Open Fermentation with Positive Pressure

[Skystrider17]

I had an idea this morning after reminiscing about a friend's bachelor party in Asheville and a trip to Wicked Weed Brewing. They had a saison fermenting in an open container within a room that had positive pressure, and a mirror angled on top of the vessel for viewers; quite impressive.

I read up on the benefits of open fermentation and the largest is greater ester development, and healthier yeast for reharvest. Typically though only several hardy yeast strains (ex. yorkshire ale) are used, as others can be infected easier. My idea is that the use of positive pressure, along with clean filtered air, will keep the bugs out, and allow experimentation with open fermentation and alternative yeasts.

I purchased an 18 gallon rubbermaid tote and some PVC. I plan on wrapping the frame in plastic and using a computer fan and .3 micron HEPA filters to create the pressure. The picture is the same so far, need to get some more pvc.

I'd appreciate any insights or thoughts from those who've done anything like this before (open fermentation, etc.

 

[Skystrider17]

So my Open Fermentation Positive Pressure (OFPP) sat unused for a while, but I finally decided to give it a go. I brewed the Moose drool (slobber?) recipe found here on HBT, a 10 gallon batch and pitched two vials of British Ale into it.

Set it up in my basement where it's generally cooler, 67ish, and turned on the fan.

Pretty crazy krausen as you can see; I left it down to primary for about 2 weeks with the fan blowing the whole time.

Just recently secondaried it and took a taste - nothing like any beer I've ever made before, very funky and almost tasted like a sour. I know it isn't infected because there were no signs, kept in a sterile environment the whole time. I'm pretty excited for how this will turn out, in addition to experimenting with more yeast strains.

 

[mkyl428]

Nice! looking good, keep us posted!

 

[Gavin C]

That's one heck of a cool idea.

Not seeing your "sterile" environment though. If it's tasting sour that would be entirely consistent with an infection.

2 weeks open and a fan blowing on it your chances of keeping nasties out are slim IMO.

Maybe a shorter open ferment prior to closing the lid once krausen is dropping could be considered.

Not trying to rain on your parade though. Never seen this before. Really cool. Nice job.

 

[jddevinn]

Instead of using a fan, filters and possible infection.. couldn't you just drape the sanitized plastic over the open fermenter and get the positive pressure build of from CO2 being released?

 

[Skystrider17]

The plastic wrap is not completely airtight; getting an airtight seal would require some re-engineering, and duct tape is not forgiving with the plastic. Also I thought that would kinda defeat the purpose since carboys already produce a hypoxic environment.

Currently letting the beer sit with some fining agents before I keg this weekend. I wouldn't be surprised if something wild did get in there; although I'm sure my filter was effective I'm not sure by how much, wouldn't be surprised if something got through it. I'll follow up with tasting notes once the beer is kegged and carbed.

 

[Skystrider17]

Here is a picture of my inspiration from Wicked Weed in Asheville, NC. They allow the saison to open ferment, with an angled mirror over the vessel for viewers to see. The fermenter is kept in a sealed room with positive pressure.

 

[Bellybuster]

I don't see a fermenter in a sealed room with positive pressure as open fermenting at all.

 

[Skystrider17]

OK so update

Leaving the beer in the fermenter for 2 weeks I have basically made malt vinegar.

I'm going to try using this again but only for a few days before racking off to a secondary; basically as soon as primary fermentation is done.

 

[Gavin C]

thanks for the update. Very forthright of you to update with less than desirable results. I'm sorry this didn't work out but I applaud your ingenuity.

I'd try again minus the fan and pop the lid on once krausen drops. Rack to keg/bottle once FG is reached