I just popped open a bottle of Maudite, and a question came to mind. I know that Maudite is a refermenting beer, that is, the fermentation process finishes in the bottle. A few friends have told me that although the label says the beer is eight percent alcohol, after opening the beer, it continues to ferment, which increases the level of alcohol. It’s a delicious brew, and I’ll continue to enjoy it, but does it really get stronger after you open the bottle? I would think that the increased alcohol content would adversely affect the flavor of the drink, but I can notice no distinct difference in a fresh pint compared to one that has sat for half of an hour or so.
I don’t know the particular beer you’re referring to but most beers that continue to ferment in the bottle do so before you open the bottle, not after.
The way it is done is that the beer is brewed and fermentation stops when the yeast in the mix runs out of sugar to convert into alcohol.
With most beers the process stops there and the beer is bottled and shipped off to you. With “fermented in the bottle” beers a little bit of sugar is added to the beer as it is bottled and the yeast ferments this extra sugar between bottling and consumption (it’s usually only a little bit of sugar, say a teaspoon per bottle). By the time the beer gets to you, the extra sugar is well and truly fermented and the process has stopped again.
Fermentation is an anerobic process. So when you open the bottle you expose it to oxygen and fermentation shouldn’t occur anymore. Of course, I don’t know if yeast is even capabale of aerobic respiration, so, I don’t know if the oxygen would even matter to the yeast. But I think it does… so when you open a bottle fermentation should stop completely.
As a half-assed homebrewer who has had a couple too many this evening: I think fermentation CAN occur with surrounding oxygen, but you don’t WANT it to as oxidation makes beer taste very very funky-- you need some oxygen initially early in the process (I think it is a tad later in the fermenting that oxygen becomes a problem). In the larger vat fermentation the scummy stuff is left on top as a kind of buffer from the air. But yeah, the bottle fermentation just adds a bit of carbonation-- they usually add a very neutral tasting sugar like dextrose, or more malt. The yeast at the bottom of a bottle of Maudite may be capable of being restarted-- homebrewers sometimes harvest Chimay yeast for their own beer. I think a beer like that COULD be restarted but would be dangerous-- too much stuff could contaminate it. You’d have to add more sugar and warm it up. A couple of hours wouldn’t make much of a difference.
Fermentation can only continue until the yeast has either eaten up all the sugar, or is killed off by excess alcohol. You can only get to a certain level of alcohol via fermentation; I forget the exact number, but I think it’s about 15 to 20%. To reach a higher level of alcohol, you’d have to distill the beer.
As to the alcohol changing the taste of the beer, well, ever had malt liquor? Good malt liquour that is, like Dinkel Acker (not Colt 45).
As a very amateur home brewer, I’ll add that refrigeration will slow down or stop the fermentation process. Before use in fermentation, yeast is stored in a refrigerator to keep it “fresh” but not active. I don’t have my lists in front of me but I think the recommended fermentation range for most ales is in the 60s F, and the lagers are perhaps in the 50s? When I pour the beer out of the fermentation tub into bottles, I add a small amount of sugar to each bottle (as Motog and capybara mentioned) and let it sit for a couple weeks to finish fermenting; only after that point do they get refrigerated.
So if the beer that you’re drinking is chilled (I’m not familiar with the one you mention), I don’t think it’d sit around long enough to warm up into a recommended fermentation temperature range - at least not for an amount of time that would do any good. The homebrews that I’ve made usually ferment for a month total before I refrigerate the bottles.
Another homebrewer checking in…it’s doubtful that the alcohol level is increasing…the alcohol level is pretty much set after primary fermentation. Further bottle “conditioning” contributes to flavor and carbonation, but not really to alcohol level.
usually…the alcohol level kills off much of the yeast anyway (which is why champagne yeast, a more alcohol tolerant strain, is then added later to goose the alcohol level even more in high alcohol brews like barley wine)
I’ve had Maudite and several other of the Chambly brewery’s Belgian-style beers (Blanche de Chambly, La Fin du Monde). All of these are re-fermented in the bottle. This process is essentially the same as the one which turns wine into sparkling wine (by the traditional methode champagnoise).
Apart from being extremely undesirable, as several posters have pointed out, I think it very unlikely that a bottle-fermented beer would continue to ferment once opened. When the yeast in the bottle runs out of fermentable sugar, it dies and eventually breaks down (autolyzes). The lees at the bottom of the bottle are mostly dead yeast cells, not live ones. (The lees in sparkling wine made in the traditional way are removed by a process called riddling.)
I suppose if you got to the beer shortly after it was bottled – that is, while the yeast was still alive and doing its thing – you might end up with live yeast in your glass, though I doubt the brewer releases the beer until the secondary fermentation is complete. And I wonder whether the fermentation would proceed quickly enough to be noticeable in your glass? … Ah, in preview, I see from Ferret Herder’s post that the answer is probably “no”.
Guy Propski, I think the maximum alcohol level attainable by natural fermentation is ~16-17%.
I just wanted to add here that I’ve had some of my homebrew before this process is complete. It’s not desireable to do this - the beer doesn’t taste bad, but it doesn’t taste good either. There’s something of a cidery taste from the unused sugar, and the carbonation just isn’t what you’d expect. I’m at the point where I can tell just from the sound when I uncap the bottle if it’s fermented long enough.
…because if it is a bottom-fermenting strain, then I’m thinking that the presence/absence of oxygen wouldn’t matter, and opening the bottle would not have the effect of re-starting fermentation (as the OP asked).
I haven’t gotten to secondary yeast additions in my brewing yet - I merely add a little sugar for the flavor and carbonation, like beagledave mentioned.
Actually, it has to be anaerobic (like, duh, Jerevan!) or it couldn’t ferment in the bottle. Harmonix spoke on this point earlier.
Harmonix, I think you are partly correct. The yeasts used for lagers, wines and bottle fermentations are anaerobic (bottom-fermenting), so presumably the presence or absence of oxygen is irrelevant. These yeasts convert sugars to ethanol and do not result in additional flavor components. Those used for ales and sherries are aerobic (top-fermenting), and incorporate oxygen in the fermentation process to produce the esters which give ales their distinctive “fruity” flavors.
Last I heard, Samuel Adams Utopias MMII was the world’s strongest beer at 24% alcohol by volume. They got it up that high by using a special yeast strain and a long aging process. Don’t expect to find it next to Schlitz in the convenience store…it retails for $100 a bottle and only 3,000 were produced.
Your friends are idiots. They probably think that whiskey ages in the bottle? Refermentation is a fancy word for saying “naturally carbonated”. It simply means that either a small amount of malt extract or corn sugar was put into the bottle at a certain point to continue the fermentation process, or it was bottled before fermentation was complete, to get the by-product… CO2, which makes the pretty bubbles.
Opening a bottle of naturally carbonated beer does not jack up the alcohol level. Once the fermentable sugars are gone, fermentation stops. Adding oxygen doesn’t matter if there is nothing for the yeast to eat (sugar). And if there is something for the yeast to eat, they are going to chow down whether the cap is on or not. By the time you pop the cap, fermentation is complete.