How to Keep an Open Bottle of Wine Fresh, According to a Sommelier
1. Always re-cork your wine. If you know that you’re not going to finish that bottle, keep it closed. It can be easy to leave the cork off until you’re ready to put the bottle away, but according to Hoel, re-corking the bottle immediately after each glass is your first defense to keeping your wine fresh. "It limits the amount of oxygen that's in contact with your wine and helps keep its flavor fresh for longer," he explains. 2. Keep your wine upright. If possible, avoid storing your wine sideways. "An upright position helps minimize the surface area...
Source: travelandleisure.com