Acetaldehyde In Wine and Spirits...

It is widely known that when you leave wine in a pertially opened btl, it starts to oxidize, with one of the prime oxidations being oxygen acting on ethanol to produce Acetaldehyde. Acetaldehyde is the primary sensory component you get in baked sherries and Madeiras. Yet you can leave a btl of vodka or gin open for several yrs w/o the formation of Acetaldehyde.
So...why is the production of Acetaldehyde occur in wine but not in spirits???
TomHill

It is widely known that when you leave wine in a pertially opened btl, it starts to oxidize, with one of the prime oxidations being oxygen acting on ethanol to produce Acetaldehyde. Acetaldehyde is the primary sensory component you get in baked sherries and Madeiras. Yet you can leave a btl of vodka or gin open for several yrs w/o the formation of Acetaldehyde.
So...why is the production of Acetaldehyde occur in wine but not in spirits???
TomHill

Acetaldehyde is already in wine from yeast, acetic acid, and phenolics. The oxidation process adds to it.

Spirits also contain acetaldehyde, as far as I know. Why we don't smell the "maderization" in spirits over time might have to do with alcohol volume, lack of phenolics, distillation, Mark Lipton, where are you?

Acetaldehyde is already in wine from yeast, acetic acid, and phenolics. The oxidation process adds to it.

Spirits also contain acetaldehyde, as far as I know. Why we don't smell the "maderization" in spirits over time might have to do with alcohol volume, lack of phenolics, distillation, Mark Lipton, where are you?

Thomas,
Granted...acetaldehyde is already present in both wines & spirits. But my guess is that it's well below the sensory threshold in nearly all of them....save the baked sherries & madeiras and a few other wines.
When an oxygen atom is out prowling the singles bars, looking for an innocent ethanol molecule to hook up with...how does it tell if that sweet-looking ethanol molecule is of the wine or the spirits persuasion???
Tom

Tom

Acetaldehyde is already in wine from yeast, acetic acid, and phenolics. The oxidation process adds to it.

Spirits also contain acetaldehyde, as far as I know. Why we don't smell the "maderization" in spirits over time might have to do with alcohol volume, lack of phenolics, distillation, Mark Lipton, where are you?

Thomas,
Granted...acetaldehyde is already present in both wines & spirits. But my guess is that it's well below the sensory threshold in nearly all of them....save the baked sherries & madeiras and a few other wines.
When an oxygen atom is out prowling the singles bars, looking for an innocent ethanol molecule to hook up with...how does it tell if that sweet-looking ethanol molecule is of the wine or the spirits persuasion???
Tom

Tom

Tom,

I repeat:
"...might have to do with alcohol volume, lack of phenolics, distillation, Mark Lipton, where are you?"

Interesting question. Ethanol is pretty stable on its own, so something else in the wine would seem to be a contributor to the process. A Google search brought up this link. It indicates that hydrogen peroxide in the wine, which is a by-product of the oxidation of phenolics, is what oxidizes the ethanol into acetaldehyde.

Spirits also contain acetaldehyde, as far as I know. Why we don't smell the "maderization" in spirits over time might have to do with alcohol volume, lack of phenolics, distillation, Mark Lipton, where are you?

Here I am, Thomas... My guess (emphasis on guess) is that the higher alcohol level in distilled spirits simply masks the smell of the acetaldehyde. Also, if there are any tannins present from oak aging, they'll react with acetalehyde fairly rapidly (aka "anaerobic" polymerization of tannins).

Mark Lipton

Spirits also contain acetaldehyde, as far as I know. Why we don't smell the "maderization" in spirits over time might have to do with alcohol volume, lack of phenolics, distillation, Mark Lipton, where are you?

Here I am, Thomas... My guess (emphasis on guess) is that the higher alcohol level in distilled spirits simply masks the smell of the acetaldehyde. Also, if there are any tannins present from oak aging, they'll react with acetalehyde fairly rapidly (aka "anaerobic" polymerization of tannins).

Mark Lipton

Only a guess? Since it's one of my guesses, I feel like I know something

I defer in all matters to Prof. Lipton, but in this case, I think there are special things going on--oxygen doesn't react very quickly with pure ethanol, so your old vodka still tastes the same as it did new. But if there are intermediates like his phenolic tannins, you can pass those electrons off a lot quicker. So wine gets more than vodka. (although I don't find myself noticing acetaldehyde in wine so often (maybe bottles don't sit around that long?)).

The best way to do it is biochemically, natch. Acetobacter and an open wine barrel will get you more acetaldehyde than most anything else.

Tom,

I think that SFJoe has hit on the answer. The acetaldehyde associated with wine spoilage doesn't come from direct oxidation of ethanol. It comes about by bacterial action. Acetobacter and the other organisms involved are aerobic, so oxygen is required both to introduce them into the wine in the first place and for them to perform their conversion of ethanol first to acetaldehyde, then acetic acid, and finally CO2 and water. This doesn't happen in spirits because the ethanol concentration is too high for the bacteria to live.

-Paul W.

I defer in all matters to Prof. Lipton, but in this case, I think there are special things going on--oxygen doesn't react very quickly with pure ethanol, so your old vodka still tastes the same as it did new. But if there are intermediates like his phenolic tannins, you can pass those electrons off a lot quicker. So wine gets more than vodka. (although I don't find myself noticing acetaldehyde in wine so often (maybe bottles don't sit around that long?)).

Absolutely, you modest thing, you. I believe that it's actually the hydrogen peroxide produced from the reaction of oxygen and phenolics that's responsible for the oxidation of ethanol to acetaldehyde. However, I was responding to the question of why the acetalhyde in spirits wasn't as noticeable as that in wine, taking it for granted that it was there. If it's not, then your observation is quite germane.

The best way to do it is biochemically, natch. Acetobacter and an open wine barrel will get you more acetaldehyde than most anything else.

Are you sure about that? I'd think that acetobacter would, like our livers, take on virtually all of the acetaldehyde to acetic acid fairly rapidly. Acetaldehyde is toxic to most organisms in any significant quantity.

Mark Lipton

So...why is the production of Acetaldehyde occur in wine but not in spirits???

If an alcoholic drinks the spirits first, the acetaldehyde from them the next day can easily be detected from his skin and breath.

Yes I agree with you Paul, that acetaldehyde is mainly formed during alcoholic fermentation. Some wild yeast strains (the ugly ones) can produce large amounts of acetic acid and ethyl acetate. Wine yeast strains will produce varying amounts of acetic acid (low, med, high level producer of VA). It is also a product of subsequent oxidation of ethanol. Of course this does not mean that the only source of an O atom has to be O2. Sulfur dioxide in the presence of ethanol with metal catalysis present can cause the oxidation of ethanol. As Mike has posted in his post- hydrogen peroxide (the result of oxidation of phenolics present in the wine) can also cause the oxidation of ethanol. (“Direct oxidation”-I’m not sure what this means).
I agree that acetaldehyde is also an intermediate product of microbial metabolism of acetic acid. As far as acetic acid bacteria and other micro-organisms such as ML Bacteria (LAB) and Brettanomyces they convert both ethanol and sugar into acetic acid. But generally however this is only a problem when there is a significant amount of sugar present and the micro-organism is at a "critical population" and can tolerate the alcohol content.
Tom before the “mash” is distilled I believe the VA components are removed. Besides the “first sample” of distillate collected, I think it’s called “the head” is discarded. Another thing to consider is the material that the still is made out of, mainly copper. We all know what copper does to sulfur containing compounds

Salute

So...why is the production of Acetaldehyde occur in wine but not in spirits???

If an alcoholic drinks the spirits first, the acetaldehyde from them the next day can easily be detected from his skin and breath.

Well, yes, but that involves the production of acetaldehyde in winos, not wine!

The best way to do it is biochemically, natch. Acetobacter and an open wine barrel will get you more acetaldehyde than most anything else.

Are you sure about that? I'd think that acetobacter would, like our livers, take on virtually all of the acetaldehyde to acetic acid fairly rapidly. Acetaldehyde is toxic to most organisms in any significant quantity.

Mark Lipton

The toxicity is probably why our noses have evolved to detect acetaldehyde so well.

As is the case with the human liver, I would expect that acetobacter's alcohol dehydrogenase (which converts ethanol to acetaldehyde) works significantly faster than aldehyde dehydrogenase (which converts acetaldehyde to acetic acid). And acetobacter causes considerable buildup of acetic acid in its vicinity before converting it to CO2 and water via the Krebs cycle.

So when acetobacter starts to infest wine, I'd expect acetaldehyde to be detected first, even though it's in trace amounts. Eventually the smell of acetic acid will overwhelm the acetaldehyde aroma, and you get vinegar smells. Then even the vinegar weakens and goes bad as the acetobacter finishes the conversion to CO2 and water.

-Paul W.

The best way to do it is biochemically, natch. Acetobacter and an open wine barrel will get you more acetaldehyde than most anything else.

Are you sure about that? I'd think that acetobacter would, like our livers, take on virtually all of the acetaldehyde to acetic acid fairly rapidly. Acetaldehyde is toxic to most organisms in any significant quantity.

Mark Lipton

The toxicity is probably why our noses have evolved to detect acetaldehyde so well.

As is the case with the human liver, I would expect that acetobacter's alcohol dehydrogenase (which converts ethanol to acetaldehyde) works significantly faster than aldehyde dehydrogenase (which converts acetaldehyde to acetic acid). And acetobacter causes considerable buildup of acetic acid in its vicinity before converting it to CO2 and water via the Krebs cycle.

So when acetobacter starts to infest wine, I'd expect acetaldehyde to be detected first, even though it's in trace amounts. Eventually the smell of acetic acid will overwhelm the acetaldehyde aroma, and you get vinegar smells. Then even the vinegar weakens and goes bad as the acetobacter finishes the conversion to CO2 and water.

-Paul W.

I've tasted old, bad vinegar, and it is a lot like water, but water from a place you wouldn't want to slurp...