Open Fermented Lagers

My 2 cents.
While hydrostatic pressure is a real thing in large vessels it's certainly not in a 5 gallon fermenter.
You want sulfur in the beer. Not only is it a fantastic antioxidant, all of the best lagers will have a faint matchstick aroma to them.

My take on it is, open ferment or not whatever floats your boat, but I highly doubt it makes a difference.

It also makes me happy you are spunding, kudos.

 

This is one we can agree on I would emphasize though the part about sulfur aroma being faint.

In Tombstone, I almost always use Augustiner's lager yeast from Imperial Organic (L17 Harvest) for my lagers and I get a huge amount of sulfur production early but when I spund towards the end of fermentation, the sulfur is pretty much gone by then, so if sulfur is off putting to you, I'd recommend giving that strain a try. As mentioned, fermenting in carboys or in buckets might as well be the same thing as open fermentation as you have such a small amount of pressure in such small vessels. If anything, if I was homebrewing lagers, I would probably be looking for ways to decrease ester production, which would likely be a higher pitching rate and lower fermentation temperature. Open fermentation theoretically would have the opposite effect (although there's already so little pressure with the lid on, I doubt it would make a difference at this size). The higher pitching rate should also help with sulfur production.

So to summarize, I think you have something that you want to fix but that you're barking up the wrong tree.

 

Hooray!

That is exactly what I do. 2.5m pitch rate and ferment at 44-45. Spund, and hold 45 until desired extract remaining. 2206 is my house yeast.

 

Do you repitch? If so, how many generations do you use? I seem to remember that you have some lab equipment. I'd be curious to hear if you end up with smaller yeast cells in subsequent generations with such a high pitch rate. I have found that high cell counts results in less time for cells to reach full maturity and then smaller cell sizes. I used to deal with that at my last brewery, but these days I don't have to worry about re-pitching since we're always changing up the beers we brew.

 

I do repitch and I do have lab equipment!
I pitch in trub free wort, and recover my yeast with extract left (I recover at spund). Even under the scope I have zero trub. Anyways, when I put my yeast away @40F they continue to eat in storage. My harvest gets halved on recovery, then 1/2 of the harvest is direct pitched. With this system I generate 50% new cells per pitch, so essentially 100% new growth every 2 times. I have used this same method in the past to go years on the same starting 5 yeast packs. ~200 batches or so. The yeast mutated, or I like to say acclimated, so well. It would ferment like crazy down low, floc super well, and have just the right touch of sulfur. I ditched it when I built my new brewery as it sat for ~6 months. But I have just started over with the same process, with good success. The yeast have about 15 batches on them, and are starting to come around again. I cell count and scope before each batch and have very healthy cells and great viability.

 

I hope to be spunding my next lager. Is there any advantage to keeping a certain amount of pressure (say 15 psi) throughout the entire fermentation process as opposed to waiting until the gravity is within about 4-6 points of final gravity?

 

Yea, don't. Never ferment under pressure unless you have to.

 

What’s your direct pitch quantity in mls or oz if you don’t mind me asking?

 

It varies on how much knockout volume you have and your viability. So its ever changing.

For me that is usually around 500ml of pure yeast.

 

Theoretically if you spund throughout all of fermentation at 3-4 PSI, you would be emulating the type of pressure found in small-medium commercial breweries, which would decrease the ester production. You would have an increased risk of diacetyl and sulfur. The diacetyl issue should be overcome with a few extra days, the sulfur might be a problem though. I have fermented under pressure in the past with no issues in an attempt to reduce the ester production in conjunction with a higher temperature fermentation and those beers needed less lagering time. That is a common technique for large breweries. I would be prepared for disappointment unless you're willing to put in the effort of a few batches to get the process nailed.

 

I wonder how much pressure is already available through a fermentation lock? Perhaps using a small diameter blow-off tube in a full pail of water might increase the pressure and give similar results?

 

Virtually none... You need 3 feet of hydrostatic pressure to equal 1 psi.

 

I'm curious - why have you specifically chosen 2206, as opposed to others such as 2124 or WLP830?

 

Literally because it’s sulfury, and it also flocks better than those you listed.

 

Thanks - I haven't tried that one yet, but will try it the next time I need to purchase yeast.