- The flavor threshold for acetic acid is ~175 ppm, and unblended beer at Rodenbach may have ~2500 ppm.

- 1 acetic acid molecule and 1 water molecule can be created from 1 ethanol and 1 O2, by acetobacter or brett.

- if you convert that reaction into masses, it turns out *1 gram of oxygen can allow for the production of ~2 grams acetic acid*. (Of course it may be that not all the oxygen gets used to produce acetic acid, so this a maximum number.)

- Going further: 1 gallon of air has 1 gram of oxygen, which again may lead to as much as 2 grams acetic acid, which in 5 gallons of beer is only 105 ppm acetic acid. To get to the taste threshhold you'd need (at least) 2 gallons of air. To get to the 2500 ppm mark you'd need (at least) 25 gallons of air. (over time)

- Raj Apte gives numbers for oxygen permeability of various fermenters, in terms of cc/L.year. You can multiply these by 2.8 to get "ppm acetic acid per year."*

- At least with the numbers Raj gives, only the HPDE bucket would get above the taste threshold in 3 years. I don't know how accurate these numbers are, of course. Different barrels in different state of repair, or with different closures, will probably vary wildly in their permeability.

I think the value in these numbers/calculations is that they at least allow some reasonable way of approximating stuff, even if they aren't perfect. The numbers suggest you can't get appreciable acetic acid in carboys or even tight barrels unless you either vent the headspace often or close then in some non-airtight way. Anyone ever have an experience that's contrary to these predictions?

(Personally I'm kind of ambivalent about acetic, so I keep stuff tight.)

I agree that more oxygen than the math suggests must be getting into Rodenbach and La Folie. From pictures, it looks like the top of their tuns aren’t touched by the beer, so they wouldn’t be swelled up and airtight like the sides.

I’m not a big fan of acetic acid either, so I generally don’t worry about it much. For my next round of Flanders Reds a few people will all be brewing/aging beers for an eventual group blend. My plan is to leave some of my wort after primary fermentation in a growler with aluminum foil over the top. I figure after a year it will be very vinegary and I can blend it to taste with the rest of the lactic beer. I figure once its bottled there will be no O2 and thus a stable acetic character.

I recently read, though, that it may be possible to reduce the vinegar taste: in Farmhouse Brews, Markowski mentions that brewers would add crushed eggshell to beers in order to draw off vinegar. He does not, however, go into too much detail on this point. Since I still have over five gallons of the culprit beer, I would love to reclaim it with a simple rack onto eggshells.

Does anyone know anything about this possibility? Thanks in advance.

You may experiment with CaCO3 on a small amount of brew, but I'd save the eggshells for your tomato plants :)

Eggshells are 95% calcium carbonate (an alkali). They react with, and are dissolved by, acetic acid and you can make a shell-less "naked egg" by soaking an egg in vinegar.

So, you could add eggshells or calcium carbonate to your beer (you may already have food grade calcium carbonate around for brewing purposes), and it will react with the acetic acid to form water, CO2, and calcium acetate. The wikipedia page claims that ethanol and a calcium acetate solution will form a "semisolid, flammable gel":

http://en.wikipedia.org/wiki/Calcium_acetate

I guess the point is that you can add eggshells or CaCO3 and react out some of the acetic acid, at the expense of creating a gel whose brewing properties are not well known to most of us. On the other hand its a traditional technique, so maybe it's not that scary.

(Eggshells also have lysosyme, I believe, which inhibits some acid-producing bacteria. But, I think that's not the point in this case.)

Several sources give lambic as having 600-1000 mg/L acetic acid. Two acetic acid molecules (60 gm/mol) react with one calcium carbonate molecule (100 gm/mol). So, to strip 500 mg/L acetic acid out of a pure acetic/water solution, you'd need about 1.5 gm/gallon of eggshells or CaCO3.

Beer isn't a pure acetic acid solution and there's lots of crap in there that can mess things up, but that's the type of level you might need.

- Flaming Homer?

Love that Simpson's episode: "I don't know the science of it, but fire made it gooooood".

I don't really have much to lose other than a few gallons of beer that no one would want to drink as is. If I can't drink it, maybe I can start campfires with it.

It is no longer acetic, even in the slightest. The eggshells no longer exist in their original form. This stuff actually tasted pretty good on its own, still mildly acidic but only in the most gentlemanly fashion, so I racked it onto several pounds of freshly picked cabernet sauv. grapes. Have not yet tried to ignite the remaining napalm, but that will happen in time.

Oddly enough, there is nothing that I would describe as chalky in the taste -- I did use a fairly light load of eggshells/gallon (12 eggshells/4 gallons). In fact, the flavor is far less acidic than I would have expected for a beer fermented for 3-years in direct contact with the local air, and probably far less so than it was when I added the CaCO3 -- I found the flavor and aroma objectionable then, but don't now.

Magic devinegarizer?

BTW Jean-Louis also said that with time, a lactic-infected beer will get less sour even without eggshells. He said there were old-time brewers who would brew saison in winter not to be consumed that summer, but rather the summer of the year after (~18 months between brewing and consumption). The extra year of aging reduced the sourness.

Baums -

I can say from experience that what Jean-Luis speaks of, about acidity dying down over time, is true. My first sour saison from last summer was very lactic when first bottled...it was described as mouth-puckeringly acidic by the judges from the competition I entered it in (although I like that kinda sour myself). Now it's about a year and quarter old, and the last time I tried one (a month or two ago) the acidity has definitly mellowed significantly, much more balanced than when it was first bottled. I've also noticed a mellowing of acidity in my kriek that was bottled in January.

I've often read, in a homebrewing context, that things will sour more over time, but I've also read about the aging of gueze in order to tame it's sometimes overly sour profile.... I'm leaning towards the latter as opposed to the former these days.... perhaps it has something to do with the amount of CO2 dissolved in the beer from preventing it to vent off? It seems as though aging in carboys or barrels tends to increase acidity while once it is bottled the acidity eventually mellows... any thoughts?

I boiled those puppies, then peeled the shells off, and threw them in. Disappointed in apparent lack of napalm, but pleased with de-acetification (Which, of course, could have just been from those extra 6 months in the closed fermenter).

MarkO's test is so interesting to me that in the interest of SCIENCE I will go back and add a little eggshell to half the bottles to see what happens. Think it's a waste of time? That's fine. My wife and daughter like their hardboiled eggs, so shells are plentiful, and I just want to see what happens. Will report back if there is interest.

Although, considering I was near to dumping it for all the vinegar, I suppose it had some degree of success. It's just not a beer for company, that's all.

THE WINE PRESS AND THE CELLAR.

A MANUAL FOR THE WINE-MAKER AND THE CELLAR-MAN.

BY E. H . RIXFORD.

SAN FRANCISCO :

PAYOT, UPHAM & CO.

NEW YORK :

D. VAN NOSTRAND.

1883.

page 144

Machard's Treatment. Machard says that the most successful

treatment for sour wine employed by him, is that founded

upon the affinity of vegetable substances for acids, and that he

has succeeded beyond his hopes in completely removing the acid

from a wine which was so sour that it could not be drank without

seriously disagreeing with the person drinking it. This is

his method of proceeding.

He formed a long chaplet, six feet or so in length, by cutting

carrots into short, thin pieces, and stringing them on a cord.

This he suspended in the wine through the bung for six weeks,

and at the end of the time he did not find the least trace of acetic

acid, thereby accomplishing what he had for a long time in vain

attempted. He says that this is the only treatment that succeeded

with him, and he confidently recommends it to others. But he

advises that the carrots be left in the wine at least a month and

a-half , protecting the wine from the air. And he says that there

is no danger of injuring the wine by long contact with the carrots,

or by using a large quantity of them.

It had red wine for a short amount of time and is

recently dumped. When I got it, I smelled the interior,

I had my wife smell it as well. Both opinions were that

it smelled like vinegar. I spoke with the source person

and was told that he thought his employee had burned a

sulfur strip inside before shipping. My question is this,

can a barrel that held red wine and then had a sulfur strip

burned inside, give the mistaken aroma of something resembling vinegar?

Of note was the irritation of the olfactory resulting

in sneezing and sniffling....sulfur di-oxide remnants?

YES. I have also experienced this.

Thanks Baums I needed to hear that. but tell me, did

you use that barrel and if so, was it acetobacter?

How did the result of using that barrel flavor your end product?

I do not know if my barrel(s) have acetobacter in them (I have not done microbial analyses) but I always assume they do. I also assume that their activity is minimized because I do not allow large amounts of oxygen into the beer.