What would cause bubbles in an unopened bottle of white wine?

Bubbles in an unopened bottle of white wine are usually a sign of fermentation. Here's why:

* Secondary Fermentation: White wines are often fermented twice. The first fermentation is the primary one, turning grape sugars into alcohol. The second fermentation, which occurs in the bottle, creates carbon dioxide gas, which forms bubbles. This is typical of sparkling wines like Champagne, Prosecco, and Cava.

* Bottle Bombing: In rare cases, a bottle of still white wine might have undergone a secondary fermentation due to a fault in the bottling process. This can create a lot of pressure inside the bottle, potentially causing it to explode ("bottle bomb").

However, there are also a few other possibilities, although they are less common:

* Contamination: Microorganisms can sometimes contaminate wine, leading to secondary fermentation.

* Defective Cork: A poorly sealed cork could allow air to enter the bottle, which can introduce bacteria that might trigger fermentation.

If you find bubbles in an unopened bottle of white wine, it's best to:

* Inspect the bottle carefully. Look for any signs of damage or leakage.

* Smell the wine. If it smells sour or off, do not drink it.

* Contact the retailer or winery. They may be able to provide more information or replace the bottle.

Important Note: If you are unsure about the cause of the bubbles, it's always best to err on the side of caution and avoid drinking the wine.