Oxygen

[justsipn]

Ok....what’s the scoop on this?

I first learned that once primary fermentation is done, oxygen is your enemy. That’s why you want to keep the carboy as topped off as possible with an airlock.

However, now I’m reading about barrels and how they are great , in part, because they allow for some micro oxygenation while the wine ages. I’ve read where natural forks do the same thing so they are better for red wines.

I’ve also read where a really good aged red wine can have more of a brown color due to micro oxygenation.

So, I’m confused. Why is it that oxygen is the enemy but in some situations, micro oxygenation is good?

Thanks in advance.

 

[sour_grapes]

IMHO, the answer is this: The dose makes the poison - Wikipedia

 

[user 36973]

Yes, oxygen can be both a friend and an enemy.

Wines that are tannic (ie. dry reds) benefit from micro-oxygenation via breathing through barrel wood, flex tanks or even carefully through carbonation-type stones in tank. The low amounts of oxygen result in the tannin polymerizing. This softens the wine by reducing the concentration of short-chained tannin molecules that we perceive as bitter while increasing the longer chain ones that we perceive as mouthfeel. The degree of tannin dictates the barrel time. Barrel choice also impacts the rate of oxygen transfer. French oak has tighter grain which lets more air in than American oak.

Of course too much of a good thing is bad. If more oxygen dissolves into the wine than the tannin can manage or if the wine has little tannin (e.g. white wines), the wine will oxidize causing aroma loss and feeding micro-organisms. The wine will brown as it oxidizes and various mostly unpleasant esters can be produced such as ethyl acetate (aka. fingernail polish remover) or acetaldehyde (aka bruised apple). In the worst case, acetobacter can produce vinegar and make the wine undrinkable.

So, care must be taken to ensure the wine is protected from oxygen even when aging in barrels. I find that my 53gal barrels evaporate about 1L of wine a month so I need to top them off regularly and stay up with sulfites, which I do every other month.

 

[justsipn]

Yes, oxygen can be both a friend and an enemy.

Wines that are tannic (ie. dry reds) benefit from micro-oxygenation via breathing through barrel wood, flex tanks or even carefully through carbonation-type stones in tank. The low amounts of oxygen result in the tannin polymerizing. This softens the wine by reducing the concentration of short-chained tannin molecules that we perceive as bitter while increasing the longer chain ones that we perceive as mouthfeel. The degree of tannin dictates the barrel time. Barrel choice also impacts the rate of oxygen transfer. French oak has tighter grain which lets more air in than American oak.

Of course too much of a good thing is bad. If more oxygen dissolves into the wine than the tannin can manage or if the wine has little tannin (e.g. white wines), the wine will oxidize causing aroma loss and feeding micro-organisms. The wine will brown as it oxidizes and various mostly unpleasant esters can be produced such as ethyl acetate (aka. fingernail polish remover) or acetaldehyde (aka bruised apple). In the worst case, acetobacter can produce vinegar and make the wine undrinkable.

So, care must be taken to ensure the wine is protected from oxygen even when aging in barrels. I find that my 53gal barrels evaporate about 1L of wine a month so I need to top them off regularly and stay up with sulfites, which I do every other month.

Thanks for the great reply.

So, I’m making a Malbec right now. If I can find a 6 gallon barrel and make a Merlot or Cabernet, I could top it off and end with sort of a Bordeaux blend. The oxygen would be at a low level and age the wine appropriately.

Of course, this is about 3+ years down the road.

 

[Venatorscribe]

Thanks for the great reply.

So, I’m making a Malbec right now. If I can find a 6 gallon barrel and make a Merlot or Cabernet, I could top it off and end with sort of a Bordeaux blend. The oxygen would be at a low level and age the wine appropriately.

Of course, this is about 3+ years down the road.

Thats a very good idea. I’m contemplating a similar blend. Malbec, Merlot and Cab Sav are made for each other. A beautiful combination/ blend. You won’t regret.

 

[user 36973]

Malbec, Merlot and Cab Sav are made for each

The holy trinity of wine! (Cab franc too...)

 

[justsipn]

Question....

When a really good commercial winery makes a Bordeaux blend like that, do they make the wine, age them separately then blend, or mix the grapes or must at the beginning and make the wine in one batch?

 

[user 36973]

When I visited Bordeaux a couple years ago, I recall that one of the winemakers met with on the left bank said that she blended AFTER aging as part of the final tasting. This way they could blend in more or less petit verdot as needed to balance the tannin profile from their cab sauv that year.

I'm sure each winery has their own procedure though.

 

[winemaker81]

When I visited Bordeaux a couple years ago, I recall that one of the winemakers met with on the left bank said that she blended AFTER aging as part of the final tasting.

My understanding is that is typical for commercial wineries, especially where they have dozens or hundreds of barrels, plus storage space.

I do field blends because of the opposite -- I don't have many barrels (or other containers) and I don't have the space. On the plus side, it gives me something to dream about.