I’m new to home winemaking. I made red and white wines this year and have them resting in 54 L carboys (with air-locks) after the initial fermentation is completed. The storage room does have a pretty high temperature (65degF), but it doesn’t fluctuate.
After a month, I decided to start drinking the red one. It tastes great now. So, every weekend I open the carboy and have 1.5 L of wine siphoned into a regular bottle.
I’m wondering if opening the carboy every week (as a result more air in the carboy) can quickly harm/destroy the rest of the wine or not? Unfortunately, I couldn’t find the proper answer anywhere. I hope you, as a Guru in home wine making, could possibly advise me on this matter.
Thanks in advance for your appropriate reply.
Sorry to say, but what you are doing is just not going to work.
Your concerns are well placed. Having more air, or an increasing head-space, in any type of carboy will eventually be a bad thing for wine. In the short term–a few days or so–you’re probably okay, but over time the air will have its way with the wine.
The first thing that happens when you drain the wine from the carboy is it increases the surface contact area between the air and the wine. When the carboy is full and the wine is up into the neck, you may only have 3 square inches of contact space. When the carboy isn’t full you could have over a square foot of contact area–144 square inches or more.
What this all means for the wine is oxygen now has the ability to saturate into the wine at a much faster rate than before. Eventually the wine will begin to show signs of oxidation. The wine’s color will start turning brown, and the flavor and aroma will start to take on carmel characteristics.
The second thing having a half-full carboy can do to the wine is spoil it. Mold, bacteria and other little nasties are floating around in the air. They are everywhere. An individual cell or spore is no threat, but if it is in some of the air that is brought into the head space, it will have a place to land with plenty of nutrients available with which to grow.
Understand, that oxidation and spoilage will not happen overnight. But day by day, week by week it will slowly progress.
Having said all of this, the solution is simple. Be sure you are using sulfites on the wine such as sodium metabisulfite, and either bottle your wine or keep your carboys full. Even bottling the wine in gallon glass carboys or gallon glass jugs would be a vast improvement over your current situation.
Happy Wine Making,
Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.