Oxygen and wine

Hi Alex,

The object isn't really to keep oxygen away, but to introduce small controlled amounts of oxygen at certain intervals which helps soften and mature the wine. This is true especially of reds. The bucket is a bad idea in practice, even though in theory it would be OK. The reason is that between these controlled additions of oxygen during racking and topping, you DO want to keep all oxygen away. It would be very difficult to sparge the headspace of a bucket and be sure that all the oxygen was gone. If the bucket is plastic, oxygen will diffuse through the plastic and CO2 will diffuse out. Plasticizers may also get into the wine with long term storage in plastic. Long term storage is best done in glass, wood or stainless steel, period.

Regards,

Yes, regarding your question about the oxygen and CO2. You want to prevent it from oxydizing. What your saying is theorhetically true but I'm sure that you would get anyone to recommend doing it that way. But who knows, you're may be onto something. Good ideas are not always endorsed right away. I.e. snowboarding, trains, planes etc. Good luck!

That may be the way of the future but not like you are thinking. There is a company out of Australia that makes a special plastic bag, especially formulated to be used with wine. Some wineries are using them as inserts into large plastic buckets to ferment and even to age wine. But they are only made in large sizes, much too large for home winemakers. I wish they would make 5 to 25 gal sizes. I would like to experiment with them.

In message , John DeFiore writes

I have asked this before but with no reply. I was recommended by my local home brew shop to use the 5 gallon plastic carboys instead of glass. I have also read of many people on this newsgroup using these. Why is it that they sell these plastic carboys and yet apparently they are not very good for the wine? I am quite worried that my next wine will be ruined if I use these instead of glass. I have always used 1 gallon glass demijohns but 5 gallon versions are too pricey .

One of the main purposes of racking is to separate the wine from the lees, the particulate matter that has settled to the bottom of the carboy (or other container).

Filter> Is the purpose of racking to just filter and stir a little? If so,

Hi Clyde,

Hope all is well with you- Under the category of "you learn something new every day", I stand corrected on the plastic issue. I can see where HDPE could be a good material, but I would have been chicken to try it unless somebody else (like you) had tried it first. I was originally thinking more of some random 5 gallon bucket that might or might not be food grade. So a food grade plastic carboy is probably fine.

Regards,

John

Humm. SO2 levels. Perhaps I need to visit the Jack Keller site again, but could someone summarize what the relationship of the SO2 levels is to the quality and chemistry of making wine?

Oxygen: At the start of fermentation, the yeast uses oxygen to multiply rapidly and start converting the sugar to energy (for reproduction) and free CO2 (waste byproduct). This is called aerobic fermentation.

CO2: This does not really play a role in wine making except to displace the oxygen so that they yeast starts to convert sugar into CO2 (waste byproduct) and alcohol. This is anerobic (sp?) fermentation. In beer making, a little more sugar is added at the end of fermentation when bottled to carbonate the beverage.

SO2: Generally this is what I would call an antseptic. You put something in the wine at the beginning to kill off or at least slow down any beasties that live in there to give more of a chance for the yeast you put in there to take over.

Am I missing something more with the SO2?

I also understand that there is some other chemical reactions that can take place along the way. These would include that during long-term storage, oxygen or light can combine with the molecules that provide fruit taste to break them down into other things that do not impart a good taste to the wine.

In the absence of oxygen, does aeration matter? Would it matter if I stirred up the wert (if it can be called wert at this point....) if I could guarantee that there was no oxygen present? Since CO2 and SO2 are gasses, stirring up a solution containing them will change the amout that is dissolved in the wine. I would think that CO2 levels would not matter. The SO2 level would depend on the question above.

On the light thing above, what is the part of the light that has an effect? I ask this because of stabelizing. When you stabelize, you kill pretty much anything in there by adding a chemical that does this and then either out-gasses or breaks down. My father just purchased a UV sanitizer for his well. What if I just ran my wine through this gadget in a clear tube? This should kill anything in it.

On another note, the buckets that I have gotten ahold of are food grade. They are used to hold Turkey seasoning at a plant I work in and have a sanitary lid with a full o-ring gasket around the top. They hold back most light, but you can still tell the level inside if you look really close. I store all my wine and beer making stuff in a basement inside a closet, so no light can get to anything except from a single light bulb.

Alex.

Alex, when small quantities of sulfur dioxide (SO2) are added to crushed grapes, the SO2 (1) deactivates the natural grape enzymes (polyphenoloxidase) that cause browning; it (2) inhibits many native yeasts; (3) it inhibits or kills many of the native bacteria; (4) improves color extraction from red grapes. When small quantities of sulfur dioxide are added to wine, it (5) scavenges dissolved oxygen and helps reduce wine oxidation; (6) it combines with acetaldehyde and removes oxidation odors; (7) it inhibits some types of yeast; (8) it inhibits or kills some types of wine bacteria.

Regards, lum

There is an interesting article in June-July edition of WineMaker Magazine that deals with this subject called "Phenolics Explained", Very interesting article. It also has an article about Jack Keller also.