Chefs Mike Reid, Jeremy Pang, and Nima Safaei, along with registered nutritionist Lily Keeling, have settled the long-running debate over where to store mayonnaise after opening. All four experts agree: once opened, mayonnaise belongs in the fridge.
Expert consensus: fridge after opening
In an exclusive interview, Jeremy Pang stated: "Mayo - a definitely no go outside of the fridge! My kids call it 'egg sauce' and you wouldn't just leave 1/2 cracked raw eggs lying around in a cupboard."
Mike Reid, who launched his YouTube channel earlier this year, echoed that sentiment. "Mayo - the one everyone panics about for entirely the wrong reasons. Shop-bought and unopened? Cupboard, genuinely - it's sold off a shelf, not a chiller," he explained. "Once opened, fridge. Homemade, with raw yolks, is the only one to be strict about, fridge, and eat within a couple of days. And that classic 'the mayo turned at the picnic' line is a myth - it's far too acidic for bugs to enjoy."
He added: "Nine times out of ten it's the chicken cooking in the sun next to it that gets you, not the mayo."
Food safety and quality
Nima Safaei said mayonnaise "should always be refrigerated after opening, regardless of whether it's homemade or shop-bought." Because the condiment is egg-based, it's best to keep it "consistently cold for both quality and food safety."
Nima also warned against leaving mayonnaise out during a barbecue or family meal. "One mistake people make is leaving the jar out on the table throughout a barbecue or family meal," he noted. "If mayonnaise sits at room temperature for too long, particularly on a hot day, it's best to discard any leftovers rather than return them to the fridge."
He suggested: "I'd also recommend buying a smaller jar if you don't use it often – you'll finish it while it's still at its best instead of having it linger in the back of the fridge for months."
Nutritionist and brand guidance
Lily Keeling, registered nutritionist and Recipe Development Manager at Green Chef, stated: "Mayo is one I'd always keep in the fridge once it's been opened. When unopened, it's fine in a cupboard, but I always keep it in the fridge. It's made with mostly eggs and oil, and can lose its freshness if it's left out at room temperature for too long."
Hellmann's, the world's most recognisable mayonnaise brand, also recommends refrigerating after opening. Its storage guidance states: before opening, store unopened jars in a cool, dark place like a pantry or cupboard, away from direct sunlight and heat. Once opened, refrigerate immediately, ideally in the door to avoid freezing. Mayonnaise should not be left out for more than four hours, and clean utensils should always be used to prevent spoilage.
Heinz also confirmed: "Our mayonnaise is the same storage as the ketchup, once opened this has to be kept in the fridge. This is printed on both our ketchup and mayonnaise bottles."
