I posted this on BA some time ago. I don't think anybody ever put much thought into this, but I was hoping to help clear the air for future beer drinkers (only those that'll actually read this though, I guess). Prerequisite knowledge: CO2 in solution is a function of the partial pressure of CO2 above the solution - Henry's Law - not a function of the partial pressure of any other gas above it. Earth's atmosphere is only a tiny fraction of CO2 (0.039%) and therefore, the partial pressure of CO2 in air in the bottle is negligibly reduced when using a vacuum sealer. Therefore, it doesn't actually "pull" any CO2 out of suspension. It does, however, remove a good portion of oxygen out of the headspace, reducing the amount of oxidation that happens in the bottle. The real issue is this: The vacuum sealers are a one-way check valve. They allow a pressure to be reduced on one side of the apparatus (within the bottle). However, with carbonated beverages, once the CO2 starts coming out of suspension to fill the headspace, the pressure inside the bottle increases to a level slightly over atmospheric conditions, the check-valve allows that pressure to be purged through the valve, and out of the bottle. I made this dandy little pic using AutoCAD to explain (you'll probably have to open it in a new tab to read the small text below the bottles): A simple stopper keeps the pressure inside and does not allow the beer to become flat just like a vacuum stopper, but since there is no check valve, the simple stopper will keep the carbonation in suspension until there is enough pressure to blow the stopper out of the neck (which has happened to me a few times). The vacuum sealer will simply open and purge the excess pressure, and reduce the amount of CO2 in suspension in your beer. tl;dr: vacuum stoppers bad, simple wine stoppers good. In summation: 1. A vacuum sealer WILL NOT pull a noticeable amount of CO2 out of solution (by means of Henry's Law). 2. A vacuum sealer will still make your beer go flat due to the check-valve mechanical nature. ___________________________________ Another point of interest: Q: What is the pressure that the check-valve opens at? A: I don't know exactly, but it really isn't too much. I've played with one and have blown air through it (holding it up to my mouth) and it wasn't difficult to get it to open up. Human lungs can really only exert about 2 psi of pressure (this was an experiment we did a long time ago in college where we blew into a U-tube filled with water and measured the height difference). With the average beer containing 2-3 volumes of CO2 dissolved in solution, there could be a pressure of at least 1 atmosphere above atmospheric. At serving temperature (38F) I have to keep my kegs at about 12-17 psi to achieve 2.5-3 volumes of CO2 in solution, with 30 psi required to maintain 4.5 volumes for my sours. This is a substantially large amount of pressure exerted in bottles. This is why most sours and Belgian beers are bottled in thick champagne-style bottles that can withstand that amount of pressure. Therefore, the pressure in your average bottle of beer is much more than enough to open the check-valve on the vacu-vin.