ABV vs Attenuation

[Johnson1522]

As a first time brewer, I'm probably way more involved in the process than I should be. I want to measure / smell / taste / poke...my beer. Even with the possibility of contamination or oxidation, I think it's more important to really learn and understand the process than brewing a knock out beer on my first try. There WILL be others...

So here's the info. I'm 10 days in to primary fermentation of an extract kit hefeweizen. All 10 days have been at 65-66 degrees.

My OG was higher than expected. IF my measurements are right, a fully fermented beer could be almost 6% ABV. Currently, I'm tracking about 4.7% with 43% attenuation. The yeast claims a rate 73-77%.

My questions revolves around which measurement is more important. Will a higher than desired ABV have any noticeable effects? (Other than the obvious) Will it affect taste, conditioning, etc?

I'm guessing the only way to stop the process is by flash cooling it and letting it settle for a week to settle and clear? How would that affect conditioning/taste?

 

[frazier]

I applaud your intention to learn as much as possible from your early brews. I remember my first brew, I think I took 10 gravity measurements between pitching and bottling. Now I take two, but still my overall grasp of the process benefitted from all that excess attention.

Anyway - the first thing to realize is that once you pitch the yeast, you are no longer in control. The yeast has taken control, and you must wait until it is finished. For ABV, you get what you get. Don't even think about trying to halt fermentation early - that road leads to madness, or at least frustration.

It sounds like you started with an OG of 1.060 or thereabouts, and 75% attenuation will get you 6% ABV and an FG of around 1.015. Continuing with my WAGs, 43% attenuation has your gravity at 1.034, which seems rather high for 10 days of fermentation. You should be closer to FG, I would think.

You said your OG was higher than expected - what did you expect? How much extract was in the recipe? Did you aerate the wort? Tell us more about your recipe and process.

Cheers,

 

[Johnson1522]

It sounds like you started with an OG of 1.060 or thereabouts, and 75% attenuation will get you 6% ABV and an FG of around 1.015. Continuing with my WAGs, 43% attenuation has your gravity at 1.034, which seems rather high for 10 days of fermentation. You should be closer to FG, I would think.

My thoughts exactly. At first, I attributed that to a lower temperature but everything I'm reading suggests that 65-66 is an ideal temperature.

The extract kit suggests a 5% abv. Of course, it's entirely possible that my measurements are inaccurate. The more I think about it, the more likely it seems. The first measurement was taken at 81 degrees right before I pitched my yeast and I was careful to adjust for the temperature. I did NOT aerate other than a few brisk stirs before I pitched.

 

[ACbrewer]

what was your recipe? Grain or Extract?

 

[Johnson1522]

It's an extract kit.

 

[looneybomber]

I did NOT aerate other than a few brisk stirs before I pitched.

Normally you want to aerate quite a bit prior to pitching yeast. The yeast need O2 for reproduction.

 

[Johnson1522]

I didn't aerate this round because I was told that Hefeweizen didn't need to be aerated much. If there's one thing I've learned so far, it's that each question has 10 different answers that take me in 20 different directions.

Thanks for the tip. I'll give it a shot next time and see how things turn out.

 

[JeepDiver]

It is really hard to get a real good mix with extract and top off water if you don't do a full volume boil. You probably got a bad OG reading. Unless you have less volume, it is impossible to get a higher OG than expected with an extract kit.

 

[rklinck]

If this was an extract kit and you hit your final volume, you should have hit your OG. Did you boil the entire volume of liquid or did you top off with cold water? If you topped off with cold water, your OG reading was probably wrong because you did not get the boiled wort and the top off water fully mixed before you pulled the sample. There are many threads on here about that. Don't worry, it will mix itself up during the fermentation.

For your broader question, I would not worry about trying to calculate ABV as you go. The better route (and one that would be clearer for everyone here to provide advice) is simply to take the gravity readings as things move along. Once the gravity stabilizes for multiple days in a row, you have hit FG. You can calculate your ABV of the finished beer at that point. With that in mind, what was the OG you measured and what was the last gravity reading?

To help with your particular issue, what yeast did you use? If it was a dry yeast, aeration is not the issue. Although Aeration is not a bad thing for dry yeast, it is not nearly as important as for liquid yeast.

 

[Johnson1522]

II topped off with water but I feel like I stirred it pretty well. It was a dry yeast. Fermentis WB06.

My OG was just under 1.060. Currently, I'm right at 1.025

 

[rklinck]

II topped off with water but I feel like I stirred it pretty well.

This is what EVERYBODY says when they post on here worried that the OG was off on their first extract brew. Your OG was probably close to what the kit said it should have been (assuming you topped off to the right volume).

EDIT: Here is a thread from Revvy (a wonderfully helpful commenter here) about this topic: https://www.homebrewtalk.com/f39/at...inal-gravity-reading-wrong-dont-panic-289735/.

I don't understand how you arrived at your 43% attenuation. If your OG was 1.060 and your current gravity is 1.025, you have gotten 58.3% attenuation. You figure attenuation based on the gravity points (not the whole gravity reading). Here you are trying to figure out how much of the 60 points of OG you have turned to alcohol. You have converted 35 of the 60 points to alcohol, so attenuation is 58.3% ((60-25)/60).

Be aware that a lot of extract brewers have their brews stall at about 1.020. Lots of theories out there on why this is, but you may be getting close to FG.

 

[Johnson1522]

So it seems like I've done some backwards reading on my attenuation. Thanks for pointing that out!