This is a guest post from Husband-i-lis: Ever since I invested in Lot18 (sign up if you haven't by the way) we've been enjoying progressively better wine. I've rationalized this with the notion that since we don't as frequently go out to dinner, we can spend a little more on enjoyable wine at home. The one challenge is we often don't want an entire bottle with dinner, so the enjoyment of a great bottle is tinged with a little stress that you're wasting a few valuable glasses. So I've been experimenting with cost effective ways to save a bottle.
There are a lot of products out there... and I'm confident a good number of them are pure snake oil. There are nitrogen/CO2 or argon sprays that with a few spritzes are supposed to "blanket" the wine. Funny because 1) N2 is actually lighter than O2 and 2) I don't remember suffocating the last time I laid down close to the ground even though the atmosphere is 2% argon. There's also the venerable vacu-vin, but how much air does this really take out of the bottle? Well, that's what we're here to answer.
To test this, I have a wine bottle with one of the newer vacu-vin stoppers. I like these better since we can put the vacuumed bottle in door of the fridge and not worry that it will get opened by a wayward lateral strike by a carton of milk. I tested three ways of creating a vacuum: an older model vacu-vin pump (which is well used); a brand new vacu-vin (the kind that now clicks to tell you when you hit the target vaccum); and a Foodsaver vaccum sealer (model 2840) with the accessory suction tube connected to a 1" PVC tube to fit over the stopper. To test the level of vacuum, I would vacuum out the same wine empty bottle with each, then invert the bottle under water and remove the stopper, causing the vacuum to suck water into the bottle until pressure equalized. The empty wine bottle holds 26 oz (filled all the way up to the top of the neck.) So how much water did each method suck up:
Old vacu-vin (pumped aggressively for about 20 seconds): 19 oz (73% air removed)
Newer vacu-vin, pumped only until the very first click is heard: 12 oz (46% air removed)
Newer vacu-vin, pumped agressively for about 20 seconds: 20 oz (77% air removed)
Foodsaver with DIY attachment: 16 0z (61% air removed)
So what have we learned? It's not worth bothering with the foodsaver DIY project. The vacu-vin can give you just as good a vacuum (equivalent to about 23" Hg if I'm doing the math right). But if you want a strong vacuum, you should keep going after the first click.
But what if the click is there because too much vacuum can be detrimental to the wine? Winemakers use vacuums only slightly higher than this to degas wine of CO2 created in fermentation. Maybe there are dissolved gases we want to leave in there. But it's not very satisfying to have only removed half the oxygen. Maybe that will make the wine degrade half as fast, but that's not that great. Solution: displace the oxygen. Em-i-lis got a Sodastream for Christmas so have a ready supply of the same gas some of those wine-saver sprays use but in much larger, less-expensive quantities. So here' s the new method I'm testing. Try it out and post how it works for you.
Step 1: vacu-vin agressively to remove ~70% of the air. (We'll only leave it like this for a moment so there shouldn't be an extreme amount of degassing.
Step 2: Use the Sodastream to fill an empty bag with CO2. I use one of the bags our newspaper comes in cut in half.
Step 3: Invert the bag over the vacu-vin stopper and reach through the bag to release the valve, sucking the CO2 into the bottle
Step 4: Repump with vacu-vin, this time stopping at that first click so we don't have excess vacuum pressure for extended time.
The result: we should have removed about (1 - (1 - 50%) * (1 - 70%)) = 85% of the oxygen. And since the wine is under moderate negative pressure, the CO2 taking up most the rest of the bottle shouldn't readily diffuse into the wine (we're not trying to make Champagne here!). A more advanced method would get a tank of argon from a welding supply store but I concluded this would cost about $150 for the setup so the Sodastream seems fine to start.