Book 9, Question 132
Why Should We Throw Out Jars with Bulging Lids?
We throw out jars with bulging lids because a bulge can mean microbes inside are making gas! That is a warning sign that the food may be unsafe. Never taste a suspicious jar or can, and tell a grown-up.
More fun facts
- Canning both destroys microorganisms and seals jars, so food keeps much longer than fresh.
- Home canners use glass jars, often called mason jars, with two piece metal lids.
- When a jar seals well, its lid curves slightly inward.
- A lid that bulges outward is a sign of a bad seal.
- A canning pot needs at least 4 inches of space above the jars.
Sources: Exploratorium, Exploratorium
Questions kids ask
What should I do with a bulging jar?
Do not open or taste it. Ask an adult to throw it away safely.