However, there is an important distinction.
Bubbles do not prove that pizza is safe.
They simply tell you something about what happened during heating.
Appearance alone cannot establish food safety
A pizza can look perfectly normal and still be unsafe if it has been improperly stored.
Likewise, a freshly prepared pizza with an unusual bubble pattern may be perfectly fine.
Food safety depends on factors such as ingredient quality, handling, cooking, storage, and time spent at unsafe temperatures.
For example, leftover pizza containing cheese and other perishable ingredients should not remain at room temperature indefinitely.
According to the United States Department of Agriculture, perishable foods generally should be refrigerated within two hours, or within one hour when the surrounding temperature exceeds 90°F (32°C).
Most properly refrigerated cooked leftovers should be consumed within three to four days.
Food Safety and Inspection Service+1These guidelines matter much more than whether the cheese has bubbles.
