Bottle of pasteurized cranberry juice fermenting naturally??

[xjbobbin82]

I have a bottle of Nature's Promise organic cranberry juice (half-full) sitting in my room (55-65 degrees F) which has no preservatives, and says that it is pasteurized on the label. However, the bottle is building up loads of pressure on a daily basis.. I release it every day because it looks like it may explode! Even looks to be some lees on the bottom of the bottle! It's been in my room for a few days now, I can see bubbles rising to the surface.

I was under the impression that pasteurizing will kill any wild yeast. Is it possible for this to happen?

 

[BigRob]

If it's half full, you let half a bottle of unsanitary air into the bottle.