You know those civilization who are telling you not to fill a tuna sandwich for that hike? Well, they're the persons who can take a hike, since mayo might actually be keeping us safe.

You are watching: How long is mayonnaise safe at room temperature


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Of all the anxieties surrounding taking occupational to lunch—and there space plenty, native what to carry said lunch in, to making sure claimed lunch isn't stolen—perhaps nobody is together nagging as the anxiety around mayonnaise.


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In short, civilization seem persuaded that, if left at room temperature for also a short duration of time, the mayonnaise on your sandwich will sprout all sorts of bacterial growths—growths the will reason illness, financial ruin, and also all kinds of other tragedies.


A seminal research from 2000 took a look in ~ the fragility the mayonnaise and set the document straight: "Salmonella, E. Coli O157:H7, E. Coli, L. Monocytogenes, Staphylococcus aureus, and also Yersinia enterocolitica die when inoculated right into mayonnaise and dressings."


To put it simply as plainly, but in layman's terms, store-bought mayonnaise consists of enough acid (from vinegar or lemon juice) come not only kill food-borne pathogens, but also to stop them indigenous forming.

What this method is the the angst approximately an egg salad sandwich—that is, the are afraid of letting the sandwich sit the end for an hour or 2 at room temperature since the mayo might spoil—is in reality backwards. If anything, the mayonnaise is preventing microbial growth. The eggs (and turkey, and sliced ham) would be much more dangerous there is no it.

Karen, the government's cartoon food safety expert (yes, you read that correctly), concurs v the results of the study. World often finger mayonnaise as the culprit because that food-borne illness, yet according come Karen, "usually it's the meat, poultry, fish or egg in a sandwich preserved out the the frozen fridge for much more than two hrs that is the tool for bacteria come grow." (For a cartoon, Karen is really rather informed around these things.)

Some crucial notes: This is just true v commercially-made, store-bought mayonnaise. Homemade mayonnaise, which offers raw eggs, is a various matter altogether, and also should be maintained cold. And also because other components of a sandwich room susceptible to spoilage, her lunch should more than likely not sit the end at room temp—and absolutely not in the sun (on, say, the beach)—for hours and hours top top end.

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But when it pertains to your commute, or leave a sandwich on your workdesk for one hour or two, you deserve to relax. Focus on various other lunch anxieties instead, prefer who stole her dessert native the fridge.