Over attenuation: why and is it a problem?

That's not really over attenuated, for an IPA that's fine, the sugar will be 100% fermentable making your FG lower, you're expected final gravity doesn't make sense, with the sugar you will always have a lower FG, not higher. BJCP claims 1.010 is recommended final gravity, but you really can't tell the difference between 1.009 and 1.010 anyway. You also mashed @150 which will make a dry beer anyway. You're fine, your sugar addition made your beer more drinkable for an IPA, well done.

 

What was the OG of your IPA?

Cheers!

 

Sugar is 100% fermentable so your expected FG should have stayed around 1.015. Remember though, that is your expected range, there can be many factors that cause higher attenuation.

What was the grain bill and how much DME?

 

Also you can take variables into play like was your thermometer calibrated properly, you could have mashed lower, say 148 but had an actual reading of 150, or your hydrometer reading wasn't accurate without calculating for temperature of the finished beer...

over attenuation occurs when your beer gets waaaaay to dry for style, like 1.002 (unless it's a saison or sour, then you're pretty much good).

 

Interesting. Since it's 100% fermentable, sugar can't cause the FG to go up, by definition. I've never used the hopville calculator, so I won't comment on its accuracy. But this is a biggie, IMO. Perhaps this error should be communicated to them.

 

An OG = 1.068 and FG = 1.009 yields an Apparent Attenuation of 87% so you did indeed experience a lot of attenuation with this batch. I typically achieve 82-84% Apparent Attenuation for my IPAs (using US-05 yeast).

In my opinion you achieved a fermentable wort via your mash of low 150s (maybe you mashed at 152F). The addition of sugar (which is 100% fermentable) created an overall very fermentable wort.

You asked: "Is it just a dryer beer than expected?" In a nutshell that is the consequences of achieving high attenuation (a low final gravity). If you would prefer an IPA with less attenuation (higher final gravity) for a subsequent batch, then mashing at a higher temperature (e.g., 158F) and nixing the sugar addition will result in a less fermentable wort which will result in a higher final gravity.

I personally like my IPAs which are attenuated in the lower 80's with a final gravity of around 1.010 - 1.012.

Cheers!

 

Vikeman has a big issue with this, IIRC this is the first thing he checks when checking out a recipe calculator (I follow his brewcypher spreadsheet thread). He has pointed this issue out about hopville before.

 

A lot of the online calculators assume 75% attenuation (or whatever you have the yeast's attenuation at) no matter what the sugar source, so that's why it went up. I'm confused as to how you used the hopville calculator, though, since it has been offline for more than 6 months.

As others have stated, there are a lot of other factors; yeast pitching rate and health, oxygenation, and overall fermentability (determined by grist selection and mashing time and temp) of the wort all playing a factor. The big question is: are you happy with the beer as is?

 

Annoying, innit? Try this spreadsgeet and see if the answer changes...
BrewCipher

 

Yup. I haven't seen a commercial product that accurately predicts FG. I just change the attenuation of my yeast until it matches what I expect...

For the record, adding sugar should actually depress your expected FG (but only very minutely) as alcohol is less dense than water

 

Indeed. My sheet also takes that into account. It can actually make a pretty significant difference, about a couple of FG points per pound in a 5 gallon batch.

 

Being able to predict FG/apparent attenuation is a result of experience. I don't know how homebrewers who brew a different style using different yeasts and ingredients all the time can expect to acheive the balance they are looking for....

 

Well, they could use a spreadsheet that predicts attenuation based on yeast strain, mash time, mash length, and grist.