out rather soon. If your mash didn't settle into 154F in a small amount of time, then maybe revisit that adjustment factor again on your next brew.

Q&A #2
This is a good BYO article I have bookmarked; https://byo.com/videos/item/1543-unders ... ew-science

#3 - confusing indeed...there is a range of temps. I would definitely be in the middle for the first 5 days (70F) and then raise it to the high end for the next 5 days (75F), for https://www.wyeastlab.com/hb_yeaststrai ... cfm?ID=139.

MS
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Post #16 made 9 years ago
PP may chastise me for this but I will always err on the side of caution and go with a strike temp that is a few degrees less than indicated by the calculations. I can always add a bit of heat (however slowly) but trying to cool the mash down quickly is difficult and usually involves adding cold water (which then throws all of your volumes off). YMMV.

---Todd
WWBBD?
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Post #18 made 9 years ago
Jeff, I felt bad about my last post here even though I still have not had time to re-read it.

Pretty pleased though that on a quick scan you and others have been tolerant of what I wrote and maybe it even did help :think:.

As mentioned, I still haven't had time to re-read the whole thread but I hope that we are not fretting over one brew. If there really is a low attenuation problem then you need to go back to thughe's first post here before you consider anything else because even that one question has a lot of sub-questions!!!

I'm drunk now so that is all I have to say apart from the fact that thughes is perfectly right in #16 above.

Good job Todd :thumbs:.
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Post #19 made 9 years ago
Also, give a try to 90 minute mashes. If you see no difference then carry on as normal, but we would always recommend 90 minutes.
There may be no starches at 45 minutes (iodine test seems OK), but you may still have long branched chains (amylopectin, amylose, dextrins etc.) which will affect attenuation.
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
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Post #21 made 9 years ago
mally wrote:Also, give a try to 90 minute mashes. If you see no difference then carry on as normal, but we would always recommend 90 minutes.
There may be no starches at 45 minutes (iodine test seems OK), but you may still have long branched chains (amylopectin, amylose, dextrins etc.) which will affect attenuation.
That is one of the new things we tried this past weekend actually, but of course we didnt nail it this time either. We got a 1.062 post boil OG and we were just a half gallon short in a 10 gallon batch (target was 1.05). Could that half gallon made that much of a difference? Are there calculators to help determine the ABV if I add a bit of water?
Last edited by vonBobo on 20 Apr 2015, 11:59, edited 1 time in total.

Post #22 made 9 years ago
A completed BIABacus would certainly tell you where you deviated from normal.

Are you saying you expected 10 Gallons @1.050, but ended up with 9.5 Gallons @1.062?
If so, you could dilute back to 10 Gallons and you should end up with 10 Gallons @1.059.

Without knowing any more details, it is impossible to tell where this deviation occurred though.
Last edited by mally on 20 Apr 2015, 14:58, edited 1 time in total.
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
    • SVA Brewer With Over 100 Brews From Great Britain
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