How long until you know the yeast are gone?

[traxton]

Hey everyone! I am filtering (1 micron) a grapefruit wheat into a keg with a can of grapefruit concentrate to back sweeten it a bit. I plan to force carb and bottle. Last thing I want is bottle bombs, so how long do you think is adequate time to let it sit in the keg at cool room temp before I can be pretty sure nothing is going to ferment? Was thinking I would let the temperature settle in the cool, consistent corner of the basement, then relieve any pressure due to temperature change. Then what do you think, a week and check for pressure build up? Maybe only need to wait a couple of days?

-Trax

 

[ncbrewer]

I don't think it well sweeten back at all. I would expect the yeast to ferment the grapefruit concentrate, although I'm not familiar with how the grapefruit concentrate acts. I know wine often doesn't ferment out completely, and leaves a little sweetness. I guess I'd check gravity once in a while, and when gravity is stable it should be finished. But since it's a safety issue, I would want to hear from somebody who has done something similar.

 

[traxton]

My hope is that the 1 micron filter will hold the yeast back and I'll have a "sterile" beer coming out the other side. I'm just too weary of bottle bombs to not do something as a check to make sure nothing got through or otherwise was introduced into the "sterile" side. Figure the keg will pressurize if any fermentation starts back up. Just not sure how long to wait before I bottle.

-Trax

 

[The_Bishop]

1 micron will not filter out all the yeast, and it will re-ferment when additional sugars are added.

 

[traxton]

Good to know. Gotta get down to .5 micron, or is it just never 100%?

-Trax

 

[The_Bishop]

I'm fairly sure that .5 micron is considered 'sterile'.

However, that's a .5 micron absolute filter, so it depends on what filter setup you're using.

 

[traxton]

Just a canister filter. I'll have to look into other options. I have the kegged beer in the fridge heading to .5 Celsius. No gas on that right now. I pulled a small amount out that I have at room temp with an air lock. Going to monitor for activity over the next couple of days to see if it gets going again.

If it does, as you suggest, reestablish fermentation I'll have to consider other options. Maybe Campden tabs? Really don't want to pasteurize. If I can suppress the activity by keeping it cool, maybe I just bottle what I can keep cool and expect to use in a couple of weeks.

-Trax

 

[BrewSRQ]

I suppose you could do like winemakers do and add campden and k sorbate. Maybe look at the recommendation for wine. Then dont worry about the filter and carb in the keg.

 

[william_shakes_beer]

If you're experiencing bottle bombs, either you are bottling before fermentation is complete (wait until SG is the same for 3 consecutive days) or you're picking up a bacteria (which will work slowly and will ferment sugars that yeast can't ferment). I don't think trying to filter out the natural yeast is going to solve bottle bombs.

 

[ncbrewer]

If I can suppress the activity by keeping it cool, maybe I just bottle what I can keep cool and expect to use in a couple of weeks.

I don't know what the text books say about stopping fermentation by cooling the beer, but my wife sweetened some wine back and then kept it in the fridge. It started fermenting in the fridge (40F). Different yeast, but I still wouldn't count on the fridge to prevent bottle bombs.

 

[traxton]

Yeah, it looks like I'm either going with chemical inhibitor or just adding the juice to the glass before pouring the beer. I am, however, letting a small amount of sweetened beer sit out to see if it acts back up. Just for experiment's sake. Doing the same in the fridge to gauge just how quickly it fires back up at low temp. It's Nottingham if it's of any indication. I'll report back if anything interesting is discovered.

-Trax