Mayonnaise aficionados have divided themselved into some of the fiercest factions on earth. , those who would raise hell for Hellman's, and those who quietly but devoutly prefer . It's also not uncommon for mayo fans to open a fresh jar, only to find an old one in the back of their fridge.
Sure, it looks okay, but how long is mayo actually good for after opening? Store-bought mayo that has been opened and consistently refrigerated is good for about 2-3 months. (On the other hand, will only stay good for about a week.) Before mayonnaise is opened, it's considered shelf-stable thanks to its acidic ingredients (like vinegar) and salt content.
Once it's been opened and exposed to both the air and utensils, however, it's considered contaminated and must be refrigerated from then on to slow the inevitable growth of bacteria (and preserve the flavor and texture). Also, an open jar of mayonnaise should never be left out for more than two hours. At the two-hour mark, its temperature will rise into bacterial growth territory.
Unfortunately, if you've left a jar out for longer than that, you should probably throw it away and buy a new one. These are the signs that your mayo has gone bad If you reach for an open jar of mayonnaise from the bowels of your fridge but can't quite make out the Best By date, here are some tips for discerning whether or not this condiment is still good. First, a sniff test.
If there's anything sour or foul about the way your mayo smells, it has likely gone bad..