Over attenuation

[briggssteel]

So I just got done bottling my Kölsch and it's way over attenuated. My OG was 1.048 (which is what I wanted) and my final gravity was 1.002, which is obviously extremely low. I'm thinking it has to be infected because I don't know how else it could finish so low, but trying it at bottling I didn't get any funky/sour flavors.

Some other info that would probably help:

It's a 5 gallon batch

My hydrometer reads at 1.000 with water so I believe it's accurate.

I used White Labs Kölsch yeast.

I made a 1500ml starter with 2 vials, which upon checking later with a yeast pitching rate calculator is too big of a starter.

I mashes in at 149 and I have a lab calculator so I believe that's accurate.

I fermented at 59 for 3 weeks and lagered for a month at 38.


Come to think of it, my last 4 batches have finished below 1.010 so this a reoccurring issue with my beers. They always are pretty good (and of course dry), but at 1.002 I'm thinking I have to be doing something wrong.

 

[Pie_Man]

I think it is a good practice to always bottle condition your beers inside some form of container that can contain glass in the event of an exploding bottle and also contain the beer for easy clean up. A plastic storage bin or a box lined with a garbage bag are good choices.

It is posssible that you just over pitched your yeast, I cannot tell based on your OP, but a 1.5L starter with two vials could be a lot of yeast depending on your yeast's manufactur date. According to yeastcalculator.com, a 5 gallon hybrid fermentation requires 225 billion cells for a 1.048 OG wort. Do you know how many estimated cells you pitched? If your beer tastes fine after a few weeks and months, you likely just overpitched. If it gets funky, there's something else going on.

 

[Reef]

Mashing at a lower temp will allow beta amylase enough time to break down your wort into smaller fermentable chains for your yeast.

You achieved an attenuation of around 78% which is higher than the expected 69% for that strain, but not to far out of norm, especially with the lower mash temp. If you want a more full-bodied beer in the future, try upping your mash temp to around 154. That will allow alpha amylase to break your fermentables into larger protein chains.

 

[Undead8]

Over pitching would not convert unfermentable sugars to fermentable sugars.

What is your recipe? Do you have any unfermentable malts such as crystal/cara?

Did you mash longer than usual at 149 F or lower?

Did you adjust your hydrometer reading for the temperature?

 

[Qhrumphf]

1.048 to 1.002 is not 78% attenuation. It's more like 95% attenuation. Only time I get attenuation like that is a high-attenuating Belgian strain and/or bugs, or at least a lot of sugar in the recipe, usually both. Even mashing that low, that reading is strange. If that's truly and accurate reading, then I'd be worried too.

I routinely had issues with overattenuation until I switched to a Thermapen. My old thermometer, while accurate at 212 and 32, was reading very high in mash range. I was mashing 5 degrees (or more) below what I thought I was. I'd be wary of an infection, but you may have just been mashing very, very low.

 

[WoodlandBrew]

Things may look a little out of perspective because we are looking at apparent attenuation.

1.048 to 1.002 is not that much drier than 1.048 to 1.010. An apparent attenuation of 96% vs 79% is a true attenuation of 78% vs 64%.
Going from 1.048 to 0.989 would be full attenuation of the sugars.

http://pint.com.au/calculators/alcohol/

To increase the final gravity mash temperature can be increased, or mash time can be reduced. Also, if there is not currently a mash out in your schedule you may consider adding one.

http://www.woodlandbrew.com/2013/01/measured-mash-temperature-effects.html

 

[briggssteel]

Over pitching would not convert unfermentable sugars to fermentable sugars.

What is your recipe? Do you have any unfermentable malts such as crystal/cara?

Did you mash longer than usual at 149 F or lower?

Did you adjust your hydrometer reading for the temperature?

My recipe is:

6 gallon batch

9lbs Pilsner malt
.5lbs light Munich
.5lbs American wheat

Mash for 60 minutes at 149 with a ratio of 1.33 quarts per pound

I boiled for 90 minutes, cooled and took 5 gallons to the fermenter


As for my hydrometer reading, the OG reading I took in the low 70's and my FG I assume was in the low to mid 60's if I were to guess. That's what the stick on thermometer was reading on the carboy when I was bottling.

My main concern is to make sure my beer isn't infected and causing it to drop the final gravity that low. If it isn't I'll just start adding some catapults and mashing higher. I'm going to be extra thorough with cleaning and sanitation regardless on my next batch. I didn't detect any funky wild yeast flavors or any obvious sourness but I don't have an expert palette. I did get a little hint of a dry, white wine character, but I know that's also an ester that can come with this strain of yeast. I'm considering submitting it for competition to see if any judges pick up on any bugs that I'm not.

 

[Undead8]

I had an infection once a long time ago because of extremely bad sanitation (let's call that an experiment).

It tasted like vomit. And I don't have an expert palette!

If it was infected, I think you would know right away by tasting it. It's probably just a very dry beer!

 

[MaynardX]

I don't think this is over attenuated for a Kolsch at all. I strive to get attenuation like this in styles such as Kolsch, Pilsners and Saisons. A low mash temp like 149 will give you a well attenuated beer. I usually mash my Kolsch at 145.

 

[Pie_Man]

I don't think this is over attenuated for a Kolsch at all. I strive to get attenuation like this in styles such as Kolsch, Pilsners and Saisons. A low mash temp like 149 will give you a well attenuated beer. I usually mash my Kolsch at 145.

~96% apparent attenuation is very high. White Labs lists the apparent attenuation for this strain at 72-78%.

With aa that high, I suspect a combination of issues is likely the culprit. Probably over pitching, very low mash temp, and equipment calibration (hydrometer and/or thermometer), assuming the beer tastes fine.