We all have condiments and dressings sitting in the back of our refrigerators (and would rather not admit how long they’ve been there). Due to the fact that mayonnaise or balsamic vinaigrette usually don’t get used everyday, it’s easy to forget when you bought them at the store—and how long they’ve been inhabiting the top shelf. 

That’s why it’s important to brush up on the signs of expiration, especially when it comes to salad dressing, which tends to get overlooked in the kitchen. We turned to an expert to learn exactly when your salad dressing needs to be tossed—either in a bowl or in the garbage. 

It Fails the Sniff Test 

Like most foods, salad dressing tends to take on an off-putting odor when expired. “This is because there are yeasts that produce gas when salad dressing has spoiled, and create off-flavors or odors in the process,” says food scientist Dr. Bryan Quoc Le. Trust your gut—any forms of rancid, unpleasant, or just plain weird scents warrant throwing it away. 

You’ll especially notice a sour odor with dairy-based dressings like ranch, Caesar, or Italian. Some have even likened a funky salad dressing smell to wet cardboard.

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