FG numbers off

[DarrellQ]

For the second time, I brewed a Pliny the Elder clone (the first one turned out great and FG was 1.006). For that brew, I used two packages of WLP-001, but because of shipping during the summer, THIS TIME I pitched two packages of US-05. OG was 1.075, I did not use a starter, it took off in about 5 hours, and was vigorous for about 6 days. I fermented at 65 degrees and bumped it 68 degrees to finish. It is 16 days post brew and I took a FG measurement with a hydrometer today before cold crashing.

First, let me say that there was so much trub in the bottom over the spigot that it is impossible to draw a clear sample. My FG is 1.015. Did the trub in the test tube affect this number? If it is indeed 1.015, I know a big effect on ABV, but what effect will it have on taste? What could have gone wrong?

Many thanks for your input!

 

[VikeMan]

Per your numbers, you got 80% Apparent Attenuation, which sounds fairly resasonable to me, from what I know of PtE. But it sounds like you expected a lot more attenuation? If so, why?

If you'd like to post your grain bill, mash temp, and mash length, I can tell you what kind of attenuation I would expect with US-05.

 

[IslandLizard]

Did the trub in the test tube affect this number?

It surely can, creating extra buoyancy. So does dissolved CO2 in the sample.

If you let the sample sit for a few hours most trub will sink. Then just decant off the clearer beer into another cup/beaker, leaving the trub behind. To degas it, stir the beer well in the beaker, then pour into your hydrometer jar.

I suck/siphon hydrometer samples out of a lidded bucket through the airlock hole, using 2' of skinny 5/16" OD tubing (after removing the airlock). No trub.

 

[DarrellQ]

Per your numbers, you got 80% Apparent Attenuation, which sounds fairly resasonable to me, from what I know of PtE. But it sounds like you expected a lot more attenuation? If so, why?

If you'd like to post your grain bill, mash temp, and mash length, I can tell you what kind of attenuation I would expect with US-05.

13 lbs 2-Row, 1 lb Carapils, and 6 oz Crystal 40L. Mashed at 151 for 90 minutes. Per IslandLizard, the trub did sink, and my FG looks to be 1.010. I only expected lower FG, because the first time I brewed it, FG was 1.006. The only difference this time was US-05 versus WPL-001.

 

[VikeMan]

My guess is you're done, but I'll run it anway. No sugar in the recipe? (And 5-gallon batch?)

ETA: Assuming no sugar.... a 1.075 OG from those grains, and a 90 minute mash at 151F, with US-05, BrewCipher would predict an FG of 1.013.

 

[DarrellQ]

My guess is you're done, but I'll run it anway. No sugar in the recipe? (And 5-gallon batch?)

ETA: Assuming no sugar.... a 1.075 OG from those grains, and a 90 minute mash at 151F, with US-05, BrewCipher would predict an FG of 1.013.

Oops, forgot, yes, 1 lb corn sugar. Thanks!

 

[VikeMan]

Oops, forgot, yes, 1 lb corn sugar. Thanks!

Ok, with one pound of corn sugar, plus those grains hitting a total OG of 1.075, plus your other details, BrewCipher predicts... 1.010.

 

[DarrellQ]

Ok, with one pound of corn sugar, plus those grains hitting a total OG of 1.075, plus your other details, BrewCipher predicts... 1.010.

Great! Exactly what I hit! Thanks!

 

[TheMadKing]

It surely can, creating extra buoyancy. So does dissolved CO2 in the sample.

If you let the sample sit for a few hours most trub will sink. Then just decant off the clearer beer into another cup/beaker, leaving the trub behind. To degas it, stir the beer well in the beaker, then pour into your hydrometer jar.

I suck/siphon hydrometer samples out of a lidded bucket through the airlock hole, using 2' of skinny 5/16" OD tubing (after removing the airlock). No trub.

https://www.homebrewtalk.com/threads/anyone-have-a-beer-degassing-hack.679839/post-8880030
I'm just going to leave this here

 

[Falstaff]

You won't be able to taste the difference to 1.006 and 1.015, if it makes you feel better.

https://brulosophy.com/2015/10/12/the-mash-high-vs-low-temperature-exbeeriment-results/
His difference was pretty much the same as yours.

 

[TheMadKing]

You won't be able to taste the difference to 1.006 and 1.015, if it makes you feel better.

https://brulosophy.com/2015/10/12/the-mash-high-vs-low-temperature-exbeeriment-results/
His difference was pretty much the same as yours.

Taking the results of a single "study" and applying them universally is not good reasoning.

Based on this data it would be accurate to say that: in a low gravity beer with a simple grist and moderate to low hop character, it is difficult to distinguish a FG difference of 0.009 between two beers that are otherwise nearly identical. More sensory analysis is needed to definitively show that this difficulty in perceiving the difference is not due to environmental factors, training of the panelists, or the specific composition of the test beer.

There are many other variables in play in Pliny since it is a much more heavily hopped beer with a very high OG. Factors such as balance and alcohol perception for example may also influence perception.

 

[cmac62]

^^ I'd say, based on this experiment and anecdotal data, mine and other's here on HBT, it is very unlikely that you will be able to taste the difference between a FG of 1.006 and 1.010 in a cold and carbonated beer.

 

[Falstaff]

^^ I'd say, based on this experiment and anecdotal data, mine and other's here on HBT, it is very unlikely that you will be able to taste the difference between a FG of 1.006 and 1.010 in a cold and carbonated beer.

Yeah I brewed a stout twice and it was about ten apart and I thought they tasted exactly the same.

Anecdotal, and maybe I don't have the best palate, but I brew for my head and anything under 1.02 tastes pretty similar to me.