Causes of low attenuation

[Steve3730]

Just kegged an extract wheat beer and beer smith had it coming in at 1.049 and finishing a 1.013. My actual OG was1.046 so not far off but my FG was 1.020.

It was London 1968 yeast. I've used it before and always finished much lower than this. I made a 2L starter harvested 1L for later use and pitched 1L in this beer.

One concern I did have is I use a 19 gallon drum as a swamp cooler that I keep the fermenter in. I pitched at 65 degrees but than put the fermenter in the swamp cooler and the water was only like 48 degrees. Could this have shocked the yeast?

 

[Psylocide]

Well, I've seen a lot of extract batches that seem to peter out at 1.020ish range. The water in the swamp cooler was pretty cool... any idea what the temp of the beer in the fermenter was while it was fermenting?

Worst case though, I think if it did make the yeast go dormant, they should have waken up when it got back to a decent fermenting temp.

 

[Steve3730]

by the next day it was up to around 62 and stayed pretty consistent at 64-65. 14 days in primary 7 days in secondary. I've used this yeast with extract brews and had OGs around 1.065 brought down to 1.010

 

[perastikos]

I believe it has to do with the fermentability of the extract.

For example when brewing all grain, the temperature of the mash is responsible for producing both fermentables and unfermentables sugars. Raising the temperature will result in a higher FG reading, while mashing at low temperature will result in greater percentage of fermentable sugars.

Yeast's attenuation applies only to the the sugars that are fermentable by the yeast.

That's my opinion.

 

[sfish]

Have you raised the temp to 70 72? swirled the fermentor? try to do so without splashing

 

[Steve3730]

Have you raised the temp to 70 72? swirled the fermentor? try to do so without splashing

I didn't. I should have held off and tried something like that but i ended up kegging it. How will this affect flavor? This is a hoppy Wheat ibus around 45

 

[cyanmonkey]

That strain is super flocculant, isn't it? I'm guessing they pooped out a bit early. Either not enough or not healthy, enough.

Do you oxygenate? I typically add some nutrient and get I the 80th percentile on attenuation.

 

[cyanmonkey]

I didn't. I should have held off and tried something like that but i ended up kegging it. How will this affect flavor? This is a hoppy Wheat ibus around 45

It'll be sweet.

 

[Steve3730]

That strain is super flocculant, isn't it? I'm guessing they pooped out a bit early. Either not enough or not healthy, enough.

Do you oxygenate? I typically add some nutrient and get I the 80th percentile on attenuation.

I'm new into making starters and this did flocculant while in the starter. I decanted the beer off the starter and added a little more wort and nutrients a couple hours before pitch to try to get it going again.

 

[masonsjax]

I always raise the temp to the upper 60s / low 70s after primary slows down to help encourage the yeast to finish up the last few bites.

 

[NervousDad]

That is the problem with the swap cooler method. You're keeping it cool while it is fermenting and creating it's own heat. Once fermentation stops the temp also drops and the yeast flocculates. This is especially true with London yeast.


Try rousing the fermenter and raising the temperature to around 70 to get it to finish out.

 

[sfish]

I didn't. I should have held off and tried something like that but i ended up kegging it. How will this affect flavor? This is a hoppy Wheat ibus around 45

There should be sweetness. taste it if you like it drink and share

If too sweet bleed the pressure off let the keg warm to room temp. bleed often, several days the idea is the yeast may comsume some of the sweetness.

 

[Steve3730]

I will try it and see how it is before making a move with it. The yeast flocing in the starter and being pitched doesn't effect anything right?

Cold fermentation is sounding like the likely culprit here right?

 

[cyanmonkey]

No, the yeast in the starter would be expected.

I would still consider the yeast pitch. What was your OG and how big was your starter?

 

[Steve3730]

OG was 1.046 starter was a solid liter. I split a 2L starter. Harvested 1L for later use

 

[cyanmonkey]

You should have been fine. I'd imagine it was temperature, then as earlier stated.

 

[perastikos]

I don't believe that the temperature is the issue.
What ingredients did you use?
64-72F is the temperature that wyeastlab suggests. But that doesn't mean that the yeast won't do it's job at 63 or 73 degrees.
Maybe you were lower than expected,but this should delay the fermentation process, not stall it.

 

[cyanmonkey]

The temperature was at 64, the low end of the range, the majority of fermentation with a highly flocculant yeast. Low starting gravity with a big enough starter.

I'm curious what about the recipe might cause low attenuation? It was extract, so I suppose bad extract could be the issue.

 

[perastikos]

Fermentability of the ingredients.
Quoting John Palmer's How to brew:

Chapter 3 - Malt Extract and Beer Kits

3.5 Gravity vs. Fermentability

Different extracts have different degrees of fermentability. In general, the darker the extract, the more complex sugars it will contain and the less fermentable it will be. Amber extract will typically have a higher finishing gravity than pale extract and dark will be higher than amber. This is not always the case, though. By manipulating the mash conditions, the relative percentages of sugars that are extracted from the mash can be varied. A brewer can produce a wort that is almost entirely made up of highly fermentable sugars like maltose or he can produce one that has a higher percentage of unfermentable complex carbohydrates. Because these complex sugars are not very fermentable, the beer will have a higher finishing gravity. While most of the perception of a beer's body is due to medium length proteins, the unfermentable complex sugars will lend some of the same feel.

For example, Laaglander'sú DME from the Netherlands is a high quality extract that often has a finishing gravity as high as 1.020 from a common 1.040 OG.

Source: http://www.howtobrew.com/section1/chapter3-5.html


It's not a matter of "bad" extract.

 

[Steve3730]

I don't believe that the temperature is the issue.
What ingredients did you use?
64-72F is the temperature that wyeastlab suggests. But that doesn't mean that the yeast won't do it's job at 63 or 73 degrees.
Maybe you were lower than expected,but this should delay the fermentation process, not stall it.

Here is the recipe. LME and DME was Muntons brand. Grains stepped at 155 for 45 minutes. 60 minute boil


1 lbs Caravienne Malt (22.0 SRM) Grain
8.0 oz Cara-Pils/Dextrine (2.0 SRM) Grain
3 lbs 8.0 oz Wheat Dry Extract (8.0 SRM) Dry Extract
3 lbs 4.8 oz Wheat Liquid Extract (8.0 SRM) Extract
0.50 oz Citra [12.00 %] - Boil 30.0 min Hop 12.1 IBUs
0.50 oz Amarillo [9.20 %] - Boil 15.0 min Hop 6 6.0 IBUs
0.50 oz Amarillo [9.20 %] - Boil 10.0 min Hop 7 4.4 IBUs
1.00 oz Amarillo [9.20 %] - Boil 5.0 min Hop 8 4.8 IBUs
1.00 oz Citra [12.00 %] - Boil 5.0 min Hop 9 6.3 IBUs
1.00 oz Amarillo [9.20 %] - Steep/Whirlpool 15. Hop 10 6.0 IBUs
1.00 oz Citra [12.00 %] - Steep/Whirlpool 15.0 Hop 11 7.8 IBUs
1.0 pkg American Ale (Wyeast Labs #1056) [124.21 Yeast 12 -
2.00 oz Citra [12.00 %] - Dry Hop 4.0 Days Hop 13 0.0 IBUs
1.00 oz Amarillo [9.20 %] - Dry Hop 4.0 Days Hop 14 0.0 IBUs

 

[perastikos]

Carapils produces dextrin which is unfermentable. I believe that caravienne is similar to carapils.
The majority of sugars in these special grains is already there, waiting to be extracted. And these sugars are not fermentable. Perhaps there is a small amount of startches that hasn't converted to sugars. Even if that is true, still you would need to do a full mash, where enzymes from other grains would convert startches to fermentable sugars. The enzymes of the special grains are destroyed or very little.

All the sugars from these two types of ingredients along with the non-fermentable percentage of DME and LME caused your high FG.
Yeast just couldn't do anything with those and gave up, regardless of temperature.

Check out this post as well: https://www.homebrewtalk.com/f39/fermentability-dme-vs-lme-232045/#post2735648
I believe it's an experiment of fermenting out worts made of DME and LME (muntons included). FG was never below 1.013 and it got even up to 1.018. Add to that cara- malts and you go up to 1.020.


Here's another example:
One uses only carapils and makes a wort that has OG=1.050.
That doesn't mean that the FG will go down to the proper range calculated by the yeast's attenuation. I wouldn't be surprised if it would be around 1.040-1.045

 

[cyanmonkey]

Carapils produces dextrin which is unfermentable. I believe that caravienne is similar to carapils.

Steeping grains aren't adding hardly any sugars and affect OG minimally. I don't think that's it.

I'm guessing this is a 6 gallon batch?

 

[perastikos]

I disagree. Steeping (some grains) adds sugars to the wort, because the sugars have been inside there beforehand.
It's just that, these sugars are not fermentable
After all, they have potential SG http://beersmith.com/grain-list/

 

[cyanmonkey]

http://beersmith.com/blog/2009/03/22/steeping-grains-for-extract-beer-brewing/

 

[Steve3730]

5 gallon batch.

My last batch of beer recorded a higher gravity than perdicted because the steeping grains added sugars that fermented. Different brew than this so different grains. But perdicted OG as an extract was 1.062 recorded was 1.077 and it fermented down to 1.020 perdicted 1.019

 

[BryBrew]

I'm curious about this.

"It was London 1968 yeast. I've used it before and always finished much lower than this. I made a 2L starter harvested 1L for later use and pitched 1L in this beer."

Can you give any more details here on how your starter was prepared and split? I'm just curious how you kept 1L and saved the other. Could your other L have most of the yeast in it? What was viability of yeast used in starter, etc? Did you just suspend the yeast by shaking and then quickly split the 2 Ls?

 

[perastikos]

http://beersmith.com/blog/2009/03/22/steeping-grains-for-extract-beer-brewing/

Right on the spot!

The grains should be crushed to expose the sugars within the grain.

Steeped grains will not add many fermentables to your beer

Steeping will not add fermentables. It will add non-fermentables

 

[Steve3730]

I'm curious about this.

"It was London 1968 yeast. I've used it before and always finished much lower than this. I made a 2L starter harvested 1L for later use and pitched 1L in this beer."

Can you give any more details here on how your starter was prepared and split? I'm just curious how you kept 1L and saved the other. Could your other L have most of the yeast in it? What was viability of yeast used in starter, etc? Did you just suspend the yeast by shaking and then quickly split the 2 Ls?

I decanted the beer down to the yeast cake. I than added 2 mason jars of boiled water. Shook the flask up until it became a slurry. Poured off into a mason jar and kept the rest in the flask. Which I than restarted the yeast starter by adding more wort and returning it to the stir plate

 

[BryBrew]

Right on. Sounds like you probably got the pitch about right.

 

[Jfcrls]

Read previous post wrong... don't mind me.

 

[Steve3730]

So beer is tapped and going and i have to say it is surprisingly good. Little sweet base but at nearly 50ibus the hops balance against that well. The dryhops in the keg gives it awesome aroma.

 

[xdfxdgh]

Well, I've seen a lot of extract batches that seem to peter out at 1.020ish range. The water in the swamp cooler was pretty cool... any idea what the temp of the beer in the fermenter was while it was fermenting?

 

[Steve3730]

Well, I've seen a lot of extract batches that seem to peter out at 1.020ish range. The water in the swamp cooler was pretty cool... any idea what the temp of the beer in the fermenter was while it was fermenting?

That i do not know. Upgrading to a internal temp probe and controller is next on my list