How does overattenuating happen.

So i have a beer i brewed, it was an American IPA. Now this beer attenuated to 83% and doesn't taste very good; my questions are: how does overattenuation happen, and what effect does it have on a beer?? Thank you in advance for the advise.

Was that a mash (or partial mash)? Number one reason I can think of for unexpectedly high attenuation is too-low mash temperature.

Did you add a lot of adjunct sugar(s)? Those are basically 90%+ fermentable.

What kind of yeast? Some yeasts attenuate more than others. And pitch rate?

Fermentation temp?

P.S., 83% AA on an IPA doesn't sound all that over-done to me, what were your gravities? How soon after bottling/kegging are you tasting? What is the not-good taste you're getting?

I used extract. No adjuncts, i used Whites labs American Ale yeast and i dont know the pitching rate i just shook the tube and threw it in. The fermentation temp outside the bucket ranged from 65-75 degrees; which i think is the main culprit cause my other batch didn't taste good either- very watery, light (but its a blonde ale so expected) and a little dry.. My gravities were OG 1.073 and my FG was 1.018, and it attenuated to 1.012. Im tasting it at 2 weeks and 4 weeks; at 2 weeks it tasted very sour, not as bitter as it should be, just down right funky; at 4 weeks it tasted better but definitley did not smell better, the bitterness came back but still a little watery. But we bottled it anyway and we are gonna see how it comes out.

Can you explain "My gravities were OG 1.073 and my FG was 1.018, and it attenuated to 1.012."?

-a.

I wondered the same thing. I figured 1.018 was target and 1.012 was measured?

My thoughts are that firstly, assuming a typical 5-6 gallon batch, you significantly under-pitched but that is not likely the cause of your issue.
Secondly, in my experience, that is a fairly typical FG for that yeast in a beer that size. I don't think you've over attenuated at all.
Based on your description of the taste I think the source of your problem may be infection.

Agreed, I would typically prefer my IPA's to finish dry and 1.018 sounds high to me. I too would be concerned about infection if it tastes sour. Carbonation will change your perception of mouthfeel and bitterness, I'd wait until it's done and re-eval. What was your recipe?

ajf said:

Can you explain "My gravities were OG 1.073 and my FG was 1.018, and it attenuated to 1.012."?

-a.

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my OG was 1.073 and my FG was 1.018 on the recipe but it attenuated to a measured FG of 1.012

But it attenuated 83% when it should of attenuated to 78%, doesn't that seem a little high an extra 5%. And yea thats what i though was an infection but that was at 2 weeks and at 4 weeks it tasted bad still but not as bad. So im waiting to see how it comes out.

chickypad said:

Agreed, I would typically prefer my IPA's to finish dry and 1.018 sounds high to me. I too would be concerned about infection if it tastes sour. Carbonation will change your perception of mouthfeel and bitterness, I'd wait until it's done and re-eval. What was your recipe?

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Fermentables
Amount Fermentable PPG °L Bill %
3 lb Dry Malt Extract - Extra Light 42 2.5 30.6%
3 lb Dry Malt Extract - Amber 42 10 30.6%
2 lb Corn Sugar - Dextrose 46 0.5 20.4%
8 lb Total
Steeping Grains
Amount Fermentable PPG °L Bill %
1 lb American - Pale 2-Row 37 1.8 10.2%
8 oz American - Caramel / Crystal 60L 34 60 5.1%
5 oz American - Smoked Malt 37 5 3.2%
Hops
Amount Variety Type AA Use Time IBU
1 oz Warrior Pellet 16 Boil 60 min 25.48
1 oz East Kent Goldings Pellet 5 Boil 25 min 5.54
1.5 oz Citra Pellet 11 Boil 15 min 13.04
1 oz Columbus Pellet 15 Boil 5 min 4.76
1 oz Amarillo Pellet 8.6 Dry Hop 10 days
1 oz Citra Pellet 11 Dry Hop 10 days
Show Summary View
Other Ingredients
Amount Name Type Use Time
2 tsp Irish Moss

LuNchBoX1371 said:

But it attenuated 83% when it should of attenuated to 78%, doesn't that seem a little high an extra 5%. And yea thats what i though was an infection but that was at 2 weeks and at 4 weeks it tasted bad still but not as bad. So im waiting to see how it comes out.

Click to expand...

The point is "should" is a relative term. The recipe may say 1.018 expected, but I like your numbers better for an American IPA. Very close to what the Pliny clone is supposed to be, matter of fact. I would suspect that whoever designed this recipe with 20% corn sugar wanted to drive up the attenuation and dry it out. I'd say you did well in that aspect, and wait to see what it tastes like carbed up. Next time if you decide you don't like such a dry IPA then cut down the sugar.

In this case, the 2 lb of sugar is your likely culprit.

ok never thought of the simple sugar but yea that could of been the reason; we'll see how it taste in a couple weeks.

When you say sour do you actually mean bitter? Loads of people mix this up, even profession chefs

No no not at all the sour was straight sour; but when i tasted it at 2 weeks the bitterness was like that of a blonde ale not a IPA, so thats why i thought infection at first with the sour, mixed with the weak hop bitterness, it tasted terrible. So at 4 weeks we tasted it and the bitterness has risen back to where it almost should be but had almost a budweiser which was not expected because i had used citra but not the ekg, and this was my first time dry hopping but i have used amarillo and citra before i gues it was a bad mix on my part. Next time-depending how it tastes- ill cut the sugar out and not use ekg cause mixed in with everything it didn't make a good combo for me.

Based on your recipe (assuming 5 gal batch), I'd expect this brew to start at 1.071-1.072 and attenuate to about 1.012-1.013, so to me you're right on the numbers. But I also agree (as others have said) that 20% of your grain bill being dextrose (or any base sugar) is crazy high for an IPA, and could lead to the sour ("cidery"?) flavor and watery mouthfeel you've experienced.

On the other hand, could the "sour" flavor just be "yeastiness"? 1 or 2 weeks in the bottle and it can still have that young, green, "overly yeasty" flavor.

I see it's now at 4 weeks in the bottle and getting better. Does it seem to be getting clearer? I.e., yeasty matter dropping out of suspension? I bet it will be even better at 6-8 weeks in the bottle. And your next batch, where you don't go over about 5-10% dextrose in the grain bill, will be better still!

Thanks for the advice. But yea i think it was all the sugar i put in it that made it attenuate so much because on brewers friend it said that it would attenuate 78% and all my beers that i have done on brewers friend have come out right on the dot for the most part, so im thinking it was the sugar; but next time ill definitely take out the sugar.