Does mayonnaise need refrigerating?
We all know that at picnics, we have to be especially careful of mayonnaise-based salads. The potato salad, macaroni salad, and coleslaw. That mayo will spoil in the hot sun! Keep it covered. Put it out at the last minute and throw it out once everyone is served. It's like a biological time bomb. The salad that could kill us all!
When, all of it. Every word of it. Is FALSE. You're more likely to get food poisoning from contaminated meat or veggies in those salads than the mayo.
First, what is in mayonnaise? Oil. Vinegar. Lemon juice. Raw eggs. Salt. Spices. As we can see, most of this stuff won't really spoil. Everything but the raw eggs. Ah! But, in commercial mayo, the eggs are first pasteurized so they are CLEAN. Then we have the vinegar and lemon juice. Mayo is actually pretty acidic.
From Hellman's website, they state it should be refrigerated as higher temperatures will affect flavor. No mention of spoilage. But, to really get the facts, we go to the Association for Dressings and Sauces. Yes, it exists. They state mayo gets a bad rap. Most likely because homemade mayo is made with regular raw eggs which makes them very perishable. But, as stated, commercial mayo uses pasteurized eggs. The issue is cross contamination of other ingredients. Mayo isn't strong enough to kill new bacteria introduced into the salad. So, that pasta salad without mayo will go bad if you have other bad ingredients.
Other testimonies from the web state many people never refrigerate their mayo. NEVER. And, as Hellman's says, they're only concerned about loss of flavor. So, similar to ketchup, you can keep mayo in the pantry as long as you use it enough so that the flavor doesn't go south. Who knows how long that is. But, you won't get sick.