I knew that butter lasted for a while out of the fridge, but didn’t realise quite how long – to the point that many people advocate never refrigerating it in the first place:
“In 2015, Ms. Mertzel sent samples of four brands of butter to a lab for testing. The finding: No sign of spoilage after three weeks of storage at 68 to 77 degrees Fahrenheit [20 to 25 degrees celsius]. She commissioned a similar analysis this year and found no spoilage after 30 days.
“‘This is a quality issue, not a safety issue,’ said Gina Mode, a butter researcher at the University of Wisconsin’s Center for Dairy Research. Butter will eventually go rancid but that won’t make people sick, she said. Ms. Mode in an informal survey of her colleagues found that 24 of 31 keep butter out, a telling data point among experts.”