The debate over refrigerating butter has been a slippery subject for a long time. It has inspired academic studies, TV segments and plenty of fodder for social media commenters.
“My husband always puts my counter butter back in the refrigerator, and honestly I might divorce him over it,” Kristen M. posted on Twitter.
“What kind of Bohemian is leaving the butter out?” Jonathan B. declared, responding to another Twitter user’s poll that showed overwhelming support for keeping butter battened down in the icebox.
The cold, hard fact about butter is that you can leave it on the counter – to a point.
“Bacteria thrive around water and sugar. Butter has very little of either and an extremely high fat content – at least 80 percent – so it’s an unfriendly environment for bacterial growth,” says Jamie Kandora, clinical nutrition manager at Tidelands Health. “However, that doesn’t mean you can or should leave it at room temperature forever.”
As a dairy product, which typically must be kept refrigerated, it might seem like butter should not be allowed to remain at room temperature for any significant length of time. However, because of its composition and the pasteurization process, which kills bacteria, it’s generally OK to leave commercially prepared butter out for a couple days, according to the USDA.
It’s important to distinguish between salted and unsalted butter, however. Salted butter is more resilient to bacterial growth than its unsalted counterpart, which is why many experts agree unsalted butter is best kept refrigerated or only left on the counter for a short period of time to warm up before use.
Eventually, after a few days at room temperature, even salted butter can turn rancid, ruining its taste. If you are going to leave butter out, store it in an air-tight container, which can help preserve it longer and limit contamination with dust or other airborne particles. Also be careful to avoid cross-contamination with other, more perishable foods.
If you want to keep butter on the counter, Kandora says, it’s best to do so in small batches – just enough to use in a few days. Keep the rest in the fridge until you need it.