Commercial Brewing vs Homebrewing Conditioning Time

[StMarcos]

Well, I'm not a pro brewer, but I want to know IF fermenting a lager under pressure will reduce esters enough to be able to ferment above 55F... also want to know WHY! I guess that's one of the perks of homebrewing... get to tinker with the theory.

 

[Jaybird]

It's just amazing the amount of talent that is pooled together in this forum!

Great information gentlemen!

What kind of pressures are you talking about using with the spundig during primary? Just as a safety measure would you use 2? 1 for a back up? Are you filtering with Co2 in suspension? I have just never had any luck with that.

Cheers
Jay

 

[emjay]

Not sure if you misunderstood the role of pressure, or if it was misrepresented to you. The head pressure effect on ester formation, while notable isn't the primary factor as such. Essentially, what occurs is that the geometry of the tank (here is where the main influence of the head pressure comes in) drives yeast down to the center, this yeast is fermenting heavily and creating a mass of CO2 which moves upwards, carrying yeast along with it. The glycol bands on the tank amplify this effect by creating convective currents. This process actually keeps more yeast in suspension during active fermentation, this in turn both reduces some ester formation AND speeds the cleanup towards the end of active ferment. If pressure alone were the main factor, massive dish bottom tanks or horizontal tanks would give the same effect, they do not.

At first you seem to concede that head pressure itself is able to affect ester formation, but then you go on to minimize its role pretty much to the point of negligible, which I feel is misleading.

The truth is that both head pressure AND vessel geometry can influence esters, not just as variables that are inevitably intertwined, but also in an independent manner as well. While a brewer will undoubtedly get a greater effect by manipulating both variables, you can indeed suppress ester formation by increasing the head pressure even without optimizing the vessel geometry.

I've experimented on dozens of beers since I first heard Jamil Z's recommendation to ferment a saison in a carboy loosely covered in tinfoil, to make the pressure at the surface of the beer equal to atmospheric pressure (thus maximizing ester production). I've conducted double-blind tests with tasters ranging from expert palates to beer newbs. And the results have been pretty unequivocal, whether comparing the foil to a 3-piece airlock, an airlock to a blow-off tube in a jug of StarSan, or even just a blow-off to an even deeper blow-off. So now it's just another variable I'm able to take advantage of.

At some point I'd love to try fermenting my saison under vacuum!

Well, I'm not a pro brewer, but I want to know IF fermenting a lager under pressure will reduce esters enough to be able to ferment above 55F... also want to know WHY! I guess that's one of the perks of homebrewing... get to tinker with the theory.

The question is too general... it depends not just on the pressure, but on the fermentor itself, the particular yeast strain being used, and even the wort composition. Not to mention that nobody here can possibly know what degree of ester suppression YOU personally consider to be adequate. The only thing you can do is experiment with your desired recipe(s) on your own equipment.

 

[wailingguitar]

That's true, pressure does have an effect never denied it, but the geometry of the vessel is a greater factor. Note my example of large horizontal vessels, also if you look at the post on probrewer the post's author specifies that as the REASON A/B prefer horizontal ferms. Being a brewer at a mega-brewery (Miller) I think it's safe to say that his information there is correct.

Does pressure have an effect on ester production? YES. Is it the main reason that commercial breweries can flip clean beers quickly? NO. If you were to compare two beers fermented in identical unitanks, one with an open vent (minimal head pressure) and one spundig, you would find the difference between them very, very small.

 

[pjj2ba]

Exactly... Which is the basis for the old saying:

"Those who can't... Teach!"

You know, I HATE this statement. A) It suggests that teaching is not important, and is inferior to "doing" and B), that teaching is always a second choice.

What is often forgotten, is the more truthful corollary that "Those who can do.... can't teach!" Just because someone is a whiz scientist or whatever, that has no bearing on whether or not they are a good teacher. It is two different skill sets. As Piratwolf said, when the two are combined in one, it is quite glorious. Unfortunately it is not a common occurrence.

As to the benefits of knowing the science, the big plus is if something goes wrong, you have the knowledge to analyze the problem and apply a proper solution - as opposed to trial and error hoping for a fix.

I see this in the modern science lab far to often. There are lots of kits available for all kinds of procedures. You just open the kit and follow the instruction with your sample and presto, results. The kits are GREAT time savers and actually do work most of the time. However, if it fails, and if you do not understand what is going on (what the steps actually do), then typically the recourse is simply to try it again and hope it works. Now if you actually understand what processes are going on, then you could say perhaps,"Oh, I bet my sample pH was too high, if I lower it, then it should work" The net result is people are being trained up who do not really have good problem solving skills - everything has been cookie cutter. Their response to a problem is to spend a lot more time and money to fix a problem as opposed to being able to properly analyze the problem and then quickly and cheaply solve it.


Back on topic.

Here is some great reading on the subject (and other areas too!). I believe the gist is that increased CO2 levels lead to a decrease in ester formation, and that the CO2 levels are affected by the fermentor design, with there being higher CO2 levels in the big cylindroconical fermentors.

Flavor-activeesters: Adding fruitiness to beer


Effects on Flavour of Innovations in Brewery Equipment and Processing: A Review

 

[ajwillys]

Man, what a great thread. I'm specifically interested in pressure fermentation, but from a different angle. I love to add subtle ingredients that add are designed for mostly aroma more than anything. Doing it pre-fermentation never works, its "just for the neighbors" as Celis says. I'd be very interested to hear what people think of pressure fermentation as a means to control CO2 scrubbing. It seems pressurizing the tank would cause the co2 to "exit" the beer in a much more controlled fashion, perhaps limiting the scrubbing effect.

As for doing pressurized fermentation, I'd personally be VERY careful. As Jaybird mentioned, I would probably do one spunding valve to control my desired pressure and another rupture disc or similar to provide a permanent (hopefully reliable) method of blowoff in the event of failure. I'd probably get one that was at least 10-15 psi less than the fermenter rating or, if possible, maybe 10 psi higher than I thought I'd ever want the spunding set at.

Mc-Master has pressure relief valves and rupture disks that are well within a homebrewer's budget. Of course, a sanke keg is usually rated to around 50-60 psi. I'd feel very comfortable with a sanke having a pressure relief valve and a 40 psi rupture disc.