Does pressure stop fermentation?

[Lycoperdon]

I was talking to guy who sells kombucha here in Oakland about how he bottles it. He just uses glass bottles with plastic lids. There is a rather complicated process used to bottle beer (I'm told it's so the bottles don't explode) But he says that pressure stops the fermentation and that you don't have to worry about it with kombucha.

Is this guy right? Is the same true about beer? Has anyone ever even had a bottle explode? (I never have...)

I searched the internet for answers and I found this article (below) but it is kinda confusing and I'm not sure how much pressure is in a bottle of beer~

Titre du document / Document title
How does yeast respond to pressure?
Auteur(s) / Author(s)
FERNANDES P. M. B. ;
Résumé / Abstract
The brewing and baking yeast Saccharomyces cerevisiae has been used as a model for stress response studies of eukaryotic cells. In this review we focus on the effect of high hydrostatic pressure (HHP) on S. cerevisiae. HHP exerts a broad effect on yeast cells characteristic of common stresses, mainly associated with protein alteration and lipid bilayer phase transition. Like most stresses, pressure induces cell cycle arrest. Below 50 MPa (500 atm) yeast cell morphology is unaffected whereas above 220 MPa wild-type cells are killed. S. cerevisiae cells can acquire barotolerance if they are pretreated with a sublethal stress due to temperature, ethanol, hydrogen peroxide, or pressure. Nevertheless, pressure only leads to protection against severe stress if, after pressure pretreatment, the cells are also re-incubated at room pressure. We attribute this effect to the inhibition of the protein synthesis apparatus under HHP. The global genome expression analysis of S. cerevisiae cells submitted to HHP revealed a stress response profile. The majority of the up-regulated genes are involved in stress defense and carbohydrate metabolism while most repressed genes belong to the cell cycle progression and protein synthesis categories. However, the signaling pathway involved in the pressure response is still to be elucidated. Nitric oxide, a signaling molecule involved in the regulation of a large number of cellular functions, confers baroprotection. Furthermore, S. cerevisiae cells in the early exponential phase submitted to 50-MPa pressure show induction of the expression level of the nitric oxide synthase inducible isoform. As pressure becomes an important biotechnological tool, studies concerning this kind of stress in microorganisms are imperative.
Revue / Journal Title
Brazilian journal of medical and biological research ISSN 0100-879X CODEN BJMRDK
Source / Source
2005, vol. 38, no8, pp. 1239-1245 [7 page(s) (article)]
Langue / Language
Anglais
Editeur / Publisher
Associação Brasileira de Divulgação Científica, Ribeirão Preto, BRESIL (1981) (Revue)
Localisation / Location
INIST-CNRS, Cote INIST : 14110, 35400013239836.0120

[Tim Hall]

Sorry I didn't quite follow the full technical stuff you posted, but here's what I know:

Pressure, induced both by carbonation and sheer volume/weight of ferment, definitely affects fermentation. I don't know how much pressure you would have to apply to the yeast before they stop fermenting altogether, but I suspect it would have to be pretty high. I've never heard of anyone's beer fermentation stopping because of pressure.

Believe it or not the shape of the fermentation vessel actually affects the character of the beer. Apparently yeasts express more esters under higher pressure. So a tall, slender fermentation tank produces a more aromatic ferment than a wide, low tank using the same yeast. Of course with a typical 5-gallon volume of homebrew, this doesn't really apply.

[Tim Hall]

Lycoperdon, I should have added that I HAVE seen beer bottles explode from over-carbonation (my brewing associate had this happen to several bottles), and I have personally had ginger beer build up enough pressure to blow bail-top lids right off...not blown open, but rather blown off - lid, heavy-gauge wire keeper and all.

[Tom]

Tim,
so when would you know that the ginger beer is ready? Is it similar to fermenting kombucha without the mother? You let it sit for a while in a large container and then transfer it to the smaller bottle.

But when do you know it's ready for drinking if you can't taste it like you do with kombucha because you bottle it?

Thanks

[Tim Hall]

Well, in my experience with ginger beer you're usually not letting it ferment quite to the point that it really tastes like a "fermented" beverage the way kombucha might. It's more just to develop carbonation. You could, of course let it play out longer, but I would suggest treating it more like kombucha by fermenting in an unpressurized container first as you suggest. A friend of mine let a ginger beer play out til it was dry, but this is really a "beer-beer" rather than a "small beer" because it was definitely alcoholic.

So how do you know it's ready? Hard to say exactly. Basically I designate one bottle to open periodically and test the pressure level. I can't recall exactly, but it seems Sandor's book suggest a fermentation time of a few days to a week or so. BUT I've had ginger beer build up enough carbonation within just 48 hours to come pouring out like shook-up champagne.

Beer (barley beer that is) is a different matter. Typically you allow the ferment to play out fully (or crash the ferment with very low temperatures) then you add just the right amount of sugar to your bottled beer to produce the appropriate level of carbonation. Or you force carbonate it with canned CO2 (not my favorite approach).

Because you'll always have a good amount of residual sugar left in ginger beer, you can't really use this method.

[Lycoperdon]

I posted this on a home brew forum and here are the responses I got.

At those pressures cited in that write up the bottle would not stand a chance and the beer would be grossly overcarbed. 50Mpa (500atm) is 7200psi. Its not the pressure that stops yeast its the lack of fermentables . If there is to much fermentables the beer will end up overcarbed and if the pressure gets to high or the bottle is weak.

Of all the beer that I have bottled over the years I have had one bottle bomb.

you can check out some more here. http://www.homebrewtalk.com/f35/does-pr ... on-162761/

[Chewy]

)

[Tim Hall]

Chewy,

As long as you let the fermentation complete before adding priming sugar, this won't happen. It sounds like you had way too much fermentable left at the time of bottling, or you added too much priming fermentable. It would take a heck of a lot of pressure to blow up a champagne bottle.

The principle difference between ginger beer and champagne is the degree of dryness. Champagne should not explode on you because the ferment plays out dry (or the yeast poops out due to alcohol content). Ginger beer will always have residual sugar and low alcohol, so the yeast can keep going for a long time after bottling.

[Chewy]

this is LAB not yeast

[elektrogeist]

I've been brewing my own beer and other bottle carbo beverages now and never had a problem with exploding bottles, ever. The only case where you might get it is if something gets into the beer inbetween the fermentation tank and bottle, certain 'wild' yeasts will cause much more carbonation buildup than normal brewers yeast. Lot of Belgian ales get this from their lax use of certain wild organisms in brew, but hey it makes for some really tasty beer!
Interesting thoughts on the shape of the fermenting vessel, but true it probably doesnt make any difference in 5 gallon batches. Only time I've had trouble with a top blowing off is during the initial fermentation, always use a blow-off hose!