Is It OK to Leave Butter on the Kitchen Counter? 

By Miki Kawasaki, published on Thursday, February 5, 2015
A Chowhound finds out that two friends keep butter out on the kitchen counter, not in the refrigerator. So SIMIHOUND posed the question to fellow 'hounds: Is this a common practice? And how long does room-temp butter last before it goes rancid?
If there’s one thing I know to be true, it’s that butter makes everything better. It’s the sunshine on my morning toast, and the magic on my corn on the cob. But this simple perfection doesn’t come about from just any sort of schmear. It has to be soft, easy-to-spread butter, pliable from sitting out at room temperature. If you’re using hard, brittle butter from the fridge, you’re doing it wrong.
But is butter that’s been left out on the countertop safe to consume? Let’s look at the facts: Butter is mostly fat, created by agitating cream until all of its fat globules stick together, giving the boot to most of the water in it. Butter made in the United States is at least 80 percent fat, while European varieties contain upward of 82 percent. The remainder is a mixture of milk proteins, lactose, and residual water suspended in teeny-tiny droplets.
In order for contamination to occur, microbes need a moist environment in which to spread. The water content of butter is so sparsely dispersed, however, that all of those fat globules do a pretty good job of stopping microbial growth in its tracks. And unless you’ve got your hands on some raw cream butter, chances are the product you’re eating has been pasteurized, meaning it was initially heated to a temperature at which pathogenic bacteria cannot survive. Additionally, salted and cultured butters stand an even greater chance of resisting harmful organisms—salt has natural anti-microbial properties, while the healthful Lactococcus lactis bacterium that is used to culture dairy products creates an acidic environment in which many organisms find it hard to flourish.
Thus, from a safety standpoint, butter left at room temperature is unlikely to do any harm. But there is one other concern that can’t be ignored: rancidity. If you’ve ever had a whiff of butter that’s been left out in the open for too long, you’ll know it well.
“Off” flavors develop in butter when it’s exposed to oxygen, which does two things. First, it breaks down fat molecules, producing free fatty acids that have an unpleasant aroma and flavor. Then, it also attacks the sulfurous amino acids that are naturally present in dairy, prompting them to give off a distinctive, cabbage-y odor. Exposure to light and air accelerates these processes.
You can keep your butter from turning by minimizing both variables. A covered, opaque butter dish is a start (steer away from those clear plastic ones). But the best option is a French-style butter crock, which consists of an inverted cup that is submerged into a water-filled vessel, expelling all air. The less exposure your butter has to the elements, the longer it will last at any temperature.
So if you shelter and smother your butter like the precious darling that it is, you should be just fine leaving it on the kitchen counter. Well, not literally on the kitchen counter, but you get my drift.
Looking for more butter conversation? Check out the Chowhound thread "Storing butter outside of fridge."
Original story written by Sarah Perry (May 6, 2013); Header image of Honey Butter from CHOW; graphic and photo of French butter dish from The Kitchn
Miki Kawasaki is a New York City–based food writer and graduate of Boston University's program in Gastronomy. Few things excite her more than a well-crafted sandwich or expertly spiced curry. If you ever run into her at a dinner party, make sure to hit her up for a few pieces of oddball culinary trivia.
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