Pressing question

[Wild Duk]

When you all press your grapes, how concerned do you have to be with oxidation. It appears in most videos I've watched that the juice just pours down splashing into a bucket.

I'm accustomed to be very careful when racking wine as not to splash to much..

 

[Runningwolf]

When I press, I add meta and enzyme at the same time for protection.

 

[Deezil]

Red wines are usually pressed at a low Brix level.. This means a couple things. First, they're saturated with CO2, from the fermentation that's already taken place.. And also, they arent fermented dry yet, so they'll create more alcohol and CO2 still. This CO2 helps to act as a buffer, as the grapes are pressed but i believe (dont quote me here, havent made red wine from grapes yet) they also add a small amount of k-meta to the pressing to keep oxygen at bay.

With white wine grapes, the pressing is usually done before fermentation so oxidation is less of a fear, but k-meta is used during the pressing so that oxidation doesnt get out of control. The yeast will actually mitigate oxidation damage done prior to fermentation, by using up some of the oxygen within the must, during the ferment.

Either way, when the juice/must hits the bucket - you probably wouldnt want to take a very big whiff because it'll be mostly CO2 or K-meta, depending on what you're handling...

Wine at the pressing stage is a bit different than wines that have been stabilized and are working on clearing - with those, you most definitely want to limit the amount of splashing/oxygen exposure because oxidation is a real fear when wine is just bulk aging.

Leaving it in the bucket for any extended amount of time is a different story though. It ends up under airlock fairly quickly, generally.

 

[joea132]

I don't add any K Meta at all and I've never had a problem. Enough CO2 comes off to protect the wine. I'm my opinion the little oxygen that does get in helps finish fermentation a little faster. My 2 high sugar wines in had to press at around 4 brix because it wasn't moving much more. The oxygen sped the fermentation along nicely.

 

[Turock]

We just press and don't take any steps to add meta. The grapes are only in the press for about 20 minutes and oxidation isn't an issue.

 

[winemaker_3352]

I don't add any k-meta either - just press the grapes. Once i get the juice out - then i will add k-meta to the juice..

 

[Bartman]

I would never add k-meta at the pressing stage because of the potential for halting the last part of fermentation. Arresting fermentation as the yeast are starting to peter out - about a week to ten days after pitching the yeast - would leave the wine slightly sweet and some potential for later spontaneous fermentation if the sulfite levels get too low.

Oxidation is something that happens slowly - exposure to the air doesn't instantly oxidize the wine, just like getting an iron nail wet doesn't immediately make it rusty. Dissolving a bunch of oxygen in the wine by splashing it around would be somewhere in between, however.

 

[JohnT]

Wild duck..

I would need to know more as far as the exact process/stage in which you are pressing your grapes. I am not sure if you are pressing actively fermenting must, recently curshed garapes, or whole clusters of grapes.

Not knowing your process, I can go so far to say that, no, in all three cases oxidation is not a real concern (unless the PH is completely out of whack).

 

[joea132]

Another point is that malolactic bacteria is sensitive to k Meta. Adding any could discourage mlf of prevent it completely. I add k meta after MLF is complete.

 

[docjavadude]

I also do not worry about oxidation at pressing -- outside of pressing in a vacuum or under a cloud of inert gas, exposure to oxygen is just part of the process. And a healthy part, I would suggest. Since I do malolactic fermentation on most of my wines, there is no sulfite addition at or after pressing. The wine comes out of the press into buckets which get poured into vessels (either carboys or 8 gallon fermentation buckets) for a brief little rest (24 - 48 hours), after which the wine is racked off the gross lees into clean carboys. Shortly thereafter I inoculate the wine with Malolactic bacteria. The wine doesn't receive any sulfite until MLF is complete.

This has been my process for several years and it has always worked well. I pay a whole lot of attention to making and keeping the fermentation healthy, and try to have a welcoming environment for the MLF to take place after pressing. It's after MLF that I begin to closely monitor SO2 levels and protect the wine very carefully from oxygen exposure. SO2 and tannins are our friends when it comes to protecting our wines for the long term.

Having said all of this, I have made wine for several years with a few friends who are VERY "old school" and don't pay attention to ANY of these details. They ferment, press, throw a few campden tablets in, put an airlock on, MAYBE rack once, and bottle when they're ready to drink the stuff. They swear by the wine they've made this way, that their fathers and grandfathers made this way...

I personally enjoy the craft of it all as well as some of the science, so enjoy being able to more carefully monitor and craft the wine.

 

[dave1117]

In red wines, Meta is counter productive to MLF which will help your wine.