how to precisely control FG

[bmbigda]

I'm about to brew a batch of beer, and it's important that I end up with a final gravity of 1.018. I brew a lot (all grain, temperature control, starters) and I just about always end up at 1.010-1.012 provided the OG is something under 1.090ish. This time, it's critical that I end up with residual sweetness, and I'm looking for advice/experiences. Some specifics:

- The grain bill is 80% vienna, with munich and pils
- The OG is going to be 1.075
- I plan to pitch 2 packs of US-05
- I have access to a refractometer
- I control ferment temps in a chest freezer with a 2-stage Love controller

A few methods come to mind...

- high mash temp (but how high? 156?)
- low ferment temp (but how low? 60?)
- take constant gravity readings and cold crash at 1.018? Seems easier said than done, consider I'd have to be home when it gets to that point, and it will happen within 48 hours of pitching.

I think in reality I can only try a combination of the above methods and hope to land near 1.018?

Thanks!
Bryan

 

[cadarnell]

mash high and use a yeast known for finishing high .. maybe ?

 

[beergolf]

The yeast will eat the fermentable sugars. Mashing high will get your FG up some. Use a yeast that does not attenuate well.

If you are planning to bottle DO NOT cold crash to stop fermentation. When you bottle the fermentation will start again and you will have bottle bombs. You cannot decide when the yeast stops, it is up to the yeast.

 

[FRS]

+1 to everything above. You could also add some dextrin malt, this would increase FG, but might not add the sweetness you desire.

If you really need a specific FG I've read that you can do the following:
1) let it ferment out as it normally would, say to 1.014
2) cold crash it hard and long to knock as many yeast out as you can
3) add Potassium Sorbate to prevent the few yeast that remain from multiplying
4) Sweeten as desired. Add enough DME/Sugar/honey/whatever to get your gravity where you want it.

You would have to force carb in this case, since the few yeast left won't be able to ferment the sugar you add.

Personally, I wouldn't go this route, but it is a possibility. I'd just let the beer finish and enjoy however it turns out.

 

[BrewerBear]

just curios what is the importance of ending at 1.018?

 

[JollyIsTheRoger]

You could just try adding Lactose to it, and just enough for .008 gravity points. So if you normally finish at 1.010 then this will eat the same amount of sugars and end up at 1.018. Think that theory makes sense.

 

[TarheelBrew13]

I'm not am exert on this but you could use Champagne yeast to kill your beer yeast. There are sugars in beer that Champagne yeast cannot eat but that beer yeast can. If you time it right and mash appropriately, you could probably get your gravity where you want it and still be able to bottle condition.

 

[Polboy]

Low mash temp and/or using low attenuation yeast is the way to go

 

[bmbigda]

just curios what is the importance of ending at 1.018?

it's a clone attempt of a beer that has a 1.018 FG and the small amout of sweetness plays a key role in the beer's flavor profile.

 

[bmbigda]

+1 to everything above. You could also add some dextrin malt, this would increase FG, but might not add the sweetness you desire.

If you really need a specific FG I've read that you can do the following:
1) let it ferment out as it normally would, say to 1.014
2) cold crash it hard and long to knock as many yeast out as you can
3) add Potassium Sorbate to prevent the few yeast that remain from multiplying
4) Sweeten as desired. Add enough DME/Sugar/honey/whatever to get your gravity where you want it.

You would have to force carb in this case, since the few yeast left won't be able to ferment the sugar you add.

Personally, I wouldn't go this route, but it is a possibility. I'd just let the beer finish and enjoy however it turns out.

faux-pasteurizing and back sweetening is a very interesting idea i hadnt though of.

this is an attempt to clone a beer for a competition we're having in our brewclub, so i think i'm going to try the high mash temp/low ferment temp/poor attenuating strain route this first time, and see how it turns out.