Just wondering why we refrigerate mayo after it’s opened and not before, too. Isn’t there eggs and egg whites in the ingredients? I mean, I know there are preservatives and whatnot to keep it fresh, but why don’t those preservatives work after the jar is opened? TIA.
My guess is that it’s the same as other stuff that’s been canned (using the term to mean both canned in glass and canned in metal). Once it’s opened, then the outside air has done its thing to it; before it’s opened, it’s in a sterile (or as near as can be for canning) environment.
Mayonnaise doesn’t have to be refrigerated. It is a myth that has been debunked many times here. People keep mayo in the fridge because they like cold mayo and because there is a chance that eventually it will oxidize slightly or the breadcrumbs you leave behind in it will start to produce mold, but I’d guess you run approximately the same risk with peanut butter.
Cake is made with eggs and milk, but you don’t refrigerate that, do you?
But cake will mold more readily than mayonnaise. You just eat it faster.
The vinegar in mayo is a preservative, so leaving it unrefrigerated is OK, though the longer it stays out, the more risk of problems.
Yeah - but the eggs and milk are cooked/baked and thus have changed properties so that’s comparing apples and oranges. I don’t mind leaving cooked chicken out of the fridge for half a day though I wouldn’t cook raw chicken that had been out of the fridge for half a day.
Mayo is fine outside of the fridge, but like posters mentioned before people prefer mayo cold and mayo stays better longer if kept in the fridge.
I obviously–well, I thought it was obvious!–wasn’t claiming that anything with milk and/or eggs can be left out (not that mayo is made with milk), just that it clearly isn’t the case that everything made with perishable ingredients needs to be refrigerated. (Actually, I’ve read on the boards that eggs can be kept out of the fridge, too!)
Plus, it’s not like my fridge is cramped and space is at a premium. I never look in and think “Man, surely some of this stuff doesn’t HAVE to be in here.” 
Really? Can I come live with you?
That being said, the schmancy imported mayo does tend to be refrigerated before it’s opened.
Schmancy imported mayo? Dude, where do you shop? Is it better than Hellmann’s?
Err… I’m pretty sure that leaving cooked chicken out is worse than leaving raw chicken out. As long as you cook the chicken thoroughly any bacteria (and chicken has thing like Campylobacter as a commensal) should be eliminated. So leaving raw chicken out for 6 hours won’t do you any harm (provided you cook it properly, no chicken sushi!).
Leaving cooked chicken out just provides a nice moist, warm, sterile playground for whatever’s floating round your kitchen. It’s definately not a good idea. Cooked chicken goes in the fridge where the low temp will retard bacterial growth.
I’ve never actually bought it, because it’s really expensive and I like Hellmann’s well enough. But my local Whole Foods carries it, and I’ve also seen it in cheese shops.
Also, the eggs in mayo are pastuerized before they go into the emulsion.
That’s a physical and spiritual impossibility.
Or at least it is west of the Rockies, since “Best” is an absolute.
Pardon me… do you have any White Poupon?
Are those right next to the fanciest Dijon ketchups at the grocery store?
You’ve obviously never had homemade.
Neither have I. 
What about things made with mayo like potato salad or chip dips? Are these OK the morning after the party?
Hellmans != mayonnaise. I know it says it is on the jar, but it’s nothing like the real fresh stuff.
Real mayonnaise is yellow, quite runny, tastes of the oil used to make it, and only keeps for about a day. It’s more like a dressing than a sandwich spread. You make it, use it, throw the rest. It’s really easy to make, too - I do it a lot.