Is leaving a spoon in jar of mayonnaise bad?

* Contamination: The spoon can pick up bacteria from your hands or the air, which can then be introduced into the mayonnaise. This increases the risk of spoilage.

* Mayonnaise breakdown: The metal spoon can react with the acidic ingredients in mayonnaise, potentially altering the taste or texture.

* Rust: If the spoon is not stainless steel, it could rust, contaminating the mayonnaise.

* Hygiene: It's simply more hygienic to store the spoon separately and use a clean one each time.

It's best to store your mayonnaise in the refrigerator and use a clean spoon each time you need some. If you're concerned about bacteria, you could also try using a clean rubber spatula, which is less likely to react with the mayonnaise.