Why Is My Yogurt Bulging?

Another and less-apparent reason why yogurt containers can bulge is altitude. Yes, you read that right. If you live at a high altitude and the yogurt container was sealed at a low altitude, the altitude difference can cause the lid on it to bulge.

This usually happens due to poor storage conditions. For instance, the temperatures inside your fridge might not be cool enough, causing the dessert to spoil at a much faster rate. Once opened, yogurt will spoil rather quickly. If you fail to close the treat properly before putting it in the fridge, cross-contamination can happen.

Bulging flavored yogurt should be discarded, Klausner advises, “since you can’t really know what causes the swelling.” In June of 1989, the United Kingdom had its largest recorded outbreak of food-borne botulism when an outbreak associated with contaminated hazelnut yogurt affected 27 people.

More often than not, a puffed-up lid on your yogurt container is a sign of bacterial activity. It’s also a timely reminder that it’s about to go off sooner rather than later.