You are watching: How long can mayo sit out on a sandwich
Of every the anxieties surrounding taking job-related to lunch—and there are plenty, indigenous what to lug said having lunch in, come making sure claimed lunch isn't stolen—perhaps no one is as nagging together the anxiety approximately mayonnaise.
In short, human being seem persuaded that, if left in ~ room temperature for even a short duration of time, the mayonnaise on your sandwich will sprout all sorts of bacterial growths—growths the will cause illness, jae won ruin, and also all species of other tragedies.
A seminal study 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 into mayonnaise and also dressings."
To placed it just as plainly, but in layman's terms, store-bought mayonnaise contains enough mountain (from vinegar or lemon juice) come not only kill food-borne pathogens, but additionally to avoid them native forming.
What this method is the the angst around an egg salad sandwich—that is, the are afraid of letting the sandwich sit the end for an hour or 2 at room temperature because the mayo could spoil—is actually backwards. If anything, the mayonnaise is preventing microbial growth. The eggs (and turkey, and also sliced ham) would be an ext dangerous there is no it.
Karen, the government's cartoon food safety professional (yes, you check out that correctly), concurs with the results of the study. Civilization often finger mayonnaise as the culprit for food-borne illness, yet according to Karen, "usually it's the meat, poultry, fish or egg in a sandwich retained out that the frozen refrigerator for an ext than two hrs that is the tool for bacteria to grow." (For a cartoon, Karen is really rather informed around these things.)
Some crucial notes: This is only true through commercially-made, store-bought mayonnaise. Homemade mayonnaise, which offers raw eggs, is a different matter altogether, and also should be preserved cold. And also because other components of a sandwich space susceptible to spoilage, your lunch should more than likely not sit the end at room temp—and certainly not in the sunlight (on, say, the beach)—for hours and also hours top top end.
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But when it concerns your commute, or leaving a sandwich on your desk for an hour or two, you can relax. Emphasis on other lunch anxieties instead, prefer who stole her dessert from the fridge.