Can Ketchup Go Bad?

Yes, ketchup can go bad, but its shelf life depends on whether it's opened and how it's stored.

Unopened: An unopened bottle of commercial ketchup can last for up to a year in the pantry. Some sources suggest it might even remain safe for up to two years. However, always check the expiration date printed on the bottle. [Source: Multiple sources including Reddit, North Jersey, and Real Simple articles.]
Opened and Refrigerated: Once opened, ketchup should be refrigerated and ideally consumed within six months to maintain the best quality and prevent spoilage. [Source: Real Simple and North Jersey articles.]
Opened and Unrefrigerated: If left unrefrigerated after opening, use the ketchup within one month for safety. [Source: Real Simple article.]

Signs of Spoilage

While ketchup has a long shelf life due to its acidity and preservatives, it's important to watch for signs of spoilage. These include:

Mold: Visible mold growth indicates the ketchup has gone bad and should be discarded. [Source: Quora]
Off-odors or flavors: If the ketchup smells or tastes unusual or sour, it's best to throw it away.
Changes in texture: Thickening or separation of the ketchup can be a sign of spoilage.

Proper storage is key to maximizing the shelf life of your ketchup:

Store unopened ketchup in a cool, dark, and dry place. Avoid direct sunlight and excessive heat.
Refrigerate opened ketchup immediately. This significantly extends its shelf life and prevents bacterial growth.

Keep in mind that while unopened ketchup may last longer than its expiration date, refrigeration after opening is crucial for safety and quality.