How do different volumes of CO2 affect flavor?

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mthelm85

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I know carbonated beer tastes better than flat beer, but why? How do different carbonation levels affect the taste of beer? Each style has a recommended level of CO2 so how would the flavor differ if you carbed a beer to half (or less) the recommended level and vice versa?

I haven't found any answers to these questions and I would like to understand this. Please help!
 
CO2 and water create carbonic acid. Ever drink Seltzer water? It's bitter!

The more CO2, the more carbonic acid, the more bittering.

Otherwise, it's a textural phenomenon. The main difference between wine and champagne (aside from grape varietal) is CO2 and yet, the bubbly is percieved as lighter.

Thus, the more bubbles, the lighter the percieved textural component.
 
You must not drink many English styles, flatter can be better. I really believe that most keggers love to over carbonate their beer, with some styles you destroy the flavor with overcarbonating.

_
 
Gila... Is right. Carbonic acid is produced when Co2 is introduced to beer, this affects the flavor and body of the beer.

I also agree with wildwest, I have an imperial stout right now that I do not fee like bottling and it is amazing as it is.
 
You must not drink many English styles, flatter can be better. I really believe that most keggers love to over carbonate their beer, with some styles you destroy the flavor with overcarbonating.

_

Flatter can be better, I agree. I don't even add priming sugar to my ESB as I like it to be carbed to about 0.75 volumes but I carb most of my English browns to about 1.5. Those are the exceptions, however. I think the vast majority of styles taste better when carbed at 1.5 volumes and up. The real purpose of the post though was to learn how carbonation affects flavor. Why does an ESB taste better with only 0.75 volumes of CO2 as opposed to 2.0? I know it does, I just don't know why.
 
CO2 and water create carbonic acid. Ever drink Seltzer water? It's bitter!

The more CO2, the more carbonic acid, the more bittering.

Otherwise, it's a textural phenomenon. The main difference between wine and champagne (aside from grape varietal) is CO2 and yet, the bubbly is percieved as lighter.

Thus, the more bubbles, the lighter the percieved textural component.

So carbonic acid makes the beer more bitter but is that all that's going on? When I taste a beer after it's carbed up the flavors seem to "pop" and it just tastes better. Could it be that the CO2 bubbles affect the way that your taste buds perceive the flavors? It seems to me that carbonation brings out flavors that aren't as noticeable without it. There has to be something more going on here but I know absolutely nothing about the anatomy/physiology of the human tongue!

I guess I could be satisfied just knowing the proper levels of carbonation for the different styles but I'm hoping someone here in the Brew Science forum will come through with a scientific explanation lol
 
I also agree with wildwest, I have an imperial stout right now that I do not fee like bottling and it is amazing as it is.

I just bottled my imperial stout last weekend. I don't know why i carbonated it. I bottled two straight from the fermentor. Those didn't last.

i'm drinking a porter that our club members brewed, and we put it in a oak barrel that previously had port wine. I accidentally overcarbed it, and it was just a mess. brought it back down to like 1.5 vols and it's incredible.

i think carbonation "spreads" flavors quicker to your tongue, or at least activates your taste buds better. i have nothing to back this up.
 
LOL Before I write this I should probably just start a thread in Drunken Ramblings called "My Opinions" because I'm an amateur. Anything I say can be refuted by scientific fact I'm sure.

Anyway...

There are charts that provide guidelines for the best carbonation levels according to the beer style. I suppose if you want to replicate a beer perfectly to the style, carbonation wise, and along with that the recipe, you must follow those instructions. They're the gospel. Much effort went into creating that beer, gathering the data and putting into print.

However, I find myself asking a question. When these beers were first created was it a pure understanding of what carb levels worked best with which ingredients to make a tasty beer or matter of circumstance? If you keg it's pretty easy to control carbonation levels. The more you control the farther away, or closer get to the original.

I'm either to new at brewing or just don't really give a poop if my carbonation is exactly perfect for the style. If it taste good to me, then I'll consider it a good beer. Same goes with "great", "awesome" and "perfect". I'm a homebrewer and haven't been completely bit by the perfection bug but know when beer taste good to me.

Brewing is not my career and I'm always learning something new to make better beer. This is a hobby I enjoy and more often than not the results of my work are enjoyed by me and friends. Making the beer with friends is a wonderful part of the whole process. There is always the possibility that some time down the road I'll look at this post and think to myself a naive idiot. Doubtful.

"Drink to the Foam!"
 
So carbonic acid makes the beer more bitter but is that all that's going on?

Bitter? Acid tastes sour to most folks. Carbonated water certainly does. Apparently manufacturers pump in enough CO2 to the point that pH is as low as 3 -4. Accordingly some bottlers add alkali to their products in order to neutralize the sour taste. I guess if they added enough alkali to raise the pH into the alkaline range the product could taste bitter (low pH ~ sour taste; high pH ~ bitter) but that's sort of self defeating as it causes CO2 to convert to bicarbonate. I've certainly never tasted bitter carbonated water. Salty, yes.

When I taste a beer after it's carbed up the flavors seem to "pop" and it just tastes better.

Tartness does increase the refreshing qualities of beverages and this could be part of how carbonation works. Note that lagers which usually finish at higher pH's tend to be carbonated more than ales which naturally have a lower pH.

Could it be that the CO2 bubbles affect the way that your taste buds perceive the flavors?
I saw a paper recently but can't remember where or much about what it said except for the single finding that obviously made an impression on me more than the rest of it. That finding was that the tiny CO2 bubbles released when a cold, carbonated beverage hits your warm mouth interact with pain receptors in the tongue and it is this that leads to the pleasurable sensations associated with drinking beer, soda or sparkling wines. I immediately thought of an analogue with pepper. It works in a similar way. Capasaicin is an irritant, as are the CO2 mini bubbles. It too influences the way foods taste and clearly that's why it is used so widely. IOW it's not all about heat with pepper and it's not all about spritz with CO2. Both bring out flavor.

It seems to me that carbonation brings out flavors that aren't as noticeable without it. There has to be something more going on here but I know absolutely nothing about the anatomy/physiology of the human tongue!

I think you are right as noted above but there is certainly more to it than I have any clue about. I wish I could remember where I saw that paper.


I guess I could be satisfied just knowing the proper levels of carbonation for the different styles but I'm hoping someone here in the Brew Science forum will come through with a scientific explanation lol

I would hardly consider my comments a complete scientific explanation.
 
Okay, so here are a few scholarly works on the subject:
http://www.sciencedirect.com/science/article/pii/S0022030291783823
Abstract: Raspberry, strawberry, peach, and root beer flavored milks were carbonated at subthreshold, low, and high carbonation levels with mean carbonation volumes of <.60, .74, and 1.42, respectively. The effect of carbonation on perceived aroma and flavor by mouth attributes was determined through evaluation by a trained panel. Panelists detected a significant difference in carbonation intensity between the high carbonation level and the subthreshold and low carbonation levels. Carbonation significantly suppressed cooked milk aroma and flavor by mouth at the low and high carbonation levels, but CO2 significantly enhanced sourness and astringency at the high carbonation level. Chalkiness and bitterness were rated significantly higher at the high carbonation level than at the low or subthreshold levels.

http://chemse.oxfordjournals.org/content/23/4/397.short
Abstract: Previous studies of the effect of carbonation on taste perception have suggested that it may be negligible, manifesting primarily in increases in the perceived intensity of weak salt and sour stimuli. Assuming CO2 solutions in the mouth stimulate only trigeminal nerve endings, this result is not altogether surprising; however, there are neurophysiological data indicating that CO2 stimulates gustatory as well as trigeminal fibers. In that case, carbonation might alter the quality profile of a stimulus without producing substantial changes in overall taste intensity—much as occurs when qualitatively different taste stimuli are mixed. To address this possibility, subjects were asked to rate the total taste intensity of moderate concentrations of stimuli representing each of the basic tastes and their binary combinations, with and without added carbonation. They then subdivided total taste intensity into the proportions of sweetness, saltiness, sourness, bitterness and ‘other taste qualities’ they perceived. The addition of carbonation produced only small increases in ratings of total taste intensity. However, rather dramatic alterations in the quality profiles of stimuli were observed, particularly for sweet and salty tastes. The nature of the interaction is consistent with a direct effect of carbonation/CO2 on the gustatory system, although the possibility that at least some of the observed effects reflect trigeminal-gustatory interactions cannot be ruled Out.

http://www.sciencemag.org/content/326/5951/443.short
Abstract: Carbonated beverages are commonly available and immensely popular, but little is known about the cellular and molecular mechanisms underlying the perception of carbonation in the mouth. In mammals, carbonation elicits both somatosensory and chemosensory responses, including activation of taste neurons. We have identified the cellular and molecular substrates for the taste of carbonation. By targeted genetic ablation and the silencing of synapses in defined populations of taste receptor cells, we demonstrated that the sour-sensing cells act as the taste sensors for carbonation, and showed that carbonic anhydrase 4, a glycosylphosphatidylinositol-anchored enzyme, functions as the principal CO2 taste sensor. Together, these studies reveal the basis of the taste of carbonation as well as the contribution of taste cells in the orosensory response to CO2.
 
The findings in the first paper above are really interesting but the paper isn't free so that sucks. You'll note that the abstract says that carbonation SIGNIFICANTLY suppressed not only flavor but AROMA (of cooked milk) which I find really interesting and it makes me wonder if the same thing happens in beer. They also state that the CO2 significantly enhances sourness and astringency at 1.42 volumes so imagine the difference between a beer carbed at 1.0 volume and a beer carbed at 2.5 or 3.0 volumes....
 
They also state that the CO2 significantly enhances sourness and astringency at 1.42 volumes so imagine the difference between a beer carbed at 1.0 volume and a beer carbed at 2.5 or 3.0 volumes....

I don't want to belabor the point -- there's already two other threads about carbonation going on this week alongside this one -- but it's another process point to consider when you're controlling pH -- or attempting to control pH. The idea (in my case, at least) that if your mash pH is below normal (i.e., 5.2-5.3 @ room temp) that carbonation will most likely impact the finished product taste-wise. Until now, I hadn't seen these two variables together in a forum discussion. (Which maybe means that I'm late to the party, but I'm glad it's finally becoming clearer in my mind now that I've encountered several simultaneous discussions here in recent days.)

Again -- in my case -- had I thought this through a little bit better (and avoided the too-low mash pH at room temp in the first place) I might have decreased my carbonation at bottling time to avoid a too-distinct sour taste due to the carbonic acid. Not sure if this would have made a big difference, but I'd rather have a slightly undercarbonated brew with full(ish) flavors as opposed to a normally carb'd beer with slightly -- very slight -- sour flavors.

As it stands, I've got about 4 or 5 brews that are drinkable but not where I want the flavor to be due to the combination of carbonation an mash pH. They're borderline -- not by any means bad, but not as good as I'd hoped -- but they don't have the full malt profiles that I expected. More brews are in the fermenter (with increased pH @ mash time) -- and I'm brewing again in a few days -- so I'll report back.

Great threads!
 

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