6 replies to this topic

[SchwanzBrewer]

I came across this by accident today while looking for natural keg carbonation techniques. There is a huge thread on Home Brew Talk about it. Basically the technique is to transfer and pitch straight to a keg and let the beer ferment under pressure. This naturally carbonates the beer. Transfers from the fermentation keg must be made to another keg that is at the same pressure via a counter pressure filler. After reading a few articles I have yet to see any true benefit to this technique. The theory behind it is that when breweries ferment in large vessels the yeast are under pressure and they are trying to mimic that. Somehow I don't think it matters. I think there are enough variables to track and control already and the fact that these guys are making good beer is regardless of the technique. I would like to see if there was a difference in taste between a CSPF beer, a naturally carbed beer via krausening, a normal natural carbonation via sugar addition, and one that is force carbonated. Anyone want to try? Anyone ever done this? Cheers,Rich

[chuck_d]

As a point of language, I like to call bunging and using the end of carbonation "natural" carbonation. What you call "normal natural" I like to call priming. So I break it down like this... Natural - use of the final degree or so of fermentation to carbonate. I've seen it done by fermenting in pressure-rated vessels and bunging them, rather than transferring, but I'd count them the same kind of carbonation technique Krausening - adding actively fermenting wort to carbonate Speise - adding wort, generally stored wort from the same kettle batch as the fermented beer Priming - adding non-wort fermentable sugar, like dextrose or maple syrup Forced - using an external source of CO2, can be captured CO2 from fermentation, methods include inline injection, in-tank injection, etc. Yeah, I think that's it. I break it down this way due to math, probably among other logic I'm not thinking of at this hour. I'll check out that wiki in more depth, but I wanted to point out that pressure definitely impacts yeast flavor production, and is something you have to think about if you plan to replicate a recipe from one brewery to another, especially if fermentation operations are significantly different (say flat rectangular open fermentors in a brewery you just acquired in another country but want to make your beer that you've developed at home in a CCT).

[Kellermeister]

I don't want to have to clean out a cornie after a full fermentation in the cornie. I am interested in what Chuck D calls a speise, adding wort to a keg with fully fermented beer to pressurize it. Or priming with sugar. I would also be interested in using one cornie to ferment in to create co2 pressure to fill or pressurize a number of other cornies with beer in them. I think there are pressure release valves that you can get that would limit pressure and blow off any pressure above a certain level, say 20lbs. I wouldn't want any foam to blow into the other kegs though, so the fermenting cornie should only be half full or less, and maybe there needs to be an empty cornie to catch any blowoff before connecting to other cornies with beer. But as far as a normal fermentation, I prefer to do that at ambient pressure in a carboy with a blowoff hose.

[SchwanzBrewer]

As a point of language, I like to call bunging and using the end of carbonation "natural" carbonation. What you call "normal natural" I like to call priming. So I break it down like this... Natural - use of the final degree or so of fermentation to carbonate. I've seen it done by fermenting in pressure-rated vessels and bunging them, rather than transferring, but I'd count them the same kind of carbonation technique Krausening - adding actively fermenting wort to carbonate Speise - adding wort, generally stored wort from the same kettle batch as the fermented beer Priming - adding non-wort fermentable sugar, like dextrose or maple syrup Forced - using an external source of CO2, can be captured CO2 from fermentation, methods include inline injection, in-tank injection, etc. Yeah, I think that's it. I break it down this way due to math, probably among other logic I'm not thinking of at this hour. I'll check out that wiki in more depth, but I wanted to point out that pressure definitely impacts yeast flavor production, and is something you have to think about if you plan to replicate a recipe from one brewery to another, especially if fermentation operations are significantly different (say flat rectangular open fermentors in a brewery you just acquired in another country but want to make your beer that you've developed at home in a CCT).

Thanks chuck! I was a little distracted last night and at a loss for descriptive words. I think that pretty much everyone ferments under some pressure. There has to be positive pressure in the carboy or bucket in order to push CO2 out, probably 1psi or less, but some pressure. But the guy in the article is talking about fermenting at 30 - 60 psi. I agree that the yeast most likely reacts differently. Its kind of like SCUBA diving, as you go deeper and the pressure increases, Nitrogen becomes more soluble in your blood. My guess is that yeast probably take in gasses too and behave differently at pressure. I'll have to dig up my "Yeast" book and see what it has to say. Cheers,Rich

[davelew]

Thanks chuck! I was a little distracted last night and at a loss for descriptive words. I think that pretty much everyone ferments under some pressure. There has to be positive pressure in the carboy or bucket in order to push CO2 out, probably 1psi or less, but some pressure. But the guy in the article is talking about fermenting at 30 - 60 psi. I agree that the yeast most likely reacts differently. Its kind of like SCUBA diving, as you go deeper and the pressure increases, Nitrogen becomes more soluble in your blood. My guess is that yeast probably take in gasses too and behave differently at pressure. I'll have to dig up my "Yeast" book and see what it has to say. Cheers,Rich

I don't think the nitrogen would affect the yeast nearly as much as the change in pH from the extra CO2 in solution due to higher pressures. It's hard to list the number of yeast biochemical pathways affected by pH-- it's pretty much all of them.

[SchwanzBrewer]

I don't think the nitrogen would affect the yeast nearly as much as the change in pH from the extra CO2 in solution due to higher pressures. It's hard to list the number of yeast biochemical pathways affected by pH-- it's pretty much all of them.

I was just using nitrogen solubility in blood as an example. Who knows what happens to the yeasties.

[chuck_d]

30-60 PSI doesn't sound correct, sounds way high close to the point where OldFart would see his yeast stop fermenting. He got backpressure due to CO2 collection (make you own CO2 thread). Looking in my notes, these are some of the effects of increased CO2 backpressure: decreased fusel alcohols, decreased esters, increased acetaldehyde, oh wait, I actually wrote a specific question on the Siebel Study Guide for this... 23. How does increased pressure impact yeast flavor production?

a. Increased dissolved CO2, acetaldehyde, diacetyl

b. Decreased esters and fusel alcohols

In another section... 18. How much backpressure is commonly used in fermenters?

a. 5 or higher PSI of backpressure is where you can influence ester production. Most people set the blowoff at 0.3 to 0.5 PSI.

I still haven't read the link yet, sorry, I'll get to that at some point I suppose