Occasionally, when opening a bottle of still white wine and pouring it into a glass, you may see some tiny bubbles in the wine. And, if you use a bottle stopper and pump to extract the air in the bottle, you may see bubbles coming up through the wine. So, what exactly causes this phenomenon and should you be concerned?

The bubbles actually come from small amounts to carbon dioxide (CO2). This is the gas used to carbonate your favorite soft drinks and appears in beer and sparkling wine. It is a natural product of the wine fermentation process. Usually, all the CO2 escapes from the wine during processing, but it’s possible that very small amounts remain trapped in the wine prior to bottling. This is especially true of wines that quickly go from fermentation to the bottle (i.e., “young wines”).

Carbon dioxide is also a natural preservative for wine. So, winemakers may actually add a small amount of carbon dioxide to prevent a wine from oxidizing (i.e., absorbing oxygen).

Finally, it’s also possible that the wine has continued to ferment in the bottle, thus trapping the CO2 in the wine. This is unlikely, but if your wine also has some sediment and/or appears hazy, the bubbles would be due to this post-bottling mini-fermentation.

The bottom-line is that a few fine bubbles in a wine are totally harmless. Simply the act of pouring the wine into a glass should free-up these bubbles or, if you give the glass a swirl, the bubbles should quickly disappear. But, the bubbles don’t mean the wine has gone bad; it’s nothing that can harm you. Cheers!