Issues achieving FG Target

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THE EDJ
Posts: 28
Joined: |01 Jan 2015|, 19:37
Favourite Beer: IPA

Issues achieving FG Target

Post by THE EDJ »

Please check out my intro thread for details on our brewing setup: http://www.canadianhomebrewers.com/view ... =13&t=3353

We have brewed 4 batches in total and have had issues achieving our target FG each time. Initially I thought the issues were to do with a lack of yeast, as the recipe called for around 200 billion cells. As an example, our IPA recipe uses Safale S-04, which should have around 60 billion cells per 11.5 g packet at 90% viability. Doing the math, I would need at least 3 packets of dry yeast to get close to enough cells. The target FG for the recipe is 1.014. The first time we brewed the recipe we used just one pack of yeast and hit an FG of 1.023. The second time, we used three packets of yeast and hit a FG of 1.028.

Coming out of the mash tun, our pre-boil gravity target was 1.044, we hit 1.043 each time. The OG target going into the fermentor was 1.055, we hit 1.056 each time. We are able to consistently hit those targets with each recipe (obviously the targets vary depending on the recipe, but these reference the two times we brewed our IPA recipe).

We shake the fermenter for a good minute prior to pitching the yeast and we have rehydrated and proofed the yeast per the manufacturers instructions each time. We are using a two stage temperature control for fermentation. The fermentor goes into the fridge with a lamp. A thermocouple is inserted into a thermowell on the fermentor and either turns the fridge on to cool or turns the lamp on to heat. It's a simple system that maintains consistent temperature and works well. We ferment between 65 an 67*F. On the second batch of IPA we had it set to 67*F to hopefully keep the yeast a little more active. We also agitated the yeast (carefully stirred the yeast up) as it had settled after 2 days. We are getting extremely vigorous fermentation over the first two days. We get 2-3 bubbles per second out of the air lock and are seeing a gravity of 1.034 after two days, and 1.030 after four days. Fermentation is two weeks with a cold crash for another week or two afterwards.

Our beer tastes great, looks great, carbonates well, but we just can't get enough of those sugars to convert to alcohol. What should we look at in order to figure out what's wrong? Are we doing anything wrong? What could we do to achieve our FG target?

Goulaigan
Posts: 456
Joined: |14 Jan 2014|, 23:05
Favourite Beer: Mine
Location: Goulais River, ON

Re: Issues achieving FG Target

Post by Goulaigan »

I can't see anything wrong with your process, haven't used s-04 but as long as you are within the temp range for the yeast and pitch enough you should get very close to the advertised attenuation for the strain.

The only 2 things I would be looking at is your hydrometer or refractometer, try another one or try recalibrating and secondly mash temp - If your mash temps are too high could definitely cause attenuation issues. Sounds like you have a few thermometers or I would suggest trying a few different ones. Hopefully some of the brewmasters around here can chime in with some other suggestions...

THE EDJ
Posts: 28
Joined: |01 Jan 2015|, 19:37
Favourite Beer: IPA

Re: Issues achieving FG Target

Post by THE EDJ »

We do use a handheld digital thermometer as well to check temps so I believe all of our thermometers are accurate. Our mash profile targets around 150-152*F for 60 minutes and 168*F for mashout. Fly sparge at 168*F. We are able to hit these targets without much trouble.

Doc_Drive
Posts: 1039
Joined: |12 Feb 2013|, 14:55
Favourite Beer: German wheat
Location: Calgary

Re: Issues achieving FG Target

Post by Doc_Drive »

Hi EDJ,

How do you measure your FG?

Dave
Posts: 151
Joined: |23 Feb 2012|, 15:58
Favourite Beer: mine

Re: Issues achieving FG Target

Post by Dave »

Hi
Could you post the recipe?
What was your mash temp?
Do you have confidence in the accuracy of your mash thermometer?
Are you hitting mash temp right off, or do you have to adj?
Preheating tun?
Are you stirring mash well when checking temp?
Most conversion takes place in first 15 min. of mash.
Is it always 04?

Doc_Drive
Posts: 1039
Joined: |12 Feb 2013|, 14:55
Favourite Beer: German wheat
Location: Calgary

Re: Issues achieving FG Target

Post by Doc_Drive »

I saw in your equipment post that you only use a refractometer. When I enter your values in my calculator, I get:
OG 1.056
FG 1.007
ABV 6.3

OG 1.056
FG 1.008
ABV 6.2

This is with the refractometer correction and sounds very reasonable to me. Did you factor in that ethanol has a different refractive index than a sugar solution?

Cheers!

THE EDJ
Posts: 28
Joined: |01 Jan 2015|, 19:37
Favourite Beer: IPA

Re: Issues achieving FG Target

Post by THE EDJ »

Doc_Drive wrote:I saw in your equipment post that you only use a refractometer. When I enter your values in my calculator, I get:
OG 1.056
FG 1.007
ABV 6.3

OG 1.056
FG 1.008
ABV 6.2

This is with the refractometer correction and sounds very reasonable to me. Did you factor in that ethanol has a different refractive index than a sugar solution?

Cheers!
Well that's very interesting! Being a total noob, I did not consider that ethanol had a different refractive index than sugar. Makes sense, but I'm not sure how to measure this using the refractometer we have.

I found this http://seanterrill.com/2012/01/06/refra ... alculator/
Entering the Brix% values from this scale (same as my refractometer), I entered the original RI as 14.2 (1.056) and the final RI as 7.5 (1.028), which gives an FG of 1.014 (target for the recipe) and an ABV of 5.4%. So I guess we are actually doing pretty well then?

Doc_Drive
Posts: 1039
Joined: |12 Feb 2013|, 14:55
Favourite Beer: German wheat
Location: Calgary

Re: Issues achieving FG Target

Post by Doc_Drive »

You're doing awesome! Being that consistent is rare - especially when you're just starting out...

What kind of engineers are you guys? Just out of curiosity...

Doc_Drive
Posts: 1039
Joined: |12 Feb 2013|, 14:55
Favourite Beer: German wheat
Location: Calgary

Re: Issues achieving FG Target

Post by Doc_Drive »

Btw I use BrewTarget (Freeware) and it has a refractometer correction tool built in... That's what I use...

THE EDJ
Posts: 28
Joined: |01 Jan 2015|, 19:37
Favourite Beer: IPA

Re: Issues achieving FG Target

Post by THE EDJ »

This is great news! Appreciate the input and thanks for setting things straight! I was rather discouraged, but am now motivated to keep going!

Cheers! :cheers:

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