Attenuation graph

I am looking for graphs that show, for a given yeast and a given OG, what the gravity is each day throughout fermentation. I know I've seen these but I can't find them now. Any help?

How accurate are those graphs? I know I would rather make my own since it's very dependant on brewhouse standards. How many ppm of o2, temperature-curves, viability and pitching rate.

I think I'd be more confused by trying to compare my beer to a (what to me seems like) a generic chart.

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Well the reason I'm asking is I'm wondering what the general curve of the graph looks like. I made a 1.075 OG double IPA which BeerSmith told me would end up at 1.010. Here are the gravities I have taken:

1.075 OG (day 1)
1.040 (day 3)
1.030 (day 4)
1.022 (day 5)
1.020 (day 6)

So I'm wondering if it's normal for a slow creep up to the terminal gravity and I should expect a 1.010 end, or if I should crank up my temp a bit because it likely won't get to 1.010.

Tell us more about your recipe, brewing method, yeast, and temps.

It's logarithmic. So, the SG will drop after at the beginning than at the end.

You have about 85% of your anticipated attenuation. I would think you could increase the temp a little without ill effects. Many off flavors are made early in the fermentation.

So do you think I'll get to 1.010? Will a beer that only crept 2 points (from 1.022 to 1.020) make it all the way down to 1.010?

I usually see a slow creep towards the end of fermentation that takes about as long to attenuate as the initial "bulk attenuation." If you want to to help the yeast out a bit, feel free to increase the temperature a bit (only if it's currently towards the low-end of the recommended ferm. temp.) and swirl the bucket/carboy a bit to put that yeast back into suspension. One thing to note, is the yeast strain plays a big role in this. Yeast that is highly flocculant (meaning it will leave the beer clearer, faster) is generally less attenuative by itself. That's not to say that it can't attenuate all the way, it just needs help getting back into suspension to finish the job.

If the gravity only made a 2 point jump in a day and your current gravity is 1.020 then it sounds like your yeast is about done and probably won't reach your target gravity. Did you make a yeast starter?


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If you get 75% attenuation on a 1.075 beer, that's a FG = 1.019.

What you are hoping for is about 87% attenuation. Getting attenuation that high is going to be recipe, mash temp, and yeast dependent.

1 - you are not going to get to 1.010.

2 - beersmith doesn't know what you are brewing, and is only as smart as the information you give it. FG per beersmith us only an estimate.

3 - if you really want help, post recipe, yeast, and temp. Apart from you saying BS says you should get 1.010, we have nothing to sayvif that is realistic or not.

From 1.075 to 1.020 is 73.3% attenuation.

That's typically what I get when using something like WLP002 (English Ale Yeast). WLP001 or WLP007 usually get me into the mid 80% range.

What yeast did you use and what was your mash temp? Mashing in the 145 to 147 range for 90 minutes usually gets me higher attenuation as well.

Hey guys, thanks for the responses. Here's the recipe:

34 gallon batch.

84% Pale
7.5% cane sugar
6% Carapils
2.5% Crystal 40

Mashed at 150F.
Servomyces in boil.
Safale US-05. Rehydrated yeast before pitch.

1.075 OG. Pitched at 18C (64.4F).
2 days after pitch: Set to 19C (66.2C). [didn't take a gravity]
3 days after pitch: 1.040.
4 days after pitch: 1.030, set to 20C (68F).
5 days after pitch: 1.022.
6 days after pitch: 1.020, set to 22C (71.6F).

Thanks!

you really have 2 options, just like anyone else who doesn't get there finishing gravity. heat the fermentor to 77deg or add more yeast. heating it up is by far the easiest. if heat doesn't work do a force fermentation test to find out if your yeast has lost viability/vitality. next time don't add any refined sugar as this can cause the yeast to consume just the sugar then stop and not consume the more complex sugar from the pale malts

one other thing I've noticed is that sometimes the LHBS doesn't store the dry yeast properly, if the yeast is not stored in the refrigerator than the expiration date is only 3 months from the manufacturer date.

I would think the complete fermentability of the sugar would be countered by the unfermentability of the Carapils. 150F is kind of middle of the road for mash temps. So I would guess a middle of the road attenuation ~ 75% - 78%.

So, I'm thinking with a little coaxing, you might get to ~ 1.015. But it wouldn't surprise me if it stopped at 1.018.

Beernik said:

I would think the complete fermentability of the sugar would be countered by the unfermentability of the Carapils.

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unfortunately it doesn't really work that way, yeast will ferment glucose from the refined sugar with almost no effort. then it will either stop or switch gears to ferment the maltose from the 2row pale malt. if the yeast has decided to stop you will have to put more yeast in to restart the fermentation. yeast will completely ignore unfermentable sugar.

Nice. You tell me "it doesn't really work that way" and then go on to explain how it works that way. Let me clarify...

7.5% of a grain bill that is 100% fermentable + 6% of a grain bill that is 0% fermentable is a lot like having 1.5% of a grain bill that is 100% fermentable.

Of course, it's not going to be quite that even. Table sugar is ~ 42 ppg. Carapils is ~ 33 ppg. So it will ferment like having more than 1.5% of the grain bill being sugar, but not a whole lot more. I'm coming up with ~ 2.8%.

The bottom line is you can't expect the sugar to drop the FG much lower than if the recipe was all malt.

If Safale-05 normally gives 78% attenuation, seanppp shouldn't expect much more than 78% attenuation. (78% is what BrewPal gives me for the yeast. I don't know how accurate that is.)

sorry, I wasn't trying to be rude, I obviously didn't understand what you were trying to say. I don't think you understood what I was trying to say.

what I'm getting at is the biological property of yeast. yeast, being temperamental, can't allays be put into an equation and expect the same results. If they feed on simple sugars it can be hard for them to switch to more complex sugars

as I read more about it I don't think this would be the issue here. table sugar is sucrose. Glucose is the sugar that can cause problems.

Well, I guess the real question is how can I avoid this happening again (assuming the same grain bill). My recipe was based on the Pliny grain bill (though I upped the Carapils and lowered the Crystal, but the sum of those two is the same), and they get the attenuation that I was wanting.

I added servomyces, oxygenated, and rehydrated the yeast, so I'm thinking it was maybe my temperature program.
-1.075, pitched at 64.4F
-1 day: 64.4F
-2 days: Set to 66.2F
-3 days: 1.040, 66.2F
-4 days: 1.030, set to 68F
-5 days: 1.022, turned off cooling
-6 days: 1.020 (terminal), still 68F (never got warmer after turning off cooling)

It seems to me like it mowed through the sugar pretty well during the first 4 days, which is great, but maybe I should have done this:
-Pitch at 64.4F
-1 day: Set to 66.2F.
-2 days: Set to 68F
-3 days: 68F
-4 days: Turn off cooling.

What do you think?

34 gallon batch? Is that correct? How much and how viable was the yeast used?

Yeah. 34 gallon batch. I used the Mr Malty yeast pitching calculator to determine the pitch.

I have never had BS or Brewtarget guess my FG correctly, usually they are high by 2-5pts. I have resigned myself to thinking my system is just too different from whatever ideal BS has in mind.

Now that I read your batch volume I suspect my advice is less valuable than your experience, but some heat (up to maybe 74?) would seem to be in order.

Your temps are right in line with what I do for 05. I think the advice to warm it up a few degrees is good, and rouse the yeast. Is it possible your thermometer you used for the mash needs to be calibrated?

These kinds of posts make me think that the person's mash temp may have been higher than they think, or insufficient aeration.

Mash temp issues are my go-to for high FG because incomplete conversion is easy to do if you don't get adequate mash circulation and even denature some of the mash early on if it's fired. You can sometimes pitch in totally unaerated wort and get good attenuation, eventually. You won't get that from semi-converted wort, ever. Just my first hunch, though.

To get that much attenuation, I'd drop the Carapils. If you want +80% attenuation, any Carapils is going to be working against you.

Add a flaked or a torrified grain if you are worried about head retention.

It was pointed out earlier that that adding simple sugars inhibit yeast from completely metabolizing maltose in wort. A while back I came across this academic paper describing this phenomenon. Perhaps, as one poster pointed out, sucrose is less problematic than dextrose which is what I use. In the future, you might consider an approach that works for me which is to add the sugar as a sterol syrup near the end of fermentation. I have regularly fermented a Pliny the Younger clone from 1.091 to 1.010 or below. In one case, I got it down to 1.008. But, I have found that I needed to add the bulk of the sugar near the end of fermentation rather than in the boil.

seanppp said:

34 gallon batch.

84% Pale
7.5% cane sugar
6% Carapils
2.5% Crystal 40

Mashed at 150F.
Servomyces in boil.
Safale US-05. Rehydrated yeast before pitch.

1.075 OG. Pitched at 18C (64.4F).
2 days after pitch: Set to 19C (66.2C). [didn't take a gravity]
3 days after pitch: 1.040.
4 days after pitch: 1.030, set to 20C (68F).
5 days after pitch: 1.022.
6 days after pitch: 1.020, set to 22C (71.6F).

Thanks!

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I'd expect to get to at least 1.015 with that, and you still might.

Check your thermometer in some boiling water.

Thanks for the great advice everybody. You are right, I should calibrate my therometer.

Guess what? I jumped the gun a bit. Since the beer was at 1.020 for two days in a row (6 & 7 days after pitching) I *thought* it finished attenuating so I turned the chilling system up to 71.6F hoping it would clean up the fermentation byproducts, and then I posted my underattenuation question. Well, I just checked it today (9 days after pitching) and it was at 1.014! So even though it "stalled" for two days, the push in temperature really helped it! So I'll check it tomorrow and see where it is. Very interesting...